Technological Institute of the Philippines938 Aurora Blvd., Cubao, Quezon City

Chemistry Laboratory Experiment No. 1

BASIC LABORATORY OPERATIONS

Submitted By:

Group No. 4 of Section ES11KA1

Leader: Abesamis, Ranma A.

Members: Austria, Lucas C. Cas, Mark Vergel C. Ladanga, Erycka Joie S. Soledad, John Kenneth P. Tabo, Jacob Jewel C. Vertucio, Rupert H.

Submitted To:

Engr. Nessie L. Dela Torre

TS YSFRONT PAGE 10OBJECTIVES 5THEORYAPPARATUS 5PROCEDURESDATA & RESULTSOBSERVATION 15CONCLUSION 20QUESTIONS & ANSWERSSCORE

Date Performed: 21 June 2012 Date Submitted: 28 June 20121. OBJECTIVES

Familiarize with the basic laboratory operations; Practice the basic laboratory operations; and Develop the skill to light and properly adjust the Bunsen burner flame.

2. THEORY

Laboratory operations are the collection of procedures made useful in the conduct of laboratory experiments in chemistry and other natural science courses. There are a lot of laboratory operations ranging from simple to complicated ones. All laboratory operations have to be done carefully and attentively in order to achieve the desired objectives of the activity (Anomalous.2009).

The basic laboratory operations used in the chemistry laboratories are: Bunsen burner operations, volumetric measurement, density determination and separation of precipitates.

Bunsen Burner Operation

A Bunsen burner is a laboratory device designed to heat substances for various experiments. It is a small gas burner with an adjustable flame, manipulated at the base by controlling the amount of gas and air admitted into the burner.

Bunsen burner includes a vertical metal tube which is connected to a weighted base. The base includes a nozzle to connect with a fuel source, as well as a gas valve and a flue adjuster to control how much air is admitted through small air holes at the base of the tube. The gas mixes with air at the bottom of the tube and then rises to the top of the Bunsen burner, where it can be lit with a match or lighter.

Bunsen burner reflects the name of the scientist supervising the laboratory where it was invented, rather than the actual inventor. Robert Wilhelm Bunsen was a well known chemist in Germany in the mid 1800s, searching for a way to provide clean, safe heat in his laboratory. One of his laboratory assistants, Michael Faraday, invented a gas burner to assist them with experiments, and another lab assistant, Peter Desaga, refined the invention, calling the result a Tirrill burner. This burner allowed for greater control over the flame’s height and intensity, and it quickly became associated with Bunsen’s laboratory. As a result, it became popularly known as a Bunsen burner. (www.wisegeek.com)

Parts of the Bunsen Burner

a. gas orifice - allows the exit of gas into the barrel.b. barrel - part where the gas and air mix.

c. collar - regulates the flow of air entering the burner.- controls the size of the flame.

d. air holes - vary the amount of air entering the barrel. A flame with “roaring” soundmeans that too much air is entering the burner. If the flame “strikesback” and burns noisily at the base of the burner, it means that there isnot enough gas pressure and too much air. Turn-off the gas cock andstart again.

The combustible gas used to supply the fuel for the Bunsen burner in most laboratories is a natural gas in which natural gas is a mixture of gaseous hydrocarbon. If sufficient oxygen is supplied, gas burns with a blue, non-luminous flame, producing carbon dioxide and water as combustion products.

With an insufficient supply of oxygen, small carbon particles are produced when heated to incandescence and produce a yellow luminous flame. The combustion product includes carbon dioxide, carbon monoxide and water.

Measuring Liquid Volumes

A liquid is usually measured by the use of graduated cylinder, burette or pipette. The liquid surface is noticeably curved (www.sciencerey.com). The curve is referred to as the meniscus and in reading the liquid volume, it is necessary to have the meniscus at the eye level.

Transferring Liquid

In transferring liquid from one container to another, pour the liquid down a glass rod to prevent spills. For small quantities, use a pipette.

Heating Liquids

When heating a liquid in a test tube, tilt glassware at a 45-degree angle, with the open point of a tube not pointing to a person. Heat first the upper portion of the tube, then slowly move it back and forth from the flame. Heating other glassware such as a beaker needs a tripod and a wire gauze.

Precipitation

Precipitation is defined as the formation of a solid in a solution during the occurrence of a chemical reaction.

