Deck 11: Solutions

Question 1

115.0 grams of calcium chloride are weighed out and placed into a 1.5 L volumetric flask and the flask filled to the mark. What is the concentration of the calcium chloride solution?

A) 0.6433 M
B) 0.6907 M
C) 0.4380 M
D) 1.014 M

Answer 1

B

Question 2

96.5 grams of an unknown substance were diluted with water in a 1.000 L volumetric flask. It was determined that the concentration of the substance was 1.22 M. What is the molar mass of the unknown substance?

A) 117 g·mol^-1
B) 79.1 g·mol^-1
C) 1.26×10^-2 g·mol^-1
D) 65.4 g·mol^-1

Answer 2

B

Question 3

Equal volumes of ethanol (C₂H₅OH) and water are mixed. If the density of water is 1.00 g·cm^-3 and that of ethanol is 0.789, what is the mole fraction of ethanol in the mixture?

A) 0.764
B) 0.309
C) 0.324
D) 0.236

Answer 3

D

Question 4

120.0 grams of calcium nitrate are weighed out and placed into a 1.5 L volumetric flask and the flask filled to the mark. What is the concentration of the nitrate ions in solution?

A) 0.9751
B) 0.4875
C) 1.026
D) 2.051

Question 5

50.0 grams of sodium benzoate (mw 144.1053 g·mol^-1) is diluted into enough water to give a 0.95 molal solution. If the density of the solution is .985 g·cm^-3, what is the mass of water that was added?

A) 502 grams
B) 1000 grams
C) 365 grams
D) 415 grams

Question 6

Find the (integer) stoichiometry coefficients for the correctly balanced version of the following reaction:
Cr₂O₇^2-(aq) + H⁺(aq) + I^-(aq) → Cr³⁺(aq) + H₂O(l) + I₃^-(aq)

A) 1, 14, 1, 2, 1, 7
B) 1, 14, 1, 1, 1, 7
C) 2, 1, 7, 1, 1, 5
D) 1, 14, 9, 2, 7, 3
E) none of these

Question 7

Find the (integer) stoichiometry coefficients for the correctly balanced version of the following reaction:
IO₃^-(aq) + S₂O₃^2-(aq) + H⁺(aq) → I^-(aq) + S₄O₇^2-(aq) + H₂O(l)

A) 1, 3, 3, 1, 3, 3
B) 6, 2, 6, 6, 1, 3
C) 2, 3, 3, 1, 1, 9
D) 2, 6, 6, 2, 3, 3
E) none of these

Question 8

Some sodium hydroxide pellets were placed in an Erlenmeyer flask and dissolved in approximately 50 ml of water. This solution was then transferred to a buret. 3.00 ml of 1.0 molar nitric acid was diluted into approximately 50 ml of water in another flask. It required 22.67 ml of the sodium hydroxide solution to titrate the dilute nitric acid solution to an endpoint. What can you say about the mass of sodium hydroxide pellets initially added to the Erlenmeyer flask?

A) more than a gram was used
B) less than a gram was used
C) exactly a gram was used
D) not enough information is provided to answer the question

Question 9

How many ml of 0.1506 M NaOH are required to reach the endpoint in a titration with 30.00 ml of 0.2215 M HCl?

A) 20.40
B) 30.15
C) 31.18
D) 44.12

Question 10

Which, if any, of the following would you expect to readily dissolve in water?

A)

B)

C)

D) a and c
E) none of the above

Question 11

According to the Arrhenius theory, which of the following is a base?

A) BH₃
B) C₂H₅OH
C) Ca(OH)₂
D) b and c
E) None of the above

Question 12

An unknown amount of toluene (bp 110.6 C) and benzene (bp 80.1 C) are mixed and the vapor pressure over the mixture measured. 100 grams of toluene is then added to the mixture and the vapor pressure measured again. Will the new vapor pressure be:

A) The same as the original vapor pressure
B) Higher than the initial vapor pressure
C) Lower than the initial vapor pressure
D) Not enough information is given to answer the question

Question 13

A mixture is prepared by mixing 100.0 grams of ethanol (C₂H₆O) with 30.0 grams of acetone (C₃H₆O). At 25°C the vapor pressures of pure ethanol and acetone are 59 Torr and 231 Torr respectively. What will be the total vapor pressure over the mixture at this temperature?

A) 212 Torr
B) 62 Torr
C) 92 Torr
D) 88 Torr

Question 14

Exhibit 11-1
The following question(s) pertain to the mixing of lead nitrate and sodium sulfate to form a lead sulfate precipitate.
Refer to Exhibit 11-1. Which of the following represents a balanced net ionic chemical equation for this reaction?

A) Pb(NO₃)₂(aq) + 2NaSO₄(aq) → PbSO₄(s) + 2NaNO₃(aq)
B) Pb²⁺ (aq) + 2NO₃^-(aq) + 2Na⁺(aq) + SO₄^2-(aq) → PbSO4(s) + 2Na⁺(aq) + 2NO₃^- (aq)
C) Pb²⁺ (aq) + SO₄^2-(aq) → PbSO4(s)
D) Pb(NO₃)₂(aq) + Na₂SO₄(aq) → PbSO₄(s) + 2NaNO₃(aq)

Question 15

Exhibit 11-1
The following question(s) pertain to the mixing of lead nitrate and sodium sulfate to form a lead sulfate precipitate.
Refer to Exhibit 11-1. What are the spectator ions in this reaction?

A) Nitrate and lead
B) Nitrate and sodium
C) Nitrate and sulfate
D) Sulfate and lead

Question 16

On a per-mole basis, which of the following, when dissolved in water, will lower the freezing point most?

