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NSF Grant DMR 0520425High School Teachers Summer Internship

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2012Chemistry is Sweet: Exploring the Glass Transition with

Hard Candy

Stefanie Corcoran

Teacher of Chemistry/Core Science

Serra Catholic High School

Table of Contents

Abstract ......................................................................................................................................................... 1

Introduction .................................................................................................................................................. 2

Background ................................................................................................................................................... 2

Figure 23 ..................................................................................................................................................... 15

Teacher Information ................................................................................................................................... 18

Time Required ......................................................................................................................................... 18

Suggested Group size .............................................................................................................................. 18

Safety Information .................................................................................................................................. 18

Vocabulary .................................................................................................................................................. 19

Materials ..................................................................................................................................................... 20

Procedures .................................................................................................................................................. 21

Lesson Plans ................................................................................................................................................ 26

References .................................................................................................................................................. 27

Appendices .................................................................................................................................................. 29

Suggestions and Tips for Teachers .............................................................................................................. 33

Educational Standards used and/or met .................................................................................................... 34

AbstractThe sequence involved in making hard candy can be comparable to many topics involving

Material Science, especially with ceramics and glass production. The main purpose of this lesson is tostudy how different amounts of sucrose, using weight percent, illustrate the phase diagram of sugar and

water. Another transition the students will be able to evaluate is the glass transition temperature

while further analyzing the presence of crystals in each sample resulting in bad development. By making

a homemade Differential Thermal Analysis (DTA) and using cheap and accessible ingredients, this lesson

will be very adaptable to any science classroom.

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IntroductionMaterial Science is the study of fundamental, scientific, and engineering principles that govern

the structure, behavior, and application of materials [1]. Many chemistry topics cover materials but in a

very broad approach by organizing all matter into two categories, metals and nonmetals. The nonmetal

part of Chemistry is expansive and rarely taught to the specific level that Material Science teaches. Onearea in particular is commonly left out of Chemistry curriculums, other than talking about its

applications in the lab. This area is part of the Ceramics group called Glass. With glass being produced at

such high temperatures, 1700C, it is difficult to show students how glass is produced and its properties

[2].

An adaptable alternative to help show students these properties is by making their own glass

through the use of candy. Hard tack candy is made with simple and inexpensive ingredients such as

sugar, corn syrup, and water [3]. By adjusting the amounts of ingredients, by weight percent, the

students can observe comparable properties found in glass, specifically sodium silica glass.

In this experiment students will study Material Science by comparing hard candy to sodium silica

glass in numerous ways. First the physical properties of both glass and candy can be observed for their

similarities. Then the production of each will be discussed including the use of modifiers and transitionsthat can be tied into the phase diagram of sugar water. Next the structure and physical properties can

be studied by testing the hardness of the samples and finding the glass transition temperature using a

homemade DTA. While looking at the structure students will be able to compare and contrast the

different arrangements of solids including crystalline and amorphous. Lastly the students can tie these

properties together to discuss the application of glass and what makes it a very useful material in our

everyday lives.

Objective

In this lesson the students will be able to understand, analyze and evaluate the following

principles of glass science and technology:

1. Solutions are a type of homogeneous mixture including a solute and solvent. Colligative

properties, such as freezing point depression, are associated with solutions that increase boiling

points and decrease melting points.

2. Solubility rates increase with rising temperature making a homogeneous supersaturated

solution upon cooling.

3. When a homogeneous melt is cooled the resulting structure will develop into a single crystal,

polycrystalline solid or an amorphous solid where the crystal formation has been inhibited.

4. Phase diagrams are charts that can be used to show different phases of a substance at varying

temperatures and concentrations including boiling point, melting point and solubility limits.

5. How to avoid the production of crystals by inhibiting them through the use of modifiers and

limiting nucleation sites such as bubbles, impurities, and errors in pouring.

6. Improve the amorphous structure in glass by increasing the number of different sugars in the

melt including inverting sucrose itself.

7. Finding the glass transition temperature to ensure a desirable texture and hardness to candy byanalyzing and evaluating graphs made by students through manual data plotting.

BackgroundIn science the first thing we always learn is how to categorize matter. First we label matter into

phases; solid, liquid or gas with some people adding plasma to the list as a fourth phase. From there we

categorize matter into metals or nonmetals. Specializing metals will produce another set of

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categorization. The point is that all matter has its place in life. We label all matter based on its properties

and structure. There is one type of matter however that is sometimes labeled under its own category.

This type of matter is called frozen liquid or glass. There are some urban legends about glass arguing if

it really is a solid or a liquid. In most textbooks, solids are matter that has definite volume and definite

shape where the particles are packed together in relatively fixed positions which only vibrate aboutfixed points. A liquid has a definite volume but indefinite shape where the particles are close together

but are able to move past one another [4]. Glass however acts as both a solid and a liquid wanting to be

stable like a solid but locked into a liquid state. Some scientists state that glass is in a jammed state of

matter with atoms moving very slowly to achieve their stable solid form of a crystal [5]. When molten

glass is quickly cooled the atoms are organized in a random pattern known as vitreous silica or an

amorphous solid. This structure is different than a crystalline structure which has long-range order,

meaning atomic units repeat themselves to form a lattice where gaps are filled [6].

Figure 1: different structures of solids [7]

The reason why glass forms an amorphous structure depends on many factors. The most

common former of Glass is Silica, or quartz, which can be found in the sand. The structural bonding of

silica is shown above and below with a crystalline lattice. The molecular geometry of silica is in the form

of a tetrahedron, shown below, with silicon being shared with four oxygen atoms. Silicon has fourvalence electrons and oxygen has two valence electrons which leaves a total of 4 extra valence electrons

to share with neighboring tetrahedrons [8]. Since each vertex of oxygen atoms are shared with another

silicon atom the net chemical formula gives SiO2 [9].

Figure 2: Tetrahedron structure of (A) ordered crystalline silica and (B) amorphous SiO2[10]

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Molten silica however has a non-crystalline structure, mainly because molten silica is extremely

viscous. One reason why it is so viscous is because of the different types of bonding present. Silicon

dioxide is a network solid which has mainly covalent bonds with some ionic characteristics causing it to

form random networks [7]. Viscosity and mixed bonding are only a couple reasons why crystallization is

inhibited in glass. Other reasons are hydrogen-bonding, cooling rate, colligative properties, and thepresence of different materials in the glass. As stated before, viscosity causes an amorphous solid

because as the glass cools the viscosity increases to a point where the atoms can no longer move, but

are locked into a disorganized and random pattern. Because of this, the solid has many vacancies or

gaps which can be seen in the above figures. However, viscosity alone could still form a crystal. The

cooling rate is another factor that can inhibit crystallization. If silica is cooled slowly, a crystal can still

form since the atoms have more time to become ordered. If silica is cooled quickly, the atoms do not

have enough time to get into their original structure causing vitrification [10]. Think of it as musical

chairs. If kids are given a longer time period, they will make it to their original ordered seats. If the

music is stopped quickly the kids have to sit down where they are in a more random network. The last

way to inhibit crystallization is by adding a colligative factor to the glass to help block the SiO2 bonds

and lower the freezing temperature at the same time [7]. In glass science this colligative factor is called

a modifier. In the production of soda-lime glass both sodium oxide (soda, Na2O) and calcium oxides

(lime, Ca2O) are mixed with silica to make it more durable, decrease melting temperature, and make it

more moldable. As shown below the soda will act as a bridge between the silicon-oxygen bonding,

making Si O-Na+or Si O-Ca2+bonds, hindering crystallization forming networks instead [10]. The

soda, a modifier, will also cause a freezing point depression from 1723 C to 850 C. Sometimes cullet,

or chunks of the same type of glass, are added to the mix to decrease the melting temperature. The

lime, called a stabilizer, is merely added to the soda-lime glass to make the glass water-insoluble for

application purposes since soda is water-soluble [7].

