Introduction to Introduction to SolutionsSolutions

Guiding QuestionsGuiding Questions

Vocabulary to look for:Vocabulary to look for: Solution, viscosity, alloy, solvent, solute, Solution, viscosity, alloy, solvent, solute,

electrolyte, nonelectrolyte, suspension, electrolyte, nonelectrolyte, suspension, colloid, solubility, saturated solution, colloid, solubility, saturated solution, unsaturated solution, supersaturated unsaturated solution, supersaturated solution. solution.

What 4 factors affect the rate of What 4 factors affect the rate of dissolving?dissolving?

What 3 things affect a substance’s What 3 things affect a substance’s solubility?solubility?

Definition: SOLUTIONDefinition: SOLUTION

A system in which one or more A system in which one or more substances are homogenously mixed substances are homogenously mixed or dissolved in another substance.or dissolved in another substance.

In other words: two chemicals mixed In other words: two chemicals mixed together completely. together completely.

Can result in a solid, liquid, or gasCan result in a solid, liquid, or gas

What are some What are some examples?examples?

ShampooShampoo Soft drinksSoft drinks Air Air GasolineGasoline steelsteel

What do you need to make What do you need to make a solution?a solution?

Example: Kool-aid, basically sugar waterExample: Kool-aid, basically sugar water

1) solute—part being dissolved (sugar)1) solute—part being dissolved (sugar) 2) solvent—part doing dissolving (water)2) solvent—part doing dissolving (water)

+ =

A True SolutionA True Solution

PropertiesProperties

1) mixture is homogenous and the 1) mixture is homogenous and the ratios of solvent to solute can be ratios of solvent to solute can be varied. varied.

In Kool-aid example, more or less sugar In Kool-aid example, more or less sugar could be added to make the solution could be added to make the solution more or less concentrated.more or less concentrated.

A True SolutionA True Solution

PropertiesProperties

2) The dissolved solute is molecular 2) The dissolved solute is molecular or ionic in size.or ionic in size.

The sugar in the packet dissolves into The sugar in the packet dissolves into separate sugar moleculesseparate sugar molecules

A True SolutionA True Solution

PropertiesProperties

3) It is either colorless 3) It is either colorless

or transparent (not cloudy)or transparent (not cloudy)

A True SolutionA True Solution PropertiesProperties

4) The solute is uniformly distributed 4) The solute is uniformly distributed and doesn’t settle out over time.and doesn’t settle out over time. After an hour, the solution should still After an hour, the solution should still

look the same. No chunks at the look the same. No chunks at the bottom or top…think of hot chocolate bottom or top…think of hot chocolate when it sits for a whilewhen it sits for a while

A True SolutionA True Solution

PropertiesProperties

5) The solute can be separated from 5) The solute can be separated from the solvent by physical means the solvent by physical means (evaporation, filtration, boiling, etc)(evaporation, filtration, boiling, etc)

Recall the first lab where we boiled salt Recall the first lab where we boiled salt water, after the water evaporated, the water, after the water evaporated, the salt was left at the bottom. salt was left at the bottom.

SuspensionSuspension A mixture in which particles ofA mixture in which particles ofa material are dispersed through-a material are dispersed through-out a liquid or gas but are largeout a liquid or gas but are largeenough that they settle out.enough that they settle out.

Particles are insoluble, so they DO NOT Particles are insoluble, so they DO NOT dissolve in the liquid or gas.dissolve in the liquid or gas.

Particles can be separated using a Particles can be separated using a filter.filter. Examples:Examples: Muddy WaterMuddy Water Salad dressingSalad dressing Medicines that say “shake well before use” Medicines that say “shake well before use”

ColloidsColloids A mixture in which the particles are A mixture in which the particles are

dispersed throughout but are not heavy dispersed throughout but are not heavy enough to settle out.enough to settle out. Made up of solids, liquids and gases.Made up of solids, liquids and gases. The particles of which the colloid is made are The particles of which the colloid is made are

called the dispersed material. called the dispersed material. Any colloid consisting of a solid dispersed in a gas Any colloid consisting of a solid dispersed in a gas

is called a smoke. is called a smoke. A liquid dispersed in a gas is referred to as a fog.A liquid dispersed in a gas is referred to as a fog. Some colloids: Mayonnaise, colored glass , milkSome colloids: Mayonnaise, colored glass , milk

Colloids can be made from almost Colloids can be made from almost any combination of gas, liquid, and any combination of gas, liquid, and

solid.solid.

