Chap 13 notes rearranged.ppt

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CH. 13

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Solution – a

homogeneous mixture of two or more

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Solute – what’s being dissolved

Solvent – what’s doing the dissolving

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Solutions don’t always have to be solid in a liquid.

Gas in liquid or solid in solid (alloys) are also called

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Electrolyte – when dissolved in water, conducts electricity

(NaCl, ionic compounds)

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How can you make a solid dissolve faster?

1. Increase surface area

(cut it into smaller pieces)

2. Agitate solution

(stir or shake it)

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Saturated solution – has the maximum amount of

dissolved solute

(any more you add falls to the bottom)

Unsaturated solution –has less solute than it can hold

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Supersaturated

Solution – contains

more dissolved solute than the solvent can

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“Like dissolves like”

Polar molecules dissolve in polar molecules

Nonpolar dissolve in nonpolar

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Miscible – substances dissolve in one another

(oil in gasoline)

Immiscible –

substances don’t

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As Temp

↑

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As Temp

↑

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As Temp

↑

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As Temp

↑

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As Pressure

↑

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As Pressure

↑

solubility of a gas in

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Solubility – how much

solute is needed to form a saturated solution at

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Solubility of sugar:

204 g

@

20 °C

487 g

@ 100

°C

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Molarity

-A quantitative measure of concentration

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Molarity

.5 M NaOH

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moles of solute Liters of solution

n

LM =

Molarity=

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3.0 M NaOH means there are 3 moles of NaOH

dissolved in 1 Liter of

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Ex. 1 You have 3.5 L of solution that contains

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Ex. 2 You have 0.81 L of a 0.55 M HCl

solution. How many

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Ex. 3 You need 0.75 moles of KNO₃ for a

reaction. What volume of a 6.0 Molar KNO₃

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Ex. 4 What do you need to prepare 100.0 mL of

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HOW CAN YOU MAKE AN EGG FLOAT IN WATER?

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The density of a solution

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What happens to the boiling

point as you add salt to water? What happens to the freezing

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Adding a solute to a pure

substance raises the boiling point and lowers the freezing point of the substance!

(and lowers

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Salt will lower the freezing

point of a solution more than sugar. WHY?

b/c salt is an electrolyte!

NaCl(s)  Na+(aq) + Cl-(aq)

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The more ions in solution the lower the freezing point!

NaCl produces 2 ions but

CaCl₂ produces 3 ions!

NaCl  Na+ + Cl

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Colloids – large particles that “hang” in solvent (not

dissolved) but cannot be

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Tyndall Effect: In a colloid

particles will scatter light and make a light beam “visible”.

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Suspension – very large

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Whenever there is a

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Do you think energy is absorbed or released

when chemical bonds are broken?

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Breaking bonds – endothermic

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If more energy was

released when bonds

were made than took to break them the overall

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OSMOSIS – solvent moving from low to a high concentration

across a semipermeable

membrane (but solute can’t cross the

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Test

Review

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In general,

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Which phase of

matter has the

strongest

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Which phase of

matter has the

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Which phase of

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What are

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What is the property of water called that is responsible for a

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What is it called

when water gets “pulled up” by a

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What will an

increase in

temperature do to

the solubility of a

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What will a

decrease in

temperature do to

the solubility of a

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During sublimation, does energy get

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During freezing, does energy get

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During vaporizaiton, does energy get

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In a solution of 10 g of salt and 50 mL of water, which is the

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A mixture of mud and

water is stirred up and it becomes cloudy.

After 20 minutes the water is clear.

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A mixture of gases consists of 45%

oxygen and 55% carbon dioxide.

Which is the solvent

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Is the following an electrolyte?

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Miscible or

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Saturated or

unsaturated: A

solution of salt water that has some

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The solubility of AgNO₃ at 30 °C is 216 g

AgNO₃ in 100 g water. At this temperature, a

solution of 350 g of AgNO₃ in 100 g of

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Do you expect

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In which mixture are the solute particles biggest, in a

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Miscible or

immiscible:

methanol, a polar

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When dissolving KI in water the beaker

feels cold. Is this an endothermic or

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When solute-solute

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What is the

difference in the

freezing point of a pure solvent and a solution of that

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Which of the

following will lower

the freezing point of water more: KCl,

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As you decrease the pressure above a

solution will CO₂ gas be more soluble or

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Remember:

Homogeneous mixture – perfectly mixed, the

same everywhere

Heterogeneous mixture – has different parts, not

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Ex: 40 mL of salt

dissolved in 500

mL of water.

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Whenever there is a

solution formed there is an energy change!

Exothermic – energy released (-)

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When salt is placed

on icy roads in the

winter time, the ice

gets colder and

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Salt in water:

NaCl(s)  Na+(aq) + Cl-(aq)

Sugar in water: