rest of the ap chem ms buck questions

21. Two flexible containers for gases are at the same temperature and pressure. One holds 0.50 gram of hydrogen and the other holds 8.0 grams of oxygen. Which of the following statements regarding these gas samples is FALSE?

e). The average speed of the hydrogen molecules is the same as the average speed of the oxygen molecules.

94. H2(g) + 1/2 O2(g) H2O(l) H° = - 286 kJ 2 Na(s) + 1/2 O2(g) Na2O(s) H° = - 414 kJ Na(s) + 1/2 O2(g) + 1/2 H2(g) NaOH(s) H° = - 425 kJ Based on the information above, what is the standard enthalpy change for the following reaction? