AP Chemistry Unit 2 Review Questions

How many of the following salts can be expected to be insoluble in water?
- sodium sulfate
- potassium chloride
- ammonium nitrate
- potassium chromate
1. none
2. one
3. two
4. three
5. four
A chemist wants to separate a mixture of salt and fat. He places the mixture in a container with the nonpolar solvent benzene (density = 0.8787 g/cm³) and water (density = 1.00 g/cm³). After shaking the solution and allowing it to settle, the correct arrangement of solvent and solute is:
A 25.0-g sample of sodium hydroxide is dissolved in 400. mL of water. What is the concentration of the solution?
1. 62.5 M
2. 0.10 M
3. 1.56 M
4. 1.56 x 10^-3 M
5. 100. M
How many grams of potassium nitrate are required to prepare 3.00 x 10² mL of 0.750 M solution?
1. 0.00223 g
2. 2.28 x 10⁴ g
3. 2.4 g
4. 22.8 g
5. 84.5 g
How many grams of sodium chloride are dissolved in 50.0 mL of 1.50 M solution?
1. 4.38 g
2. 4.38 x 10³ g
3. 23.4 g
4. 117 g
5. 0.00324 g
A chemist makes a stock solution of potassium chromate solution by dissolving 97.1 grams of the compound in 1.00 liter of solution. What volume of the solution must be diluted with water in order to prepare 200. mL of 0.200 M solution?
1. 0.0800 mL
2. 80.0 mL
3. 120. mL
4. 0.150 L
5. 750. mL
A 500 mL sample of a 0.350 M solution is left open on a lab counter for twl weeks, after which the concentration of the solution is 0.955 M. What is the new volume of the solution?
1. 223 mL
2. 183 L
3. 0.605 L
4. 1.83 mL
5. 0.183 L
All of the following are weak acids except:
1. HNO₃
2. HF
3. H₂CO₃
4. H₂S
5. HClO
In a reaction between ammonium phosphate and silver nitrate in aqueous solution, which of the following terms will be present in the balanced molecular equation?
1. NH₄PO₄(aq)
2. AgNO₃(s)
3. 3NH₄NO₃(aq)
4. Ag₃PO₄(aq)
5. None of these
When solutions of sodium nitrate and potassium chloride are mixed, which of the following will be present in the net ionic equation?
1. Na⁺
2. KNO₃(s)
3. Cl^-
4. NaCl(aq)
5. None of these
Which of the following is the most soluble base?
1. Ba(OH)₂
2. NaOH
3. Ca(OH)₂
4. Mg(OH)₂
5. Al(OH)₃
Which of the following ions is most likely to combine with an anion to form an insoluble salt?
1. sodium
2. sulfide
3. silver
4. potassium
5. ammonium
In the balanced molecular equation for the neutralization reaction between phosphoric acid and potassium hydroxide, the products are:
1. KPO₄ + H₃OH
2. K₃PO₄ + 3H₂O
3. K⁺(aq) + PO₄^3-(aq) + 3H⁺ + 3OH^-
4. 3H₂O
5. None of these
In which of the following compounds does sulfur have an oxidation state of +4?
1. H₂SO₄
2. H₂SO₃
3. H₂S
4. SO₃
5. MgSO₄
What volume of 0.250 M H₂SO₄ is needed to react completely with 14.5 grams of NaOH?
1. 1.45 L
2. 2.90 L
3. 0.237 mL
4. 11.0 L
5. 0.726 L
435 mL of a 0.100 M HNO₃ solution is mixed with 235 mL of 0.175 M Ca(OH)₂. Which of the following statements are true?