Figure 3: Sodium Bridge and soda-lime glass structure [7]

Since silica can be either crystalline or amorphous, the point at which a glass or crystal is formed

is important. The point at which molten silica will vitrify is known as the glass transition temperature, or

Tg, while the point at which it will crystallize is called the crystallization temperature. The temperature

near the Tgis most important when trying to produce a glass since this is when crystallization will occur

due to nucleation. The crystallization temperature is very uniform since each structured bond in the

silica will break the same way. On the other hand, the glass transition temperature of silica is not very

precise, ranging between 100 C - 200C. This is because the networks are bonded differently causing

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different energies to break those bonds [7]. A phase diagram for glass is shown below including both

the crystallization and glass transition temperature, dependent on whether a crystal or glass is formed.

It should be noted that there is no phase change, or melting point, from glasss solid state to the liquid

state like you see with crystals. Instead, glass softens regularly when heated.

Figure 4: Silica phase diagram [7]

The properties of glass are in direct correlation to the structure. The first property which is

related to the phase diagram of silica is the fact that glass softens as it is heated rather than having

sharp melting points. Because of this, glass can be heated until soft where it can be moldable similar to

metals. Glass can be casted, blown, cut, rolled, and drawn into various shapes and sizes based on its

application.

The hardness of glass depends on thermal history and surface flaws. Glass is considered brittle

to an extent since there are no grain boundaries in an amorphous solid. Grain boundaries are found in

crystalline structures where the atoms cant slide past one another to relieve stresses. Since amorphous

solids do not have these grain boundaries to release stress a crack is made on the surface where a

surface flaw is located. Once a crack forms the overall stress is located at the tip of the crack making it

grow until it eventually breaks. This is why you should always score glass before trying to cleanly break

it [10].

To increase glass hardness, glassmakers use a process called annealing and tempering.

Annealing glass in an oven called a lehr will harden the glass by eliminating any imperfections like

bubbles or defects. During this process the glass is heated until softened then cooled slowly. If glass is

not annealed it will break easily due to stresses when cooled too quickly [11]. Tempering glass is another

way to strengthen glass by heating it to the softening point, past the annealing temperature, and cooling

it quickly. This will result in glass that is up to seven times stronger than non-heat treated glass. Becauseof the annealing and tempering methods in glass making, glass has a great property of being shock

resistant. This is why chemists and other scientists use Pyrex beakers when quickly transporting beakers

from a hot to cold environment. However this property is only available in certain glasses where the

application is needed, like in science labs rather than in household drinking glasses.

Another property that makes glass stand out from other materials is its transparency. Crystals are what

we call anisotropic because it has many grains that can fracture in a number of directions. Wood is

another type of anisotropic material since you can visibly see the different grains going in different

Freezing point

Melting point

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directions. Glass, however, is called an isotropic because it does not have grains resulting in properties

being the same in all directions. Therefore when light hits a crystal its scattered making the crystal look

translucent or opaque while glass will look transparent since light will move through the medium in the

same direction [11]. This is also why glass is used as fiber optics. Light and information can be

transmitted through very thin strands of glass without being scattered. Because of glass being used inthis application it must also resist electrical current. This means that glass stores electricity very well

being used to transport and insulate it. [12]

Another reason why glass is transparent is the same reason why glass is a good insulator of heat

and electricity. The reason has to do with the atomic structure of glass. Electrons travel around the

nucleus of an atom in set places called orbitals, or energy levels. Each electron lives in a specific spot

inside these energy levels with a specific energy, momentum, and spin with no two electrons having

these same values. The energy of these electrons can change by moving up or down between the

energy levels. There are gaps between these levels where electrons do not travel because energy does

not exist called bandgaps [13]. The energy levels closest to the nucleus are called core, or ground

levels, while the outermost level is called the valence level where the electrons are localized. Then there

is a band called the conduction band which lies past the valence shell where electrons can roam freely,

or are delocalized. In some materials like metals, which are good conductors, the valence shell and the

conduction band overlap causing electrons to move freely causing it to be a good conductor. Glass, on

the other hand has a large space between the valence shell and the conduction band which makes it

difficult for electrons to move up to that level causing electricity to get blocked and not flow easily [13].

The same principle lies for glass being transparent. All materials have energy including energy levels

since they are all made out of atoms. However different materials will have bigger or smaller bandgaps

depending on their structure. The bigger the bandgaps the higher the energy needed to move electrons

from one energy level to another. Glass has a bigger void between their energy levels needing energy

with a smaller wavelength to move electrons. Therefore, visible light with a wavelength of 400-700 nm

are not energized enough so the light will pass through glass instead of being absorbed or reflected.

Ultraviolet light, however, has a smaller wavelength of 10-400 nm causing the light to be blocked

instead of passing through. This is why you cant get sunburn from light passing through your windows.This application of glass makes it very useful in greenhouses and sunglasses where ultraviolet light can

be damaging.

Glass is also elastic, meaning it is flexible and will return to its original state after being bent. The

point at which glass can be bent to a point of breaking is around 69-72.5 Giga Pascals (GPa2) which has

an elasticity comparable to aluminum [14].

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Figure 5: Table of Elastic Modulus and Poisson ratio for common materials [14]

The last property that makes glass a very versatile material is the fact that it is chemicallyresistant with most chemicals and it does not corrode easily. One solvent that does readily attack glass

is hydrofluoric acid which is sometimes used to etch glass [15]. This important property of glass is why

many chemists store their chemicals in glass bottles rather than plastic or metal. Plastics will dissolve in

most chemicals while metal will corrode.

Even though glass has many important aspects to learn including their properties, production,

and application, it is difficult to teach in an ordinary classroom setting. This is because the production of

glass is hard to replicate due to supplies and safety concerns, especially when dealing with expensive

and scorching furnaces. In order to educate students about the versatile material that glass has become

in our everyday lives we must use a comparable type of glass called edible glass, or hard candy.

Sucrose, or table sugar, is an organic carbohydrate with a chemical formula of C12H22O11. Sucrose is also

a crystal with a very ordered arrangement of sucrose molecules [16]. Sugar is what we call adisaccharide because it is composed of two simpler sugars called monosaccharides. These

monosaccharides, shown below, are called fructose and glucose which are bonded together in sugar.

Figure 6: 5 ringed fructose molecule [17] Figure 7: 6 ringed glucose molecule [17]

Both of these monoscaccharides are called conformations because they have the chemical formula of

C6H12O6, but they are look different [17]. Fructose has a five-membered ring, while glucose has a six-

membered ring. These are easily remembered by the letter f for fructose and five. When any of these

sugars are put into a solution they may form rings or open up to form chains constantly switching from

one form to the other. Some may even collide forming a larger molecule by bonding [17].

