ANSWER KEY a. Whole cube

ANSWER KEY
Exam #9 Review: Solutions, Solubility Curves and Water Chemistry
1. Circle the condition that will cause the sugar to dissolve faster in water:
a. Whole cube
or
granulated sugar?
b. When allowed to stand
or
when stirred?
c. At a higher temperature
or
a lower temperature?
2. Know the difference between saturated, unsaturated and supersaturated. (see definitions)
SATURATED - the exact maximum amount of solute dissolved at a given temperature.
UNSATURATED - less than the maximum amount of solute dissolved at a given temperature.
SUPERSATURATED - more than the maximum amount of solute dissolved; usually very unstable.
3. With the use of the solubility curve graph, determine the type of solution (saturated, unsaturated or
supersaturated) found for each of the following:
a. 10 g of potassium chlorate (KClO3) at 0 °C: supersaturated
b. 20 g of sodium chloride (NaCl) at 20 °C: unsaturated
c. 85 g of potassium nitrate (KNO3) at 50 °C: saturated
4. Solubility Curves:
a. For each substance, look up the temperature at 60°C and give the amount of solubility in grams
that would make the solution SATURATED:
1) sodium chloride (NaCl): ~38 grams
2) potassium chloride (KCl): ~45 grams
b. Which 2 substances have the same degree of solubility at about 30°C? NH3 and KNO3
c. To what temperature would you have to heat 90g of NaNO3 in 100 mL of water to get it to
dissolve completely to make the solution SATURATED? 25°C
d. Which of the substances shown on the solubility curve is the least soluble in water at 70°C? SO2
5. Name the 6 properties of water and an example of each! (SEE WATER NOTES)
mol
6. Using the concentration formula, C = V , calculate for the missing variable.
a. What is the concentration of a solution that has 10 moles of KOH in a 400 mL solution?
C = mol = 10 mol = 25M
V
0.400 L
b. How many moles (X) are in a solution of 2 L with a concentration of 2 M?
C = mol
V
2M=
X
2L
x = 4 mol
7. Using the formula, C1V1= C2V2, calculate the missing variable.
a. You want to have a 2 L of a 0.500 M solution of HCl. What would the original volume (V1)
have been if the original concentration was 10 M? (10 M)(x) = (0.500 M)(2 L)
10x = 1
x (or V1) = 0.1 L
b. You want to have a 500 mL of a 1.50 M solution of HNO3. What would the original volume
(V1) have been if the original concentration was 16 M? (16 M)(x) = (1.5 M)(500 mL)
16x
=
750
x (or V1) = 46.88 mL
8. Identify the following as either miscible or immiscible:
a. Water and vegetable oil - immiscible
b. Water and food coloring - miscible
c. Vegetable oil and food coloring - immiscible
9. Define the following:
a. Solution – homogeneous mixture; can
exist in ANY STATE
b. Solute – the part that is BEING dissolved
c. Solvent – the part that DOES the
dissolving
d. Electrolyte – a substance that conducts
an electrical current in aqueous solution
10. Identify the solute and solvent in each of the following solutions:
a. salt and water make salt water. Solute – salt and solvent - water
b. sugar, lemon juice and water make up lemonade solute- sugar and lemon juice and
solvent - water
c. A few drops of food coloring can change the color water solute – food coloring and solvent
- water
11. Know the parts of a phase change graph and what is happening between each section.