Apologia Chemistry Module 11 Test Review

1.

The substance being dissolved is the...

A.

Solution
B.

Solute
C.

Solvent
D.

Percipitate

Correct Answer
B. Solute

Explanation
The solvent (usually water) is the substance dissolving the solute. The solution is the solute and the solvent together. The percipitate is a substance that doesn't dissolve.

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2.

The solubility of a solute depends on...

A.

The identity of the solute.
B.

The identity of the solvent.
C.

Both are correct

Correct Answer
C. Both are correct

Explanation
Like dissolves like. It's easiest for ionic compounds to dissolve in ionic solvents.

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0

1

3.

If we increase the temperature of a solution and more solute dissolves, then the solute is a solid.

A.

True
B.

False

Correct Answer
A. True

Explanation
Think about sugar in tea

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4.

If the solubility of a solute isn't affected by temperature, the solute is a...

A.

Solid
B.

Liquid
C.

Gas

Correct Answer
B. Liquid

Explanation
If the solubility of a solute isn't affected by temperature, it means that the solute remains equally soluble at different temperatures. Liquids are generally more soluble than solids or gases because their particles are already in a dispersed state, making it easier for them to mix with the solvent. Therefore, if the solute is not affected by temperature, it is likely to be a liquid.

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5.

The reason that the hot Dr. Pepper exploded with more force after we shook it up is because...

A.

The solubility of gases decrease with increasing temperature.
B.

The solubility of gases increase with increasing temperature.

Correct Answer
A. The solubility of gases decrease with increasing temperature.

Explanation
The hot Dr. Pepper couldn't dissolve as much gas as the cold one. That's why it spewed when we shook then opened it.

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6.

Exothermic reactions become...

A.

Cold.
B.

Hot.
C.

Pressurized.

Correct Answer
B. Hot.

Explanation
Exo means out. Therm means heat. Endothermic reactions become cold.

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7.

Put these in order of ability to raise a liquid's boiling point from least to greatest.

A.

They would all raise the boiling point the same.
B.
C.
D.

Correct Answer
C.

Explanation
NH3 is a covalent molecule so it doesn't break into ions. It's i is 1. NaCl's i is 2, and K2CO3's i is 3.

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8.

Write this equation down. We'll use the same equation in several questions. We want to make 50 grams of KCN. How many moles is this?

A.

1.30 moles
B.

0.768 moles
C.

5.28 moles

Correct Answer
B. 0.768 moles

Explanation
Got grams? Want moles? Divide by the AMU.

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9.

How many moles of HCN are used during the reaction if 0.768 moles of KCN are produced?

A.

One-half as many
B.

The same amount
C.

Twice as many

Correct Answer
B. The same amount

Explanation
Make a proportion with the moles over the balancing numbers. Then solve for the moles of HCN.

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10.

If used 0.768 moles of HCN and made it from a 1.51 M solution of HCN, how many liters did I use?

A.

0.509 Liters
B.

4.31 Liters
C.

0.287 Liters

Correct Answer
A. 0.509 Liters

Explanation
Remember that molarity is Moles/Liters so moles/Molarity = Liters

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11.

Change to ml: 0.509 Liters

A.

0.000509 ml
B.

50.9 ml
C.

509 ml

Correct Answer
C. 509 ml

Explanation
To change liters to milliliters, multiply by one thousand. Here is the original question: How many ml of a 1.51 M solution of HCN would be required to make 50.0 grams of potassium cyanide? Know these steps from these questions!

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12.

Check all that are true.

A.

To find molality, you need to know how many moles you have.
B.

To find molality, you need to know the mLs of the solute.
C.

To find molality, you need to know the weight of the solvent.
D.

Molality is used to find the boiling point elevation.
E.

Molality is used to find the freezing point depression.
F.

Molality is used to find the ions in a solute.
G.

Molality is a concentration unit.

Correct Answer(s)
A. To find molality, you need to know how many moles you have.
C. To find molality, you need to know the weight of the solvent.
D. Molality is used to find the boiling point elevation.
E. Molality is used to find the freezing point depression.
G. Molality is a concentration unit.

Explanation
The correct answer is: To find molality, you need to know how many moles you have.,To find molality, you need to know the weight of the solvent.,Molality is used to find the boiling point elevation.,Molality is used to find the freezing point depression.,Molality is a concentration unit.

Molality is a concentration unit that is defined as the number of moles of solute per kilogram of solvent. Therefore, to find molality, you need to know how many moles of solute you have and the weight of the solvent. Molality is used to calculate the boiling point elevation and freezing point depression, which are colligative properties of a solution. Additionally, molality is a concentration unit that expresses the amount of solute in a given amount of solvent.

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13.

To find the molality if you have grams of solute and g of solvent...

A.
B.

Correct Answer
A.

Explanation
grams/AMU gets moles. grams/1000 gets kg. Molality is moles/kg.

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14.

Delta T = i K m is the formula for freezing point depression.

A.

True
B.

False

Correct Answer
B. False

Explanation
This is the formula for boiling point elevation. The freezing point depression formula has a negative in front of the i.

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15.

When 7.5 grams of NaCl are added to 100.0 grams of water, what is the change in the water's freezing point? molality of water = 1.86

A.

9.52 degrees C
B.

4.76 degrees C
C.

-4.76 degrees C
D.

-9.52 degrees C

Correct Answer
C. -4.76 degrees C

Explanation
Delta T =( - 2) (1.86)((7.5 grams/58.5 moles)/0.1 kg of water))

i = 2 for NaCl because it breaks into 1 Na ion and 1 Cl ion.
Remember to change the 100 grams of water into Kg by dividing by 1000.

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16.

If the delta T from the last question is -4.76, what is the water's new freezing point?

A.

27.24
B.

0
C.

-4.76
D.

95.24

Correct Answer
C. -4.76

Explanation
Since water freezes at 0 degrees C, 0-4.76=-4.76.
Be careful! Delta T is not always the final temperature only when you're using water and calculating freezing point.

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