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Figure 8: Glucose closed and open [17]

Sucrose is created when the glucose and the fructose molecules combine in what is called a

condensation reaction because one of the products created is water. Pictured below you can see the

oxygen, bonded to the hydrogen, on the glucose molecule bonds to the left-most carbon of the fructose

ring. This leaves the oxygen and hydrogen, attached to the fructose molecule, to bond with the leftover

hydrogen atom from glucose to form a water molecule [17].

+

Figure 9: condensation reaction of glucose and fructose to produce sucrose and water [17]

Sucrose, when mixed with different ingredients such as water and corn syrup, can be heated

past boiling to a point where glass can be achieved. This glass is very comparable to commercial soda-

lime glass that is found in drinking bottles. As mentioned before, glass has very specific properties that

make it the material it is. For hard candy to be comparable to glass it must also have the majority of

these same properties including being amorphous, transparent, moldable when softened, and hard.

Just like in the production of glass, hard candy has certain ingredients to make it amorphous.

The glass former in this recipe is sucrose while the modifier is corn syrup. Water can be thought of

as the stabilizer since it will keep the sugars from burning.The first step in order to make sucrose

amorphous is to dissolve it in water. By looking at the binary phase diagrams of sugar water below the

ratio of sucrose to water can be calculated to give a saturated solution. Upon heating, the saturated

solution will become a supersaturated solution since water will be driven off.

New bond

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Figure 6: phase diagram of sucrose and water

not in equilibrium due to viscocity [18]Figure 7: Phase diagram of sugar and water including

solubility curve and clearing point [7]

Figure 8: phase diagram of sucrose and water with boiling point included [19]

Since sugar itself is a crystal it is difficult to produce a glass with sucrose and water alone,

especially with high sucrose content solutions. Since supersaturated solutions involve a higher amountof sugar in solution than normal it is very unstable. The slightest bit of agitation including stirring or

bumping the solution will cause the solution to crystallize back into its ordered structure [16]. When the

solution is agitated nucleation may start where one of the sucrose crystals can become a nucleation site

causing more crystals to form. In the end, the entire solution will be full of tiny crystals growing off of

each other like in the figures below.

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Figure 11: (a) Nucleation of crystals (b)crystal growth (c) crystals growing together (d)grain boundaries as seen in amicroscope [8]

For solutions that are higher in sugar content the ease of crystallization decreases slightly since the

solution becomes more viscous. The higher the viscosity of the solution the slower the molecules will

move meaning less interaction between the sucrose molecules to form crystals. This results in the

solution having a region of stability called the metastable region. This region is below the solubility curve

where crystal growth is sluggish especially in a 2:1 ratio, or 66% sucrose to 33% water for weight

percent. When solutions are in a 3:1 ratio, 75% sucrose to 25% water, crystallization may become

spontaneous [19]. Pictures are shown below comparing the crystal presence in 60% sucrose versus 80%

sucrose, along with another phase diagram to show where this metastable region is located.

Figure 12: phase diagram of crystallization of sugar [8] Figure 13: Spontaneous crystallization of 80% sucrose with20% water shown left and 60% sucrose with 40% water on

right

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Another way to increase viscosity, and inhibit crystal, growth is the addition of different types of

sugars to the candy solution. This can be done by either inverting the sucrose to form different sugars

or by simply adding different sugars. By inverting sucrose the disaccharide is broken down to form the

original monosaccharides of glucose and fructose. This is done by adding an acid like citric acid, lemon

juice, or cream of tartar to the sugar by hydrolysis to form fructose and glucose. When the reaction iscatalyzed by hydrogen ions from the acid, a water molecule is added to the sucrose molecule breaking it

down as shown in the figure below [8]. By addition of different sugars to the solution the different sizes

and shapes of the molecules will act as a wall, or barrier, by blocking the sucrose crystals from growing

together.

Figure 14: inversion of Sucrose [8]

The addition of corn syrup to the sucrose mixture is another way of simply adding sugar to the

candy solution. Corn syrup is a type of glucose syrup that will work well to inhibit this crystal growth and

it will even add more viscosity to the solution extending the metastabe region [19]. Corn syrup contains

glucose polymers which are long chains that get entangled between the larger sucrose molecules

preventing them from interacting. Corn syrup also acts as a modifier since it will lower the boiling point

of the solution due to its lower melting point. Other possible sugars that could be added to the sucrose

solution to help extend the metastable region are found below with accompanying melting

temperatures.

Figure15: Melting points for some mono-, di-, and trisaccharides [8]

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After the candy solution is prepared, the mixture is heated where the viscosity will continue to

increase. Upon cooling this viscosity will again increase until it becomes so viscous it turns into a solid,

or glass, keeping it safe from spontaneous crystallization [19].

When testing candy for doneness, the ball test is used where a small amount of molten candy is

quenched in a bowl of cold water. Quenching the candy will cool it quickly where the molecules arelocked into place forming an amorphous solid. Depending on the weight percent of sucrose and the

temperature of the candy, different physical characteristics are observed as shown in the table below.

Figure 16: different temperatures of sucrose for food purposes [17]

Hard tack candy is boiled to a temperature of 145-150 C where the candy will pop when

quenched, forming a hard ball that is crunchy when chewed. The temperature will rise abruptly when

this temperature has been reached since there is little to no water left in the solution. The solution will

start to turn yellow to brown indicating the sugar being broken down into fructose and glucose [19].

The temperature where candy is at its optimal hardness is called the glass transition temperature, T g,where the candy goes from a rubbery state to a glassy state. The rubbery state would be below the Tg

having the consistency of taffy while the glassy state is at or above the Tghaving a hard consistency like

toffee or hard candy. A good indication that the candy is reaching that hardness level is when fibers are

able to be drawn, similar to the fiber optics produced from glass. The glass transition temperature can

be seen on a heating curve of a solution being present as a slight step before the melting point as shown

in the graph below. The glass transition is not a phase change but merely a transition of the amorphous

region of a semi-crystalline solid [20]. This transition is a second-order transition where the heat

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capacity changes with no transfer of heat between the system and the surroundings like one would see

in a first-order transition, such as the melting temperature [20]. The T gof a good hard candy should be

between 40-50 C.

Figure 17: phase diagram including Tg[7] Figure 18: phase change versus glass transition temperature [20]

When finding the glass transition temperature a commercial machine called a DSC, or

differential scanning calorimeter may be used. More than likely, this machine is not conveniently

available so another machine called a DTA, differential thermal analysis, can be used to measure the

heat capacity of a substance going from a glassy state to a rubbery state, or vise-versa. The heat capacity

is measured by calculating the change in temperature of a reference compared to a sample when placed

in the same environment. A simple DTA can be constructed using test tubes, one filled with the

reference material and the other filled with the sample material, placed in a beaker of oil representing

the environment [21].

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Figure 19: DTA set up [21]

Figure 20: Thermocouple placement [21]

Figure 21: Circuit prepared

by Dr. Heffner from

Lehigh University [21]

A T-type thermocouple made out of soldered copper and constantan wire will be used to

measure the differential temperature of the test tubes, while a digital thermometer will be used to

measure the temperature of the oil bath. The thermocouple was chosen since it measures differential

temperature more accurately without environmental error, is sensitive enough to be used in our

experiment, and can withstand higher temperatures [21]. The test tubes will be placed in the oil bath

held by a pre-drilled piece of wood that can be placed over the beaker when heated on the hot plate.