Dissolving Dissolving

How do substances dissolve?How do substances dissolve?

DiffusionDiffusion

Molecules travel from areas of high Molecules travel from areas of high concentration to areas of low concentration to areas of low concentration.concentration.

SolubilitySolubility describes how likely one describes how likely one substance will dissolve in another.substance will dissolve in another.

SolubilitySolubility

Amount of solute that can dissolve in Amount of solute that can dissolve in the solvent.the solvent. Very solubleVery soluble Moderately solubleModerately soluble Slightly solubleSlightly soluble insolubleinsoluble

How can I make a solute How can I make a solute dissolve faster?dissolve faster?

(1)INCREASE THE TEMPERATURE(1)INCREASE THE TEMPERATURE for liquids, this causes the solvent for liquids, this causes the solvent

molecules to move faster and bump into the molecules to move faster and bump into the solute particles more often and harder, solute particles more often and harder, breaking them apart faster.breaking them apart faster.

(2) AGITATION OR STIRRING(2) AGITATION OR STIRRING this physically helps the solute particles this physically helps the solute particles

diffuse by distributing them to all parts of diffuse by distributing them to all parts of the solvent.the solvent.

(3)BREAK IT DOWN(3)BREAK IT DOWN The smaller the particle, the faster it The smaller the particle, the faster it

dissolvesdissolves

How can I make a solute How can I make a solute dissolve faster?dissolve faster?

(4) CONCENTRATION(4) CONCENTRATION The closer you get to the saturation The closer you get to the saturation

point, the slower the dissolving occurspoint, the slower the dissolving occurs The solute dissolves quickly at first The solute dissolves quickly at first

because there is a lot of area to dissolve because there is a lot of area to dissolve intointo

As more of the solute dissolves, the As more of the solute dissolves, the area shrinks and dissolving slows down.area shrinks and dissolving slows down.

What Affects a Substance’s What Affects a Substance’s Solubility? Solubility?

Question:Question:

When making Jell-o, why do the When making Jell-o, why do the directions tell you to pour the packet directions tell you to pour the packet into hot water and then cool it?into hot water and then cool it?

Why can’t you just pour it in Why can’t you just pour it in cold water and then drink it right cold water and then drink it right away?away?

What Affects a Substance’s What Affects a Substance’s Solubility?Solubility?

(1) Temperature(1) Temperature For For LIQUIDSLIQUIDS::

Solutes dissolve faster in warmer Solutes dissolve faster in warmer solventssolvents

More solute can be dissolved if you More solute can be dissolved if you use warm solvents.use warm solvents.

Why?Why? The KMT of course (Kinetic The KMT of course (Kinetic

Molecular Theory)Molecular Theory)

Which one would dissolve Which one would dissolve more salt?more salt?

100 C 50 C

How much more would the first cup dissolve?

Solubility CurvesSolubility Curves

Can use a graph to represent Can use a graph to represent solubilitysolubility

Y-axis = grams of solute per 100g Y-axis = grams of solute per 100g HH22OO

X-axis = temperatureX-axis = temperature Different substances will have different Different substances will have different

curves on the graph.curves on the graph.

What’s happening with HCl, NH3, and SO2 (dotted lines)

Solubility of GasesSolubility of Gases

The solubility of gases decreases The solubility of gases decreases with increasing temperatures.with increasing temperatures.

Can you think of a situation where Can you think of a situation where this principle is illustrated? (hint: this principle is illustrated? (hint: many of you have one at lunch time)many of you have one at lunch time)

SODASODA

SODASODA

Cold soda is more fizzy because Cold soda is more fizzy because more gas is dissolved in the soda.more gas is dissolved in the soda.

Why does soda become flat as it Why does soda become flat as it warms to room temperature? warms to room temperature? (remember the KMT)(remember the KMT) As the soda becomes warm, the gas As the soda becomes warm, the gas

molecules begin to move faster and molecules begin to move faster and evaporate out of the soda.evaporate out of the soda.

(2) Solubility & Pressure(2) Solubility & Pressure

Changes in pressure have the largest Changes in pressure have the largest effect on gases dissolved in liquids.effect on gases dissolved in liquids.

Pressure and solubility vary directly.Pressure and solubility vary directly.

As the pressure increases, the As the pressure increases, the solubility increases.solubility increases.

Back to the SodaBack to the Soda

Why does a can of soda fizz when it’s Why does a can of soda fizz when it’s opened?opened?