Filtration

Filtration is a technique used to isolate solid or impurities from a solution. There are two types of filtration, the gravity filtration and vacuum filtration. The former is best in removing impurities from a solution and the latter when collecting a desired solid. In gravity filtration, proper folding of the filter paper must be observed.

Decantation

Decantation is a very quick method used for separating a mixture of a liquid and a heavier solid. First allow the solid to settle at the bottom, then pour off the liquid.

Centrifugation

Centrifugation is a process that involves the use of centrifugal force for the separation of mixtures. The more dense component of the solution migrates away from the axis of the centrifuge while the less dense component migrate towards the axis. A centrifuge machine is used for this process.

Evaporation

Evaporation is the process of changing liquid to gas or vapor. Heat (energy) is necessary for evaporation to occur. Energy is used to break the bonds that hold solvent molecules together.

3. APPARATUS

1 – beaker 1 – meter stick1 – Bunsen burner 1 – reagent bottle1 – clay triangle 1 – rectangular block1 – cork borer 1 – spatula1 – Erlenmeyer flask 1 – stirring rod1 – evaporated dish 1 – test tube with rack1 – filter paper 1 – triple beam balance1 – funnel 1 – watch glass1 – graduated cylinder1 – iron ring1 – iron stand

4. PROCEDURES

A. Bunsen Burner

A.1. Dismantle the burner and study the parts.

A.2. Reassemble the burner and connect the rubber tubing to the gas outlet. Be surethat it is tightly fitted to the gas outlet and the gas inlet to the burner. To lightthe burner, unscrew the ring collar to allow the gas to enter and light matchstick, hold the lighted match stick above the barrel and turn open the gas supplyvalve. Note the color of the flame produced with the air holes closed.

A.3. Hold an evaporating dish using a crucible tong above the flame. Observe thebottom of the dish.

A.4. Open the air holes gradually and observe that the flame changes color.

A.5. Hold the evaporating dish on top of the flame produced in step four.

If we look at the flame when the air holes are open, we shall see that there aretwo cones, an inner cone which is blue and an outer one which is bluish purple.The space within the inner cone is filled with a mixture of gas and air. This mixture is partially burned at the tip of the inner cone and completely burnedabove the region. The space in the inner cone contains unburned gas.

A.6. Thrust a pin on a match and suspend it on top of the burner.

A.7. Into each of the three test tubes, measure 2 ml of H2O. Label the test tubes T1,T2, and T3. Using a test tube holder, hold test tube T1 in a 450 angle positionfrom the part of the flame just above the barrel. Record the time, in seconds, it takes the water to boil.

A.8. Bring test tube T2 to the tip of the inner cone. Record the time it takes the waterto boil. Do the same for test tube T3 but hold on the tip of the outer cone.Record your data.Interpret the results.

B. Volumetric Measurement

B.1. Reading a Meniscus

In getting the reading of the measured liquid, one must set the eye in horizontallevel with the liquid. For transparent liquid (colorless), always read the bottom ofthe meniscus, for colored liquid, take the upper meniscus. Get your sample from

your instructor.

B.2. Using graduated cylinder measure 2 ml of water and transfer the water into thetest tube. Determine its height in centimeters. Repeat with 4 ml, 6 ml, 8 ml and10 ml.

B.3. Repeat step B.2 using a colored liquid.

C. Density Determination

Density is one of the physical properties of matter which is the ratio of mass per unitvolume.

Mathematically, M D = --- V

Where:

M = mass, gramV = volume, mlD = density, g/ml

Since mass like volume requires measurement, it is therefore important to beacquainted with the use of the laboratory balances. For general laboratory use andapproximate weighing, the triple beam balance is used. (The instructor will firstdemonstrate and discuss the use of the triple beam balance).

C.1. Solid Density (Regular Solid)

To determine the density of a regularly shaped solid, like rectangularparallelpiped, sphere and cylinder, we need to calculate using the definitemathematical formula. The weight of the object is determined by the use of thebalance. Get a rectangular block from the stockroom. Measure its dimension andrecord the measurements.

For a rectangular block, the volume is determine by getting the productof the length, width and height.