Once the set-up is properly assembled, the soldered end of the thermocouple can be placed correctly

inside the test tubes and then connected to the amplifier circuit as shown in the picture above. The

amplifier will increase sensitivity to the multimeter producing better data points. The thermocouples

should be placed in the test tubes to a level at least midway from the bottom of the test tube to the

surface of the vegetable oil. The reference and sample material should also be at an even line with the

vegetable oil. When connecting the copper ends of the thermocouple to the multimeter the sample lead

should be plugged into the positive while the reference should be plugged into the negative. This will

result in a graph that has an endothermic peak when energy is absorbed and an exothermic dip whenenergy is expelled. By flipping the positive and negative terminals you will have the opposite effect

depending how you want your graph to look [Heffner]. Recording data every thirty seconds of the bath

temperature, delta T of the test tubes, and observations should give sufficient data to find the Tg of the

sample material. The data should be graphed against eachother with bath temperature being on the x-axis while Delta T is on the y-axis. Taking the midpoint of the Tg step will calculate the glass transition

temperature effectively as shown in the graph below.

Copper leads connected

to circuit

Multimeter leads

connected to circuit

9 Volt batteriesMeasured in volts

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Figure 22: DTA graph of 60% sucrose, 30% corn syrup and 10% water mixture [21]

A calibration curve should be run to make sure the amplifier circuit, multimeter, and

thermocouple are reading successfully before testing the candy solutions. Stearic acid is used to

calibrate the DTA sufficiently since it has a very sharp melting point around 70C. Stearic acid should be

placed in the sample tube slightly higher than the oil level since the volume will shrink upon melting.

Melting the stearic acid with a hairdryer prior to calibrating will help obtain the correct amount of acid

to be become level with the oil in the bath [21]. However, the acid must equilibrate to room

temperature before starting the calibration. By again taking measurements of the bath temperature

against the differential temperature of the test tubes a graph should be made to illustrate the melting

point as shown below.

Figure 23 Stearic Acid calibration showing an endothermic peak at 72 C

Midpoint: Tg = 43C

-200

0

200

400

600

800

1000

1200

1400

0 20 40 60 80 100 120 140

BathTemp (C)

DeltaT(mV)

Series1

Tm=72C

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If the melting point is near 70C the DTA has been successfully calibrated. The graph below was

set up with a different convention showing an endothermic peak rather than a dip due to the sample

being connected to the negative end of the circuit showing Treference - T sample.

After the calibration curve has been successful, quenched candy samples may be tested using

the same steps as previously stated. The candy must be quenched first then patted dry to get as muchmoisture out of the candy as possible before testing. A graph is shown below for 60% sucrose and 40%

water with a Tg of about 50 C. Due to a slight noise error with the thermocouple however, the Tg is

most likely around 48C. The Tg for optimal hard candy should be in the 40-50 C range. Another

sample of 60% sucrose and 40% water along with a sample of 60% sucrose, 30% corn syrup, and 10%

water was tested using a commercial DTA at Carnegie Mellon University. This graph is also shown below.

However there is an error here with the sucrose and water sample due to humidity factors of the candy.

The candy was transported during a hot day to a local University, Carnegie Mellon. The humidity caused

a lower Tg which proves another benefit to creating your own DTA apparatus at home. The other

benefits are energy conservations, cost, and the ability to observe the candy as it is being heated.

Figure 24: DTA graph of 60% sucrose, 40% water from homemade DTA.

60% sucrose 40% water

-700

-600

-500

-400

-300

-200

-100

0

100

0 20 40 60 80 100 120 140

Bath Temp (C)

DeltaT(V)

Series1

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Figure 25: DTA analysis from CMU for 60% sucrose and 40 % water

Figure 26: DTA analysis from CMU for 60% sucrose, 10% water, 30% corn syrup

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Teacher Information

Time Required

1-2 45 minute lecture period to teach students about ceramics and glass materials.

1

45 minute lab period for glass station experiments.2 45 minute lab periods for candy making, DTA analysis and lab discussion.

Suggested Group size

Group size for this lesson will fluctuate depending what labs are being performed. For glass stations

there should be groups of two where both students will be involved in the lab. For the candy making and

DTA labs I suggest groups of four. I also suggest matching up two pairs of partners that worked together

during the glass stations lab so they can discuss and compare the difference between the glass they

observed and the candy they will make.

Safety Information

There are different safety concerns for each of the labs preformed. For both days of lab goggles MUST

be worn along with closed toed shoes, possibly an apron depending on students, and hair tied back if itslonger than chin length. For the glass stations lab the following safety concerns should be followed for

each station:

All filed ends of glass tubing should be fire polished and allowed to cool completely before any

station, including letting each end cool before fire polishing the next. These ends may be sharp

and could potentially cut a student.

Hot glassware looks the same as cold glassware. Students must test the temperature of their

glass tubing by feeling for heat with the back of their hand. DO NOT let students cool down

their glass tubing by running it under cold water. This will shatter the glass.

When blowing a glass bubble make sure there are no students standing across from each other

since the bubble could shatter.

Students will need room to pull fibers during the optical fiber station so make sure they are atarms length away from each other.

For the candy making lab the following safety concerns should be followed for each station:

Pyrex beakers MUST be used to handle the temperature changes of the experiment or

beakers could shatter. Check for cracks and stars for all glassware before starting.

Students should be aware of their surroundings when pouring molds so they are not pouring

candy over each other. Hot candy may form fibers that could burn others.

Candy may be sharp on ends when cooled after quenching, or for certain molds. Students

should be careful of this when breaking off samples from quenched candy and when eating

candy shards.

When cooking candy, or finding the Tgusing the DTA, a cookie sheet should be placed underthe hot plate to catch any spills from the experiment.

When using the DTA, students should be mindful of hot oil and potentially harmful burns.

When calibrating the DTA with stearic acid please be aware that stearic acid is combustible

and should be placed away from any oxidizing agents.

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VocabularyAmorphous- Relating to a substance whose molecules have no definite regularity or order

Annealing: Process by which a hot glass item is (after completion) uniformly re-heated and then

gradually cooled down over many hours in the Lehr, in order to toughen it and make it less

likely to crack when subjected to changes of temperatureCasting: Ladling hot glass into a mould and allowing it to solidify before annealing

Condensation reaction: a chemical reaction where two molecules combine to form one

molecule with the loss of a water molecule

Colligative property: property of a solution that can fluctuate depending on the ratio of solute

particles to solvent particles.

Conformations: type of structural isomer where molecules have the same chemical formula but

have different structures due to different rotations.

Crystalline: a type of solid that is characterized by an orderly arrangement of atomic particles

called a lattice.

Exothermic :type of process that releases energy into the environment usually creating heat

Endothermic: type of process that absorbs energy from the environment in the form of heatFreezing Point Depression: type of colligative property produced when adding a solute to a

solvent that results in the freezing point of the solution to lower.

Glass: An inorganic material that, when allowed to cool from a melted condition, becomes rigid

without becoming crystallized.

