Unit 10 Review

2011

1. Describe the following terms

• Solution

• Solvent

• Solute

• Soluble

• Insoluble

• Miscible

• Immiscible

Homogeneous mixtures of 2 or more substances

Dissolving medium

Substance that dissolves

Will dissolve

Won’t dissolve

Liquids are soluble in one another

Liquids aren’t soluble in one another

2. Examples of the solutions

• Solid in a liquid

• Gas in a liquid

• Solid in a solid

• Gas in a gas

Salt water

Carbonated beverage

Steel/braces

Air

3

• Describe what happens as a crystal of salt (NaCl) dissolves in water.

Charged ends of water are attracted to the ions in salt

This attraction is strong enough to pull the ions away

4

• How is the dissolving process different in sugar (compared with salt)?

OH bonds attract H of H2O molecules until sucrose molecule is surrounded by many H2O molecules, which then pull entire sucrose molecule away

5

• Why doesn’t oil dissolve in water? Would oil dissolve in anything?

Oil is nonpolar and water is polar. Oil would dissolve in a nonpolar solvent.

6

• What is solubility?

Maximum amount of solute that will dissolve in a given amount of solvent at a specific temperature and pressure.

7. How does temp affect solubility?

• For solids?

• For gases?

– What else changes gas solubility?

As temp increases, solubility increases

As temp increases, solubility decreases

pressure

8

• What three things can be done to increase the rate at which a solid dissolves?

a. Agitate the mixture

b. Increase surface area of solute

c. Increase temperature of solvent

9

• Dissolving is a Physical or Chemical change.

PHYSICAL

10

• How would you prepare a supersaturated sugar solution? Include the term “seed crystal”.

Make a saturated solution at a high temperature. Then cool slowly so excess solute remains dissolved at a lower temp. when a seed crystal is added, the entire solution will crystalize.

11

• What is one test you could do to determine if a solution was saturated, unsaturated, or supersaturated? Describe how the results would be different for unsaturated, saturated, supersaturated solutions.

Add more solute: unsaturated solution, it will dissolve

saturated solution, it won’t dissolve

supersaturated solution, a seed crystal will cause the solution to crystallize

12

• Water is known as the:

Universal solvent

13

• What does solution concentration describe?

Molarity: amount of solute dissolved in a given amount of solvent

14

• What do we use to describe solution concentration in chemistry?

Molarity

15

• If a solution is “strong” it is

• If a solution is “weak” it is

concentrated

dilute

16

• What does it mean to dilute a solution? What equation do we use for dilutions?

To lower its concentration “water it down”

M1V1 = M2V2

17

• What is the molarity of a sodium chloride solution that contains 1.73 moles in 3.94 L of solution?

1.730.439

3.94

mol molM M

L L

18

• What is the molarity of sodium hydroxide solution that contains 23.5 g NaOH in 500.0 mL of solution?

1 0.58823.5 1.18

40.00 0.5000

mol molgNaOHx M

g L

19

• How many grams of potassium nitrate are in 275 mL of 1.25 M solution?

1.25 0.3440.275

xM mol

L 3KNO

101.1134.8

1

gx g

mol 3KNO

20

• How many mL of 3.25 M hydrochloric acid would contain 16.0 grams of solute?

116.0 0.439

36.46

molgHClx mol

g

0.4393.25 135

molM mL

x

21

• You have 12.0 M HCl in your stock room, how would you prepare 600.0 mL of 2.50 M HCl solution?

(12.0 M)(x) = (2.50 M)(600.0 mL)

X=125 mL

Measure out 125 mL of stock solution. Add 475 mL of distilled water.

22

• How would you correctly prepare 500.0 mL of a 3.0 M solution of NaOH from solid solute?

3.0 1.50.5000

xM mol

L NaOH

40.0060

1

gx gmol

Measure out 60 g of NaOH (s)

Add water to the 500.0 mL line

23

• How would you prepare 500 mL of 3.0 M NaOH from 12.0 M concentrated stock solution?

(12.0 M)(X) = (3.0 M)(500 mL)

X=125 mL

Measure out 125 mL of stock solution. Add it to 375 mL of distilled water

26

• An excess of zinc is added to 125 mL of 0.100 M HCl solution. What mass of zinc chloride is formed?

Zn + 2HCl ZnCl2 + H2

0.1000.125

xM

L

27

• When determining solubility remember:

“like dissolves like”

28

• Polar/Nonpolar molecules will dissolve in water

Polar

29

• Polar molecules: one of these shapes:

• Must have ______ bonds (electronegativity difference between 0.4-2.1)

Dumbbell, bent, trigonal pyramidal

Polar covalent

30• Molecules that won’t dissolve in water

include anything with ____ bonds (electronegativity differences less than 0.4)

• Symmetrical shapes such as:

• These substances might dissolve in:

nonpolar

Linear, trigonal planar, tetrahedral

Oil

31

• Determine whether or not the following chemicals will dissolve in water. Circle the ones that will

MgCl2 SeO2 SiO2 PCl3

Ionic