Canned at high pressures.Canned at high pressures. When it’s opened, the pressure inside is When it’s opened, the pressure inside is

reduced to the atmospheric pressure, reduced to the atmospheric pressure, and the excess dissolved COand the excess dissolved CO22 bubbles bubbles out of the sol’n.out of the sol’n.

(3) The Nature of the (3) The Nature of the Solute and the SolventSolute and the Solvent

Explain why water and oil do not Explain why water and oil do not mix?mix?

Like dissolves likeLike dissolves like Polar substances dissolve in other Polar substances dissolve in other

polar substances and nonpolar polar substances and nonpolar dissolve in nonpolar.dissolve in nonpolar.

Oil is nonpolar and water is polar.Oil is nonpolar and water is polar.

Nonpolar vs. PolarNonpolar vs. Polar

When nonpolar substances dissolve When nonpolar substances dissolve in one another, they simply mix.in one another, they simply mix.

When polar substances dissolve, When polar substances dissolve, electrical reactions pull apart the electrical reactions pull apart the molecules.molecules.

Saturated, Unsaturated, & Saturated, Unsaturated, & Supersaturated Sol’nsSupersaturated Sol’ns

SATURATEDSATURATED Holds the maximum amount of solute in the Holds the maximum amount of solute in the

dissolved state dissolved state No more solute can be added and still No more solute can be added and still

dissolve.dissolve. UNSATURATEDUNSATURATED

More solute could be added and still More solute could be added and still dissolve.dissolve.

SUPERSATURATEDSUPERSATURATED Holds more solute than the max.Holds more solute than the max. Very unstable and have to be prepared in a Very unstable and have to be prepared in a

special way. special way.

SUPERSATURATEDHolds more solute thanthe max. Very unstableand have to be prepared in a special way.

Supersaturated SolutionsSupersaturated Solutions

Hand/foot warmer packs used for Hand/foot warmer packs used for cold weather are examples.cold weather are examples.

Activated when they are crushedActivated when they are crushed The heat generated is a result of the The heat generated is a result of the

supersaturated solution coming out supersaturated solution coming out of supersaturation. This reaction is of supersaturation. This reaction is exothermicexothermic..

Cold packs work the same way but Cold packs work the same way but are are endothermicendothermic reactions. reactions.

Stop hereStop here

Will a solution made by adding 2.5g of Will a solution made by adding 2.5g of CuSOCuSO44 to 10g of H to 10g of H22O be saturated or O be saturated or unsaturated at 20°C?unsaturated at 20°C? Use the curve on slidesUse the curve on slides Find the solubility of CuSOFind the solubility of CuSO4 4 at 20°at 20°

It is 21g per 100g HIt is 21g per 100g H22OO

This is equivalent to 2.1g CuSOThis is equivalent to 2.1g CuSO44 per 10g per 10g HH22O O

Since 2.5 is greater than 2.1, the sol’n will Since 2.5 is greater than 2.1, the sol’n will be saturated. How much will be be saturated. How much will be undissolved?undissolved?

.4g .4g

You TryYou Try

Will a sol’n made by adding 9.0g Will a sol’n made by adding 9.0g NHNH44Cl to 20g of HCl to 20g of H22O be saturated or O be saturated or unsaturated at 50°C?unsaturated at 50°C?

unsaturatedunsaturated

Solution ConcentrationSolution Concentration

Equations to learnEquations to learn (1) Mass Percent(1) Mass Percent (2) Mass/Volume Percent(2) Mass/Volume Percent (3) Volume Percent(3) Volume Percent (4) Molarity(4) Molarity (5) Dilution (5) Dilution

Mass %Mass %

g solute *g sol’n = g solute + g g solute *g sol’n = g solute + g solvent solvent

g sol’ng sol’n

•For example a 10% sugar solution would For example a 10% sugar solution would contain 10g sugar for every 100g sol’n.contain 10g sugar for every 100g sol’n.

•Can use this equation to figure out how Can use this equation to figure out how much of a 16oz can of soda is sugar (40%, much of a 16oz can of soda is sugar (40%, 50%??)50%??)