Glass Former: This is the main component of glass, which has to be heated to a very high

temperature to become viscous. Silicon dioxide (contained in sand) is the most common

former. [12]

Glass Modifier (or Flux): Helps formers melt at lower temperatures. This is usually soda ash

or potash. [12]Glass stabilizer: Keeps the finished glass from dissolving, crumbling, or forming unwanted

crystals. Calcium oxide is a common stabilizer. [12]

Glass Transition Temperature: transition in an amorphous solid resulting in a change from the

molten rubbery state to the hard brittle state

Heat capacity: measure of the amount of heat needed to change a substances temperature by

a given amount

Inverting: process of breaking down a disaccharide, such as sucrose, into its constituent

monosaccharides fructose and glucose.

Network solid: each atom is joined to all its neighbors in a covalently bonded, three-

dimensional network

Nucleation: The initial process of when crystals start to form in a solution

Nucleation site: The site at which nucleation begins and where crystals start to grow

Transparent: the property that allows transmission of light through a material making the

material look clearVacancy: A gap in an atomic structure where an atom should be placed.

Vitrification: transition into glass (vitreous: glass-like)

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MaterialsGlass stations lab:

Glass tubing (5-6 mm)

Propane torch, Bunsen burner with wing top, or Fischer burner (hot flame needed)

Candy making lab:

Pyrex Beakers: 400 mL

1 bag Sugar for each class (regular sucrose found at grocery stores)

2-3 bottles Light Corn Syrup for each class (Karo or generic is fine)

Distilled water

*Citric acid crystals (3 grams for one batch)

*Silicone molds, ice cube trays and/or lollipop molds (silicone is easy to pop out candy)

Cookie sheet (used under hot plate to catch spilled candy or oil)

Beaker (200 mL or bigger for hot water to clean candy off testing spoon)

Spoon for testing (plastic will be better so students wont get jumps in the data from metal)

Shallow Bowl of cold water for testing candy (beaker may be too deep)Microscope to view crystals in candy

Oven mitts ( to remove beaker from hot plate to pour molds)

DTA apparatus

Hot plate with stir bar

Vegetable oil

Wooden kabob sticks (to test softness of sample material when being heated)

Thermocouple: Constantan wire and telephone wire (copper wire) soldered together with

soldering device (long enough to run wires from multimeter to test tubes)

*Multimeter with thermocouple and lead attachements

*Piece of 1x4 piece of wood (white pine) for DTA set up with predrilled holes (picture attached)*Test tubes with rim (16 x 150mm for 1500 mL beaker) (13 x 100 mm if using 250 mL beaker)

*Digital thermometer (needs to withstand up to 200C)

Pyrex Beaker: 1500 mL (this is what I used but a 250 mL beaker will work as well)

Figure 27: Materials needed for experiments and where to find them including prices.

Digital thermometer Taylor 9842 Waterproof Digital Thermometer on Amazon $11.43

Multimeter 11 Function Digital Multimeter on Amazon for $39.99

Constantan Wire Model number: TFCI-010 diameter: 0.25mm or 0.010 inch from Omega $16

Test Tubes 16 X 150mm Pyrex glass test tube with rim; 6 pack from Amazon $11.40

Silicon molds Freshware 24 Cavity Silicone Financier Pan (pour flat for slides) Amazon $12.99

Lollipop Molds Mini Smiley Sucker Hard Candy Mold HS-9824 from Amazon $3.45

Citric Acid Crystals Food Grade Citric Acid From Bulk Apothecary for $4.95 (1 lb)

Dimensional Lumber 1 in. x 4 in. x 8 ft. Spruce-Pine-Fir Furring Strip $1.99 from Home Depot or Lowes

Amplifier Circuit Made by Dr. Heffner from Lehigh University but a prewired AD595 can be

purchased athttp://www.simplecircuitboards.com/Thermocouples.html
http://www.simplecircuitboards.com/Thermocouples.htmlhttp://www.simplecircuitboards.com/Thermocouples.htmlhttp://www.simplecircuitboards.com/Thermocouples.htmlhttp://www.simplecircuitboards.com/Thermocouples.html

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ProceduresGlass Stations Lab: Day 3 of lesson

**make sure each station is cleaned up before moving to the next**

Station 1: Bending Glass [10]1. Use a triangular file to cut a piece of 5 mm tubing about 15 cm long.

2. Fire polish each end. Be sure to allow the first fired polished end tocool before attempting to fire polish the other end.

3. Grasp both ends of tubing. Hold the middle part of the tubing in thehottest part of the burner flame. Rotate the tubing to evenly heat all sides.

4. When the heated portion gets soft and wobbly, remove glass from heat.Smoothly bend the ends of the glass tubing upward to form a90 degree bend.

Station 2: Making an Optical Fiber [10] Figure 28: Bending Glass [10]

1. Cut a piece of glass rod about 20 cm long.2. Use a flame spreader on the Bunsen burner. If using a propane torch, move the rod back and forth in

the flame to soften at least 4 cm of the glass.

3. Use both hands to heat the center portion of the rod. Rotate while heating.

4. When rod is fairly soft and wobbly, quickly remove the rod from the burner.

5. Rotate rod so that it is vertical. Quickly spread your arms while firmly grasping the rod.

6. Allow the fiber to cool. Measure and record the length of the thin part of the rod.

7. Check your fiber to see if it will transmit light with laser pointer

Station 3: Blowing a Glass Bubble [10]1. Cut a piece of 6 mm tubing about 30 cm long.

2. Fire polish one end of the tubing and allow to cool.

3. Heat the end that has not been fire polished until it is soft. Then use a pair of pliers to seal the end orpush it against a ceramic tile. It is also possible to allow the end to close on its own with enoughheating.

4. Heat the tubing about one cm above the sealed end until it is soft. Quickly remove the tubing fromthe heat and blow into the cool end while rotating the tube. Some people prefer to leave the glassin the flame while blowing.

5. Repeat step 4 until you have a bubble with a diameter about twice that of the tubing. As the glass

walls of the bubble get thinner use less air pressure to avoid bursting the bubble.

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Candy Making Lab: Day 4 of lesson

1. Partners will be responsible for making two samples the whole class will be observing. One sample

will be made using sugar, corn syrup and water, while the other will be made with just sugar and

water. Each batch of candy for the samples will be a total of 200 grams.

2.

The following pairings will be assigned to different groups:a.10% sugar, 80% karo and 10% water vs. 10% sugar, 90% water

b.20% sugar, 70% karo and 10% water vs. 20% sugar, 80% water

c.30 % sugar, 60% karo and 10% water vs. 30% sugar, 70% water

d.40% sugar, 50% karo and 10% water vs. 40% sugar, 60% water

e.50% sugar, 40% karo and 10% water vs. 50% sugar, 50% water

f. 60% sugar, 30% karo and 10% water vs. 60% sugar, 40% water

g.70% sugar, 20% karo and 10% water vs. 70% sugar, 30% water

h.80% sugar, 10% karo and 10% water vs. 80% sugar, 20% water

i. 0% sugar, 90% karo and 10 % water vs. 90% sugar, 10% water

3. Record these percents on lab worksheet along with the calculated weights of each based on the 200

gram total for each sample.

4. Weigh out each of the ingredients by placing an empty beaker on the scale and tearing it. From

there add the appropriate amounts of ingredients. Record data

5. Mix all ingredients together in a beaker with a spoon and place on hot plate with a thermometer set

to degrees Celsius. A cookie sheet placed under the hot plate may be helpful for unexpected spills.