1. The solution is alkaline
2. The solution is acidic
3. Water is a product
4. Some HNO₃ remains unreacted
5. Some Ca(OH)₂ remains unreacted
1. 1 and 5
2. 3 and 4
3. 2 and 3
4. 1 and 4
5. 1, 3 and 5
In the reaction 4Al + 3O₂ → 2Al₂O₃ the substance oxidized is:
1. Al
2. O₂
3. Al³⁺
4. O^2-
5. None of these, because this is not a redox reaction
NaCl + H₂SO₄ + MnO₂ → Na₂SO₄ + MnSO₄ + H₂O + Cl₂

In this reaction, the ____ ion is oxidized.
1. Na⁺
2. Cl^-
3. O^2-
4. H⁺
5. Mn⁴⁺
In the following reaction, the oxidation numbers on sulfur are:

NaCl + H₂SO₄ + MnO₂ → Na₂SO₄ + MnSO₄ + H₂O + Cl₂
1. +6, +6 and +4 respectively
2. +4, +6 and +4 respectively
3. +4, +4 and +4 respectively
4. +6, +6 and +6 respectively
5. +4, +6 and +6 respectively
When the following reaction is balanced, the sum of all of the coefficients in the equation is:

NaCl + H₂SO₄ + MnO₂ → Na₂SO₄ + MnSO₄ + H₂O + Cl₂
1. 6
2. 10
3. 11
4. 14
5. 16
You have two samples of the same gas in the same size container, at the same pressure. The temperature in the first container is -23°C and the temperature in the second container is 227°C. What is the ratio of the number of moles of gas in the first container compared to that in the second container?
1. 1:4
2. 4:1
3. 1:1
4. 2:1
5. 1:2
The tires on Mr. Allan's road bike can handle a pressure of 150 psi. What is this pressure in mm Hg? (By the way, these are very expensive tires. Don't do this on your bike at home...or your car!)
1. 775 mm Hg
2. 7.76 x 10³ mm Hg
3. 10.2 mm Hg
4. 1470 mm Hg
5. 760 mm Hg
Which flask contains the greatest number of molecules?
1. Flask 1 (NH₃)
2. Flask 2 (CH₄)
3. Flask 3 (O₂)
4. Flasks 2 and 3
5. All are the same
In which flask do the molecules have the highest average velocity?
1. Flask 1 (NH₃)
2. Flask 2 (CH₄)
3. Flask 3 (O₂)
4. Flasks 2 and 3
5. All are the same
Flask(s) ____________________ is/are most likely to exhibit ideal behavior because ______________________________.
1. Flask 3 (O₂) because it has the greatest molar mass.
2. Flask 1 (NH₃) because it has the lowest molar mass.
3. Flask 1 (NH₃) because ammonia is a polar molecule.
4. Flask 2 (CH₄) because it is a hydrocarbon.
5. Flask 2 and flask 3 because methane and oxygen are nonpolar molecules.
A motorist fills his car tires to 32 lb/in² pressure at a temperature of 30°C. Assuming no change in volume, what will the pressure in the tires be when the motorist drives across Death Valley, with a pavement temperature of 78°C?
1. 83 lb/in²
2. 28 lb/in²
3. 12 lb/in²
4. 37 lb/in²
5. 4.8 lb/in²
An 8.25 L sample of oxygen is collected at 25°C and 1.022 atm pressure. What volume will the gas occupy .940 atm and -15°C?
1. 7.77 L
2. 8.76 L
3. 10.4 L
4. 5.00 L
5. 1.78 L
A valve separates two tanks, one containing 7.6 liters of oxygen at 4.0 atmospheres and the other containing 4.0 liters of carbon dioxide at 11.0 atm. When the valve is opened and the two gases are allowed to come together, what is final pressure?
1. 3.6 atm
2. 9.5 atm
3. 6.4 atm
4. 1.8 atm
5. 8.2 atm
2.50 moles of nitrogen gas is placed in a closed 3.00 liter container at 25°C. If the temperature in the container is raised to 120°C, what will be the change in pressure?
1. 20.4 atm
2. 26.9 atm
3. 12.0 atm
4. 6.5 atm
5. 4.2 atm
The mass of 2.37 liters of a gas is 8.91 grams. What is the density of the gas?