Practice ProblemsPractice Problems

(1) what is the mass % of sodium (1) what is the mass % of sodium hydroxide in a solution that is made by hydroxide in a solution that is made by dissolving 8.00g NaOH in 50.0g Hdissolving 8.00g NaOH in 50.0g H22O?O?

g solute = 8.00 gg solute = 8.00 g g solvent = 50.0 gg solvent = 50.0 g g sol’n = 58.0 gg sol’n = 58.0 g 8.00 g NaOH8.00 g NaOH

58 g solution = .138 = 13.8 % NaOH 58 g solution = .138 = 13.8 % NaOH sol’nsol’n

Practice ProblemsPractice Problems (2) What masses of potassium chloride (2) What masses of potassium chloride

and water are needed to make 250. g and water are needed to make 250. g of 5.00% solution?of 5.00% solution?

g sol’n = 250. g sol’n = 250. Mass % = 5.00Mass % = 5.00 X g KClX g KCl

250. g sol’n 250. g sol’n

•(250. g) x (.0500) = (250. g) x (.0500) = 12.5 g KCl 12.5 g KCl (solute)(solute)

•250. g sol’n – 12.5 g KCl = 250. g sol’n – 12.5 g KCl = 238 g H238 g H2200

= .0500

Practice ProblemsPractice Problems

(3) A 34.0% sulfuric acid sol’n has a (3) A 34.0% sulfuric acid sol’n has a density of 1.25 g/mL. How many density of 1.25 g/mL. How many grams of Hgrams of H22SOSO44 are contained in 1.00 L are contained in 1.00 L of this sol’n?of this sol’n?

425g H425g H22SOSO44

Mass/Volume PercentMass/Volume Percent

g soluteg solute

mL solutionmL solution

What does a 10% glucose solution What does a 10% glucose solution suggest?suggest?

The solution has 10g of glucose per The solution has 10g of glucose per 100ml sol’n.100ml sol’n.

ExampleExample

A 3.0% HA 3.0% H22OO22 solution is commonly solution is commonly used as a topical antiseptic to used as a topical antiseptic to prevent infection. What volume of prevent infection. What volume of this solution will contain 10. g of this solution will contain 10. g of HH22OO22??

.03 = 10. g solute/ X.03 = 10. g solute/ X X = 330 mL solution X = 330 mL solution

Volume %Volume %

Solutions formed between 2 liquidsSolutions formed between 2 liquids Common measure for alcoholic Common measure for alcoholic

beveragesbeverages PROOF = twice the volume percentPROOF = twice the volume percent Pure alcohol is 100% and therefore 200 Pure alcohol is 100% and therefore 200

proofproof Scotch whiskey is 86 proof… volume % = ?Scotch whiskey is 86 proof… volume % = ? 43% alcohol43% alcohol

volume of liquid in questionvolume of liquid in question

total volume of solutiontotal volume of solution

MolarityMolarity

M = molesM = moles LLA 6 M HCl solution contains 6 moles A 6 M HCl solution contains 6 moles

of HCl for every Liter of solution.of HCl for every Liter of solution.

What does a 5.7 M solution contain?What does a 5.7 M solution contain?

5.7 moles of HCl for every Liter of 5.7 moles of HCl for every Liter of solution.solution.

ExamplesExamples

1- What is the molarity of a solution 1- What is the molarity of a solution containing 1.4 mol of acetic acid in containing 1.4 mol of acetic acid in 250 mL of solution?250 mL of solution?

250mL = .250 L move decimal 250mL = .250 L move decimal 33 placesplaces

1.4 mol / .250 L = 1.4 mol / .250 L = 5.6 M5.6 M

More ExamplesMore Examples

2- What is the molarity of a solution 2- What is the molarity of a solution made by dissolving 7.50 g of made by dissolving 7.50 g of magnesium nitrate in enough water magnesium nitrate in enough water to make 25.0 mL of solution?to make 25.0 mL of solution?

2.02 M2.02 M

One moreOne more

3- How many grams of sodium 3- How many grams of sodium chloride are needed to prepare 125 chloride are needed to prepare 125 mL of a 0.037 M NaCl solution?mL of a 0.037 M NaCl solution?

0.27 g NaCl0.27 g NaCl

DilutionDilution

100mL water

6 moles NaCl

200mL water

6 moles NaCl

The moles are the same in The moles are the same in each glasseach glass

Because they contain the same Because they contain the same amount of moles, we can use:amount of moles, we can use:

MM11VV11 = M = M22VV2 2 M=molarityM=molarity

oror CC11VV11 = C = C22VV2 2 C=concentration C=concentration

ExamplesExamples

Calculate the molarity of a solution Calculate the molarity of a solution prepared by diluting 125 mL of prepared by diluting 125 mL of 0.400 M K0.400 M K22CrCr22OO77 with 875 mL of with 875 mL of water.water.

(125)(.400) = (1000) M(125)(.400) = (1000) M22

.05 M .05 M