6. Turn hot plate on Medium-High heat

7. The candy may be stirred BEFORE boiling to test for clearing but once boiling has begun DO NOT stir

the candy or it may initiate crystallization. Record clearing temperature and boiling temperature

Difference between boiling and

clearing of solution

sugar

Distilled water

Corn syrup

Hot plate with beaker

Digital thermometer

Measuring

cu s s oons

Rimmed cookie sheet

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8. Keep an eye on the temperature since it will spike as the water content decreases. Test candy at

116C, 130C, 140C and 145C by the ball method of dropping a tiny bit of candy into a bowl of cold

water. Retest at 150C if hard tack temperature has not been reached. Candy will pop during

quenching when hard candy has been achieved. Taste to check

9.

When hard candy temperature has been reached the hot plate needs to be turned off and beakerremoved using hot pads.

10. Cast the molten candy to make the following samples:

a. quenched sample by pouring into the bowl of cold water (enough to fill test tube for DTA)

b. Enough molds for a class set (one mold for each group of 4)

c. One thin mold to place on a microscope slide to view crystals.

Silicon acts as a great mold since candy will peel out

easily without any mess

d. Leave a small amount of candy in beaker to be used for fiber drawing.

i. Take a wooden stirrer and try to pull the longest chain possible while the candy cools.

Leave this fiber on a paper towel for students to observe.

Example of fibers that are created when pouring the

candy solution and what can be formed when drawing

fibers.

11. Beakers and utensils must be cleaned using hot water to dissolve any leftover candy. Lab benches

must also be wiped down with a hot rag or paper towel.

12. Get into assigned groups of 4 and start observing the different % sugar samples. Observe each of

the samples, in order, on a rating of 1-10.

a. Transparency (10 being most transparent)

b. # of crystals ( 10 being 0 crystals)

c. Color (10 being clear to no color)

d. Ability to form fibers (10 being longest fibers formed easily)

e. Hardness (10 being the smallestimpression)

a. Using a paper clip see how deep you can push the wire into the

candy when cooled completely.

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DTA procedure to find the glass transition temperature of candy (Day 5 of lesson)

1. Once done making and observing candy, each group must find the Tgof the samples using a

homemade DTA. Each group of 4 will find the Tgof the two quenches samples made previously (the

sugar and water mixture and the sugar, water and corn syrup mixture).

2. Obtain all the materials needed for the DTA apparatus and start setting up set up

Figure 29: multimeter set-up [21]

Figure 30: DTA set-up [21]

3. The beaker must be filled to the 1000 mL line of the 1500 mL beaker with vegetable oil.

4. The test tube on the left, the reference tube, must also be filled with vegetable oil to the same line as

the vegetable oil in the beaker.

5. The right test tube, the sample tube, must be filled to the same line with the sample being measured.

6. The thermocouple must be placed in both test tubes above the bottom of the test tube but below the

surface of the material.

Figure 9: thermocouple placement [21]

Figure 32: multimeter set-up [21]

7. The wire from the sample must go to the positive terminal, in line with the black wire, of the

multimeter while the other goes to the negative terminal (standard convention)

8. The leads of the multimeter should be plugged into the circuit board in line with the coordinating

colored wire from the circuit.

Left: Black in

line with black

Left side: positive

Place this wire in

sample test tube

Measuring in

volts

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9. Turn on the multimeter to get a good base line measurement. The measurements should be taken

every 30 seconds by use of a timer (the time taker should be responsible for this). The

measurements that need to be taken are the differential temperature, measured in volts, and the

bath temperature in degree Celsius. (Two other lab partners can be responsible for each of these).9. The data should be recorded until a second base line is achieved after boiling as begun.

10. During data recording, the last lab partner should be responsible for any observations inside the test

tube. The observations that should be noted are the time and temperature of:

a. When the candy starts to soften (use wooden kabob stick to poke samples often)

b. When the candy starts to melt (melting temperature)

i. signs include widening of the test tube along with cracks and gaps starting to heal

ii. Observe the physical differences before and after melting

c. When the candy starts to break away from the soldered wire (causes jump in data)

d. When the candy starts to boil

11. Turn off the multimeter and let the apparatus cool down before attempting to clean up.

12. Graph your data on an excel graph and label the Tm, Tgand Tbof the candy.

13. Compare results, along with classmates, to a phase diagram for sugar water. (Try making your own if

possible)

a. Compare the temperature where the candy softened to the glass transition temperature.

b. Note what phase candy is in below and above the melting point line (liquid (syrup) or liquid

plus sugar)

c. Compare the boiling point temperature to the boiling point curve.

d. Compare the solubility curve to when the candy turned clear both when making it and

during the DTA testing.

Figure 33: sugar/water phase diagram with boiling point [19]

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Lesson PlansDay 1: Lesson on Ceramics and Glass

Anticipatory set: Have students look around the room and list any application of glass

they see in the room (students can then add more that they know of)

o Make a list of the properties that glass has (pass around an example for students

to feel and manipulate, but make sure students dont break it!) (see appendices)

o See if students can explain why they have the properties that they do. What

makes glass different than all other materials?

Lesson on the history, production, properties, and application of glass (see background)

o When students get to the structure part of sand (silica) students can make their

own models with Styrofoam balls and toothpicks (see paper under appendices)

o When talking about amorphous solids have students play a quick game of

musical chairs (give students a set amount of time to get back to seats in order

to show a slower cool down versus a faster cool down of molecules)

Day 2: Glass stations labAnticipatory set: Show students a piece of glassware that has been bent for use in a

laboratory apparatus. Ask students how it got bent in that direction. Do the same thing

with a drinking bottle and again ask the students how the bottle got its shape.

Have students go through the different glass stations keeping in mind any safety

precautions. Have students record their data and fill out worksheets (see appendices).

Day 3: Lesson on Edible glass and how it compares to Soda-lime glass

Anticipatory set: Give each student a jolly rancher or a life saver to make a list of

properties that it has (make sure students dont eat it yet!) (see appendices)

o Compare these properties to the properties made yesterday with glass. How are

they the same? How are they different?Lesson on the production of hard candy including the structure, production, ways to

inhibit crystal growth, and glass transition temperature (see background)

o Have students play musical chairs again but this time have half the kids act as

corn syrup molecules by holding hands and blocking students from getting to

their seats (this is dependent on the maturity of the class).

o When students are talking about glass transition temperature have students

compare a piece of gum to their jolly rancher. What are the differences?

Have the students chew the gum and label more differences

Have the students put an ice cube in their mouth with the gum to cool it

down. What happens to the gum?

Students should realize that the gum got hard, or reached its glass

transition temperature which is around 0-37C [20].

Day 4 and 5: Candy making lab followed by the analysis of their candy using the DTA

Have students pair up and begin making their candy being careful of the safety

precautions. Make sure they cover the candy so humidity doesnt destroy them

overnight. Run the DTA experiment the next day. Record data (see appendices).

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**Optional: Students can extend this activity further by observing all the different candy

samples the students made and producing their own candy based on what they think the

optimal sample was. Students can make lollipop molds of this candy and put a project

together trying to advertise and sell their candy based on what they learned in class.