C.2. Liquid Density

C.2.1. Weigh an empty 100 ml beakerC.2.2. Pour 50 ml of lead nitrate solution into the beakerC.2.3. Weigh the beaker with the lead nitrate solutionC.2.4. Determine the weight of the solution by subtracting the weight of empty

beaker from the weight of beaker with the lead nitrate solution.C.2.5. Determine the density of lead nitrate solution

D. Separation of Precipitates

D.1. Filtration

This is the process of straining the precipitate with the use of a filterpaper.

Prepare the set-up.

D.1.1. Place the iron stand on your working table.D.1.2. Get an iron ringD.1.3. Clamp the iron ring to the iron stand about one foot above the top of

the table.D.1.4. Place a clay triangle.D.1.5. Place a funnel in the clay triangle on the iron ring.D.1.6. Place a beaker on the platform of the iron stand as a receiver.D.1.7. The tip of the funnel must rest on the wall of the beaker. (Make

necessary adjustment if it is too high).D.1.8. Prepare a filter paper

a. Fold the filter paper equally in halfb. Fold again through the center, but half of the crease must not

coincide with the other half of the creasec. Tear off the corner of the outside foldd. Open out

e. Moisten the filter paper with water.f. Place the filter paper in the funnel.

D.1.9. Prepare a solution by adding 10 g Ca(OH)2 to 50 ml waterD.1.10. Pour the mixture into the filter with the aid of a Glass rod

D.2. Decantation

This is a simpler process by allowing the mixture to stand for quitesometime to settle the precipitate. This process is good for precipitates that arequite dense. The liquid is now poured off and the precipitate will be left behind.

D.2.1. Add 20 g Ca(OH)2 to 100 ml waterD.2.2. Let the solution stand for several minutesD.2.3. Decant the solution

D.3. Evaporation

D.3.1. Dissolve 0.1 g of sodium chloride to 1 ml waterD.3.2. Transfer the solution to an evaporating dishD.3.3. Place the dish on a wire gauze supported by iron ringD.3.4. Heat gentlyD.3.5. Withdraw the heat as soon as the water is evaporatedD.3.6. Note the residue left

5. DATA & RESULTS

A. Bunsen Burner

A.1. What is the flame called? Blue-colored flame

A.2. What is deposited at the bottom of the dish? Hot flame residue

A.3. What do you call this flame?Bluish-purple-colored flame

A.4. Is there any deposited substance at the bottom of the dish?Charcoal-like residue or substance which is even hotter

A.5. Why does the match head not ignited at once?It is because the pin acts as a barrier which prevents the ignition of the match head.

A.6.

TEST TUBE TIME (seconds)T1 30 secondsT2 15 seconds T3 45 seconds

B. Volumetric Measurement

Data

Water Colored LiquidVolume Height Volume Height

2 ml 1.4 cm 2 ml 1.4 cm4 ml 2.6 cm 4 ml 2.6 cm6 ml 4.3 cm 6 ml 4 cm8 ml 5.4 cm 8 ml 5.5 cm

10 ml 6.8 cm 10 ml 7 cm

C. Density Determination

C.1. Solid Density (Regular Solid)

Weight of the block 173.4 gLength of the block 11.9 cmWidth of the block 6.2 cmHeight of the block 3.2 cmVolume of the block 236.096 cm 3 Density of the block 0.734 g/cm 3

C.2. Liquid Density

Weight of the empty beaker 95.6 gWeight of beaker with lead nitrate 114.9 gWeight of lead nitrate 19.3 gVolume of lead nitrate solution 20 mlDensity of lead nitrate solution 0.965 g/ml

6. OBSERVATION

A. Filtration

We observed that during the filtration process, the water(H2O) is being separated slowly from calcium hydroxide(Ca(OH)2) through the help of a filter paper. We have to wait for a long time to filter.

B. Decantation

During the decantation process, the calcium hydroxide(Ca(OH)2) was decanted or separated from water(H2O) after being stand for at least 5 minutes. This happened because in some way, calcium hydroxide is way denser than water.

C. Evaporation

During the evaporation process, we observed that the water(H2O) evaporated while leaving the residue which is sodium chloride inside the evaporating dish while being heated gently by the Bunsen burner.