1. 0.266 g/L
2. 3.76 g/L
3. 21.1 g/L
4. 6.54 g/L
5. None of these
325 mL of a gas at STP has a mass of .805 grams. What is the molar mass of the gaseous compound?
1. 55.5 g/mol
2. 0.0555 g/mol
3. 9.04 g/mol
4. 31.7 g/mol
5. None of these
Nitrogen has a molar mass of 28.02 g/mol. What is the density of nitrogen at 1.05 atm and 37°C?
1. 2.82 g/L
2. 1.25 g/L
3. 0.89 g/L
4. 4.72 g/cm³
5. None of these
What is the ratio of the effusion rates of O₂ and SO₂?
1. 0.50
2. 2.0
3. 1.4
4. 0.71
5. None of these
An unknown gas ("A") diffuses at 1.25 times the rate of carbon dioxide at identical conditions of pressure and temperature. What is the molar mass of gas "A"?
1. 64 g/mol
2. 52.2 g/mol
3. 14.0 g/mol
4. 22.0 g/mol
5. 28.2 g/mol
At a temperature of 250K, the molecules of an unknown gas, Z, have an average velocity equal to that of HI at 500K. What is the identity of the gas?
1. NO₂
2. CO₂
3. O₂
4. N₂
5. SO₂
You are given a 1.00-g sample of a dry gas that occupies 1.00 liter at a pressure of 545 Torr and a temperature of 25°C. The sample is bubbled through water at 35°C and collected over water so that the total pressure is 640 Torr and the temperature is 35°C. What will be the observed volume of the wet gas?
1. 0.88 L
2. 1.19 L
3. 2.20 L
4. 0.94 L
5. .099 L
A 3.00 liter mixture of CO₂ and O₂ gas, total pressure 740 Torr and temperature 50°C, is scrubbed with a water spray at 20°C so as to dissolve all the CO₂ and remove it from the gas phase. If the final observed gas volume at 740 Torr and 20°C is 2.50 liters, what percent of the molecules in the original mixture must have been CO₂? Assume that the vapor pressure of water at 20°C is 17.55 mm Hg.
1. 8.2%
2. 10.2%
3. 18.6%
4. 28.1%
5. 50%
How big a volume of dry oxygen gas at STP would you need to take to get the same number of oxygen molecules as there are hydrogen molecules in 25.0 liters at 0.850 atm and 35°C
1. 4.2 L
2. 0.068 L
3. 18.8 L
4. 0.656 L
5. 32.3 L
How many moles of gas would it take to fill an average man's lungs, total capacity of which is about 4.5 liters? Assume 1.00 atm pressure and 37.0°C.
1. 1.24 mol
2. 0.75 mol
3. 11.2 mol
4. 0.18 mole
5. 37.0 mol
A 268 cm³ sample of an ideal gas at 18°C and 748 Torr pressure is placed in an evacuated container of volume 648cm³. To what centigrade temperature must the assembly be heated so that the gas will fill the whole chamber at 748 Torr?
1. 704°C
2. 431°C
3. 597°C
4. 324°C
5. 120°C
A bomb calorimeter has a heat capacity of 3.18 kJ/K. When 0.0038 mol of a gas is burned in the calorimeter, the temperature increased from 25.0°C to 27.3°C. Calculate the energy released by the combustion of one mole of the gas.
1. 7.3 kJ
2. -1.9 x 10³ kJ
3. 2.8 x 10^-2 kJ
4. -2.8 x 10^-2 kJ
5. -3.6 x 10² kJ
The specific heat of iron is 0.450 J/(g·°C). How much heat is required to raise the temperature of a 5.00 gram sample of iron from 22°C to 53°C?
1. 69.8 J
2. 155 J
3. -43 J
4. 344 J
5. 18 J
A gas absorbs 2.5 J of heat and then performs 13.1 J of work. The change in internal energy of the gas is:
1. 5.2 J
2. -15.6 J
3. 15.6 J
4. 10.6 J
5. -10.6 J
As a result of an exothermic reaction,
1. the energy of the sytem and the energy of the surroundings are increased.
2. the energy of the system is increased and the energy of the surroundings are decreased.