Other extensions for this lab are as follows:

Using Snells law to find the refractive index of candy (Physics application)

Annealing and tempering glass and candy to see the affects of hardness

Discussing how animals and plants use sugar as a way to prevent ice from

crystallizing in their cells (cytoplasm) when placed in cold environments (Biology).

See website:http://www.doitpoms.ac.uk/tlplib/biocrystal/index.php

References

1. "Department of Materials Science & Engineering." Department of Materials Science &

Engineering. Department of Materials Science & Engineering, n.d. Web. 17 July 2012.

http://www.materials.cmu.edu/

2. Wansbrough, Heather. Glass Manufacture. N.p.: n.p., n.d. PDF. Web 19 July 2012.

3. Heffner, Bill. Candy Glass Making Demonstration for Classroom or Science Activity.Bethlehem,

Pennsylvania: Lehigh University, n.d. PDF. Web 7 July 2012.

4. Davis, Raymond E., Regina Frey, Mickey Sarquis, and Jerry L. Sarquis. "Matter and ItsProperties." Modern Chemistry. Austin: Holt, Rinehart and Winston, 2006. 8. Print.

5. Lloyd, Robin. "Scientists Reveal Why Glass Is Glass." Msnbc.com. Msnbc Digital Network, 23 June

2008. Web. 09 Aug. 2012.

.

6. Structure of Amorphous Materials. N.p.: Rensselaer, n.d. PPT. Web 23 July, 2012.

7.

Best, Ben. "LESSONS FOR CRYONICS FROM METALLURGY AND CERAMICS."LESSONS FORCRYONICS FROM METALLURGY AND CERAMICS. N.p., 1990. Web. 26 July 2012.

.

8. "Solidification." Solidification. NDT Resource Center, 17 July 2012. Web. 09 Aug. 2012.http://www.ndt-ed.org/EducationResources/CommunityCollege/Materials/Structure/solidification.htm
http://www.doitpoms.ac.uk/tlplib/biocrystal/index.phphttp://www.doitpoms.ac.uk/tlplib/biocrystal/index.phphttp://www.doitpoms.ac.uk/tlplib/biocrystal/index.phphttp://www.materials.cmu.edu/http://www.materials.cmu.edu/http://nzic.org.nz/ChemProcesses/inorganic/9A.pdfhttp://www.lehigh.edu/imi/pdf/CandyGlassRecipe.pdfhttp://www.lehigh.edu/imi/pdf/CandyGlassRecipe.pdfhttp://www.lehigh.edu/imi/pdf/CandyGlassRecipe.pdfhttp://www.rpi.edu/~keblip/Structure/Structure.amorphous1.ppthttp://www.rpi.edu/~keblip/Structure/Structure.amorphous1.ppthttp://www.rpi.edu/~keblip/Structure/Structure.amorphous1.ppthttp://www.rpi.edu/~keblip/Structure/Structure.amorphous1.ppthttp://www.rpi.edu/~keblip/Structure/Structure.amorphous1.ppthttp://www.rpi.edu/~keblip/Structure/Structure.amorphous1.ppthttp://www.rpi.edu/~keblip/Structure/Structure.amorphous1.ppthttp://www.rpi.edu/~keblip/Structure/Structure.amorphous1.ppthttp://www.ndt-ed.org/EducationResources/CommunityCollege/Materials/Structure/solidification.htmhttp://www.ndt-ed.org/EducationResources/CommunityCollege/Materials/Structure/solidification.htmhttp://www.ndt-ed.org/EducationResources/CommunityCollege/Materials/Structure/solidification.htmhttp://www.rpi.edu/~keblip/Structure/Structure.amorphous1.ppthttp://www.lehigh.edu/imi/pdf/CandyGlassRecipe.pdfhttp://nzic.org.nz/ChemProcesses/inorganic/9A.pdfhttp://www.materials.cmu.edu/http://www.doitpoms.ac.uk/tlplib/biocrystal/index.php

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9. Bunnell, L. Roy.A Physical Model to Help Students Understand the Melting Range of Glasses.

Kennewick, Washington: Southridge High School, n.d. PDF.

10.ASM International, The ASM Materials Camp for Teachers STEM Handbook, 2012, 2012,

http://www.asminternational.org/portal/site/www/foundation/stemhandbook/

11.Baxter, Roberta, Glass: An Amorphous Solid, ChemMatters, 1998, Vol. 26, No. 3, pp. 1011.

12.Corning Museum of Glass, A Resource on Glass, 20022011, 2011,

http://www.cmog.org/dynamic.aspx?id=264

13.Chandler, David L. "Explained: Bandgap." MIT's News. Massachusetts Institute of Technology, 23

July 2010. Web. 23 July 2012. .

14.Meza, Juan M., Mara C. Mor Farias, Roberto Martinz De Souza, and Luis J. Cruz Riao. "SciELO -

Scientific Electronic Library Online." SciELO - Scientific Electronic Library Online. Pontifical

Bolivarian University, Oct.-Nov. 2007. Web. 09 Aug. 2012.

.

15.Bachman, Mark. Glass Etch Wet Process. Irvine: UCI Integrated Nanosystems Research Facility,

Summer 2000. PDF.

16."Science of Candy: What Is Sugar? | Exploratorium." Exploratorium: The Museum of Science, Art

and Human Perception. Exploratorium, n.d. Web. 12 July 2012.

.

17.Pomeroy, Josh. Edible Glass. N.p.: CCMR Educational Programs, n.d. PDF.

18."The Water Sucrose System." - TLP Library Avoidance of Crystallization in Biological Systems.

University of Cambridge, 2012. Web. 12 July 2012.

.

19.Heffner, William R., and Himanshu Jain. Building a Low Cost Hands-on Learning Curriculum for

Glass Science and Engineering Using Candy Glass. Bethlehem, Pennsylvania: Lehigh University,

2010. PDF.

20."Polymer Chemistry: The Glass Transition." Polymer Chemistry: The Glass Transition. Universityof South Carolina, 11 July 2000. Web. 23 July 2012. .

21.Heffner, Bill. Differential Thermal Analysis. Bethlehem, Pennsylvania: Lehigh University, 23 Apr.

2008. PDF.

***Special thanks to Dr. Heffner for all his help in his expertise with the

DTA including preparing a circuit for me. **

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AppendicesPart I: Glass

Applications: Write down some example of glass and how they can be used

1. ________________________________________________________

2. ________________________________________________________

3. ________________________________________________________

4. ________________________________________________________

5. ________________________________________________________

Properties: What are some properties of glass (Before and After lab)

Before Lab

Color: ________________________________________________________

Texture: ______________________________________________________Hardness: _____________________________________________________

Other: ________________________________________________________

_____________________________________________________________

After Lab

______________________________________________________________

______________________________________________________________

______________________________________________________________

Glass Task Sheet [10]

Final Conclusion QuestionsFinal write-up/discussion points:

Directions: Write the answers in your lab notebook and not on this page. Restate the

questions in your answers.

Scoring and Breaking Glass:

What was easy about the process?

What was difficult about the process?

Discuss strength of glass under tension and compression and how this applies to scoring and

breaking glass.