7. CONCLUSION

Therefore, we conclude that in this experiment, each and every one of the laboratory apparatus has its own functions, uses, and capabilities in order for the experiments regarding chemistry to be conducted successfully while maintaining the accuracy and precision of measurements and procedures. In this experiment, we were also able to determine the density of different matters and their distinguished properties. Lastly, we were able to observe the different ways of separating precipitates while using different mediums.

8. QUESTIONS & ANSWERS

8.1. What is combustion?

Combustion is defined as the burning of a fuel and oxidant to produce heat and work. It is the ability of a compound to burn in oxygen. It is the major energy release mechanism in the Earth and the key to humankind’s existence. Combustion includes thermal, hydrodynamic, and chemical processes.

8.2. What are the types of combustion? Differentiate each.

a. Complete Combustion - In complete combustion, the reactant burns in oxygen, producing a limited number of products. When a hydrocarbon burns in oxygen, the reaction will only yield carbon dioxide and water. When elements are burned, the products are primarily the most common oxides. Carbon will yield carbon dioxide, nitrogen will yield nitrogen dioxide, sulfur will yield sulfur dioxide, and iron will yield iron(III) oxide.

b. Incomplete Combustion - Incomplete combustion will only occur when there is not enough oxygen to allow the fuel to react completely to produce carbon dioxide and water. It also happens when the combustion is quenched by a heat sink such as a solid surface or flame trap. For most fuels, such as diesel oil, coal or wood, pyrolysis occurs before combustion. In incomplete combustion, products of pyrolysis remain unburned and contaminate the smoke with noxious particulate matter and gases. Partially oxidized compounds are also a concern; partial oxidation of ethanol can produce harmful acetaldehyde, and carbon can produce toxic carbon monoxide.

c. Smoldering type of Combustion - Smoldering is the slow, low-temperature, flameless form of combustion, sustained by the heat evolved when oxygen directly attacks the surface of a condensed-phase fuel. It is a typically incomplete combustion reaction. Solid materials that can sustain a smoldering reaction include coal, cellulose, wood, cotton, tobacco, peat, duff, humus, synthetic foams, charring polymers including polyurethane foam, and dust. Common examples of smoldering phenomena are the initiation of residential fires on upholstered furniture by weak heat sources (e.g., a cigarette, a short-circuited wire), and the persistent combustion of biomass behind the flaming front of wildfires.

d. Rapid Combustion - Rapid combustion is a form of combustion, otherwise known as a fire, in which large amounts of heat and light energy are released, which often results in a flame. This is used in a form of machinery such as internal combustion engines and in thermobaric weapons. Sometimes, a large volume of gas is liberated in combustion besides the production of heat and light. The sudden evolution of large quantities of gas creates excessive pressure that produces a loud noise. Such a combustion is known as an explosion. Combustion need not involve oxygen; e.g., hydrogen burns in chlorine to form hydrogen chloride with the liberation of heat and light characteristic of combustion.

e. Turbulent Combustion - Combustion resulting in a turbulent flame is the most used for industrial application (e.g. gas turbines, gasoline engines, etc.) because the turbulence helps the mixing process between the fuel and oxidizer.

f. Microgravity Combustion - Combustion processes behave differently in a microgravity environment than in Earth-gravity conditions due to the lack of buoyancy. For example, a candle's flame takes the shape of a sphere. Microgravity combustion research contributes to understanding of spacecraft fire safety and diverse aspects of combustion physics.

8.3. Describe the basic methods of separating precipitates.

a. Filtration – is the process of separating/straining substances or precipitates with the use of a filter paper.

b. Decantation – is the separating of the substances or precipitates by letting it stand for several minutes. This is a simpler process by allowing the mixture to stand for quite sometime to settle the precipitate. This process is good for precipitates that are quite dense. In this process, the liquid is poured off and the precipitate will be left behind.

c. Evaporation – it is the process of separating precipitates or substances through the vaporization of the liquid. It is a type of vaporization of a liquid that occurs only on the surface of a liquid. The other type of vaporization is boiling, which, instead, occurs on the entire mass of the liquid.

8.4. Label the parts of the Bunsen burner and give their functions.

Parts of the Bunsen Burner:

A. Barrel – where gas and air are mixedB. Collar – adjust the air intakeC. Air Intake Openings – air enters hereD. Gas Flow Valve – regulates flow of gas (can also be controlled from table gas valve)E. Gas Intake Tube – gas enters burner from table sourceF. Base – supports burner