A) NaCl
B) FeCl₃
C) MgCl₂
D) NH₄NO₃

Question 17

30.0 g of a binary salt is dissolved in enough water to give a final volume of 800.0 ml. The freezing point of the water drops by 2.40°C. What is the molar mass of the binary salt?

A) 58.0 g·mol^-1
B) 74.5 g·mol^-1
C) 118 g·mol^-1
D) Not enough information given to answer the question
E) None of the above

Question 18

What is the expected boiling point of a solution made by combining 400.0 g of water with 100.0 g of Na₂CO₃?

A) 103.6°C
B) 113.5°C
C) 101.2°C
D) 104.8°C

Question 19

Exhibit 11-2
The following question(s) pertain to the dissolution of 200.0 g of KMnO4 into 600.0

A) 1.255 m
B) 2.109 m
C) 1.054 m
D) 2.223 m
G) of water.
Refer to Exhibit 11-2. What is the molality of the KMnO₄ in the 800.0 gram solution?

Question 20

Exhibit 11-2
The following question(s) pertain to the dissolution of 200.0 g of KMnO4 into 600.0

A) 0.0353
B) 0.0365
C) 0.0433
D) 0.0333
G) of water.
Refer to Exhibit 11-2. What is the mole fraction of MnO₄^- ions in the solution?

Question 21

Exhibit 11-2
The following question(s) pertain to the dissolution of 200.0 g of KMnO4 into 600.0

A) 2.58 M
B) 2.69 M
C) 1.29 M
D) 0.897 M
G) of water.
Refer to Exhibit 11-2. If the density of the new solution is 1.02 g·cm^-3, what is the molarity of potassium ions in the solution?

Question 22

Exhibit 11-2 The following question(s) pertain to the dissolution of 200.0 g of KMnO₄ into 600.0 g. of water.
Refer to Exhibit 11-2. If 200.0 ml of a solution that was 0.20 M in KMnO₄ were added to the 800.0 g solution, would you expect the boiling point of that solution to go up? 

A) Yes
B) No
C) More data is needed to answer the question

Question 23

A dilute sugar solution (0.0025 M) is separated from pure water by a semipermeable membrane so that an osmotic pressure is established. What is the osmotic pressure at 25°C?

A) 123 Torr
B) 0.0645 Torr
C) 46.4 Torr
D) 12.3 Torr

Question 24

110.5 grams of a biological compound is dissolved in 500 ml of water? The compound is observed to have an osmotic pressure of 97.4 Torr at 28°C. What is the molecular mass of the compound?

A) 42600 g·mol^-1
B) 85200 g·mol^-1
C) 121 g·mol^-1
D) 97.5 g·mol^-1

Question 25

At 20°C chloroform (mw 119.38 g/mol) has a vapor pressure of 159 Torr. When 50.0 grams of an unknown compound is mixed with 100.0 grams of chloroform at 20°C the vapor pressure of chloroform over the mixture drops to 69.1 Torr. What is the molecular mass of the added compound?

A) 70.1 g·mol^-1
B) 139 g·mol^-1
C) 77.7 g·mol^-1
D) 45.9 g·mol^-1
E) More information is needed to answer the question

Question 26

What can you say about the oxidation number of carbon in the following compounds?

A) It is positive
B) It is negative
C) It is the same as oxidation number of oxygen
D) b and c
E) a and c

Question 27

In the following chemical reaction,
CO + 3 H₂ → CH₄ + H₂O
The oxidation number of carbon:

A) Decreases by 1
B) Increases by 1
C) Decreases by 2
D) Increases by 2
E) More information is needed to answer the question

Question 28

Commercial sulfuric acid (H₂SO₄) is 18.4 M in concentration. How much sulfuric acid is contained in 51 mL of this solution?

A) 0.36 mol
B) 0.94 mol
C) 3.6 mol
D) 9.4 mol
E) none of these

Question 29

To prepare 0.250 L of a 0.115_M NaBr solution, a technician must mix

A) 0.115 moles of NaBr with 0.250 L of H₂O.
B) 0.115 moles of NaBr with 0.250 kg of H₂O.
C) 0.115 moles of NaBr with enough H₂O to produce 0.250 kg of solution.
D) 0.115 moles of NaBr with enough H₂O to produce 0.250 L of solution.
E) none of these

Question 30

320 mL of 1.00 M HCl(aq) is combined with 1.18 L of 0.125 M HCl(aq) to give a total volume of 1.50 L. The molarity of the HCl in the final solution is

A) 0.562 M
B) 0.468 M
C) 0.312 M
D) 0.175 M
E) none of these

Question 31

A mixture of solid NaCl and CaCl₂ contains 10.0 g of NaCl, and an unknown amount of CaCl₂.  When the entire mixture is dissolved in 1.00 kg of water, the boiling point changes by 0.25 ºC.  What mass of CaCl₂ was in the original mixture? Kb for water is 0.512 K. kg . mol⁻¹. 

A) 5.4 g
B) 8.1 g
C) 35.2 g
D) Not enough data to answer the question
E) None of the above

Question 32

Acetone (mw = 58.08, P25 C=232 mmHg) and butanone (mw = 72.11, P 25 C=100 mmHg) have the indicated molar masses and vapor pressures.  A container holds 1.00 kg of butanone.  How much acetone must be added to the butanone to elevate the total vapor pressure over the mixture to 125 mmHg at 25°C?

A) 5.313 kg
B) 290 g
C) 188 g
D) More information needed
E) None of the above

Question 33

How many milliliters of 0.1500 M CaCl₂ must be added to 100.00 milliliters of 0.4000 M KCl to give a final solution that has [Cl-] = 0.3500 M? 

A) 70.0 ml
B) 100 ml
C) 125 ml
D) 200 ml
E) None of the above