State 4 rules about scoring/breaking technique

Glass Bending/Blowing/Drawing a Fiber

Difference between tubing and rod

How to score tubing/rod

What is the purpose of fire polishing and how is it done

Advantage of fiber optics for communication

What happens to glass as it gets hotter (Hint: phase change?)

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Glass Task Sheet [10]

Scoring and Breaking Glass

5 4 3

Method

Illustration of final productObservations/critique of cuts

Final write-up/discussion

Glass Bend

5 4 3

Method

Illustration of final product

Observations


Glass Fiber5 4 3

Method

Length of final product

Observations


Glass Bubble

5 4 3

Method

Illustration of final product

Observations


Final Product

Points Bonus

Glass Scoring and Breaking

Glass Bend

Glass Fiber

Glass Bubble

Glass Beads on a Wire

Clean-Up

Station Signature

ALL Glass put in waste bin

Goggles put away

Bench wiped off

Materials put back

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Optional Structural Lab for Glass [9]: See website for details on this optional activity

Part II: Candy

Properties: What are some properties of candy?

Before Lab Candy versus Glass?

____________________________________

____________________________________

_____________________________________

______________________________________

Glass transition temperature: properties of the gum before and after ice cube?

Before (during chewing) After (once ice cube was applied)

Data

Sucrose and Water solution Sucrose, Water and Corn syrup solution

Weight percent____% sucrose, ___% water ____% sucrose, 10% water, ____% Corn Syrup

sucrose (g)

water (g)corn syrup (g)

Total weight (g) ______ /200 g ______ /200 g

Boiling Temperature __________ C Boiling Temperature __________ C

Clearing Temperature __________C Clearing Temperature __________C

Candy Task Sheet

Answer questions in lab notebook with question written out

Making Candy:

What was easy about the process? What was difficult?

Discuss the main difference between the two solutions upon heating?

At what temperature did the solution boil? Was this above boiling point of water? Explain.

What were the differences in texture between each ball test? How did you know it was done?

How did your candy match up to the phase diagram of sucrose and water?

Similarities Differences

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116 130 140 145 ______ (?)

Observation of Candy: Fill out Data Table in lab notebook

Weight%

Transparency(10 for clear)

# of crystals(10 being none)

Fiber Drawing(10 for longest)

Color(10 for clear)

Hardness(10 for smallest

impression )

Total

10 sucrose

20 sucrose

30 sucrose

40 sucrose

50 sucrose

60 sucrose

70 sucrose

80 sucrose

90 sucrose

90 syrup

80 syrup

70 syrup

60 syrup

50 syrup

40 syrup

30 syrup

20 syrup

10 syrup

Winner: _____________________________

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Final Conclusion Questions

Final write-up/discussion points:

Directions: Write the answers in your lab notebook and not on this page. Restate the

questions in your answers.

Observing the Candy

Which sample turned out the best based on your ratings?

Which sample had the least amount of crystals? Why?

Why do you think your candy contained crystals?

What was the former, modifier, and stabilizer in the candy solution?

How were the fibers that you drew from the candy comparable to the fibers drawn with glass?

Observations during the DTA analysis

What was the easiest part of this lab? Hardest?

What was your x-axis? (dependent variable) What was your y-axis? (independent variable)

What was theTg

you analyzed from the graph? Is this good for hard candy quality?

How did your observations, or changes, compare to the phase diagram of sucrose and water?

Suggestions and Tips for TeachersWhen taking temperature make sure students are putting the tip of the thermometer in the

middle of the syrup instead of on the bottom and sides of the glass. They want the temperature

of the candy not the hot plate or the glass

Hot plates should be set to Medium-High heat so students dont burn the candy mixture. My hot

plate was set to 330 to start and then 450 once I got used to the procedure.

Keep a beaker of very hot water at each station so students can keep their testing spoons,

thermometers, testing stick, ect. Clean. Make sure students dont double dip these pieces of

equipment into their candy which could contaminate their tests.

As mentioned earlier a plastic spoon could work better to test the candy since the metal spoons

will steal the heat of the candy and cause jumps in the temperature. This might scare the

students thinking they did something wrong.

Higher sucrose content solutions will be very thick and will look totally different than higher

corn syrup mixtures. Let students know this so they dont think they did something wrong with

the ingredient amounts.

Difference between high sucrose, left, and

high corn syrup, right., upon boil ing.

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When obtaining data for the DTA analysis DO NOT let students move the beaker full of hot

vegetable oil. If they want a cooling curve the teacher should remove the beaker of oil while the

students carefully put a pot on the hot pad. Then the teacher can place the beaker of oil in the

pot. Ice and water should then be added to the pot while the vegetable oil cools. If done quicklyenough the students wont have a delay in their data.

DO NOT use any other glass other than Pyrex. With the fast changes in temperature any other

glass might shatter or break which would case a lot of injuries.

No other chemicals and or experiments should be preformed with these beakers and hot plates

since students will be using these to eat. Try to keep these pieces of equipment set aside so

there is no fear of contamination with chemicals.

Educational Standards used and/or met

National Educational Technology Standards

CONTENT STANDARD A: SCIENCE AS INQUIRY

A1. Abilities necessary to do scientific inquiry:

Identify questions and concepts that guide scientific investigations.

Design and conduct a scientific investigation.

Use technology and mathematics to improve investigations and communications.

Formulate and revise scientific explanations and models using logic and evidence.

Recognize and analyze alternative explanations and models.

Communicate and defend a scientific argument.

A2. Understanding about scientific inquiry:

Scientists usually inquire about how physical, living, or designed systems function.

Scientists conduct investigations for a wide variety of reasons.

Scientists rely on technology to enhance the gathering and manipulation of data.

Mathematics is essential in scientific inquiry.

Scientific explanations must adhere to criteria such as a proposed explanation must be

logically consistent; it must abide by the rules of evidence; it must be open to questions

and possible modification; and it must be based on historical and current scientific

knowledge.Results of scientific inquiry emerge from different types of investigations and public

communication among scientists.

CONTENT STANDARD B: PHYSICAL SCIENCE

B1. Structure of atoms

B2. Structure and properties of matter

B3. Chemical reactions

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B4. Motions and forces

B5. Conservation of energy and increase in disorder

B6. Interactions of energy and matter

CONTENT STANDARD C: LIFE SCIENCE (yes with biology extension)C1. The cell

C2. Molecular basis of heredity

C3. Biological evolution

C4. Interdependence of organisms

C5. Matter, energy, and organization in living systems

C6. Behavior of organisms

CONTENT STANDARD E: SCIENCE AND TECHNOLOGY

E1. Abilities of technological design:

Identify a problem or design an opportunity.

Propose designs and choose between alternative solutions.

Implement a proposed design.

Evaluate the solution and its consequences.

Communicate the problem, process, and solution.

E2. Understanding about science and technology:

Scientists in different disciplines ask different questions, use different methods of

investigation, and accept different types of evidence to support their explanations.

Science often advances with the introduction of new technologies.Creativity, imagination, and a good knowledge base are all required in the work of

science and engineering.

Science and technology are pursued for different purposes.

G2. Nature of scientific knowledge:

Science distinguishes itself from other ways of knowing and from other bodies of

knowledge.

Scientific explanations must meet certain criteria.

Because all scientific ideas depend on experimental and observational confirmation, allscientific knowledge is, in principle, subject to change as new evidence becomes

available.

2012 corcoran

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