3. the energy of the system is decreased and the energy of the surroundings are increased.
4. the energy of the system and the energy of the surroundings are decreased.
5. None of these are accurate
Calculate the work done for the expansion of oxygen gas from 2.5 liters to 3.7 liters against a pressure of 720 torr.
1. -1.14 liter·atm
2. 864 liter·atm
3. -864 liter·atm
4. 8.79 liter·atm
5. -4.78 liter·atm
For a particular process, q = -117 kJ and w = 73 kJ. How many of the following statements are true?
- Work is done on the system
- Heat is released to the surroundings
- The change in internal energy is 44 kj
- This energy change could occur as a liquid vaporizes
- The change can only occur at constant pressure
1. Only one statement is true.
2. Two of the statements are true.
3. Three of the statements are true.
4. Four of the statements are true.
5. All five of the statements are true.
The specific heat of liquid water is 4.18 J/°C·g and the specific heat of carbon is 0.71 J/°C·g. A 10 gram sample of water and a 10 gram sample of carbon are each subjected to 155 J of heat. If both samples started at 25°C, which substance will have the higher final temperature, and by what magnitude?
1. water, by 3.47°C
2. water, by 28.7°C
3. carbon, by 18.1°C
4. carbon, by 215°C
5. Neither. They will have the same final temperature because the started at the same temperature and were exposed to the same quantity of heat.
A 47.5 gram sample of a metal at a temperature of 425°C is placed in 1.00 liters (1000 grams) of water which had an initial temperature of 18°C. What is the specific heat capacity of the metal if the final temperature of the metal and water at equilibrium is 21°C? (The specific heat capacity of water is 4.18 J/°C·g.
1. 0.65 J/°C·g
2. 12.54 J/°C·g
3. 0.03 J/°C·g
4. 1.47 J/°C·g
5. -0.75 J/°C·g
20.0 mL of pure water at 285 K is mixed with 48 mL of water at 315 K. What is the final temperature of the mixture in kelvins?
1. 275 K
2. 318 K
3. 290 K
4. 306 K
5. None of these
Calculate the work associated with the compression of a gas from 86 liters to 48 liters at a constant pressure of 2.0 atm.
1. -76 L·atm
2. 76 L·atm
3. 268 L·atm
4. 13.5 L·atm
5. 0.050 L·atm
Which of the following fuel sources is not renewable?
1. ethanol
2. methanol
3. seed oil
4. shale oil
5. hydrogen
Calculate the heat evolved in the formation of 1 mole of PbSO₄(s) from its elements, given the following:
- Pb(s) + S(s) → PbS(s) + 94 kJ/mol
- PbS(s) + 2O₂(g) → PbSO₄(s) + 824 kJ/mol
1. -918 kJ/mol
2. -730 kJ/mol
3. 730 kJ/mol
4. 918 kJ/mol
5. None of these
Consider the following numbered processes:

1) A → 2B + DH₁
2) B → C + D + DH₂
3) E → 2D + DH₃

DH for the process A → 2C + E is
1. DH₁ + DH₂ + DH₃
2. DH₁ - 2DH₃
3. DH₁ + 2DH₂ - DH₃
4. 2DH₁ + DH₂ - DH₃
5. 2DH₁ + 2DH₂ - DH₃
Given the following data:
- K(s) → K(g) + 90. kJ
- K(g) → K⁺(g) + e^- + 419 kJ
- F₂(g) → 2F(g) + 151 kJ
- F^-(g) → F(g) + e^- + 333 kJ
- KF(s) → K⁺(g) + F^-(g) + 803 kJ
Calculate DH for the reaction K(s) +1/2F₂(g) → KF(s)
1. 317 kJ
2. -401 kJ
3. -1721 kJ
4. -552 kJ
5. 1796 kJ
A sample of wood has a heat of combustion of 3.29 kJ/g. What quantity of the wood must be burned to heat 250. g of water from 18°C to 85°C? Once again, the specific heat capacity of water is 4.18 J/°C·g.
1. 0.45 g
2. 12.4 g
3. 85.1 g
4. 2.13 x 10⁴ g
5. 21.3 g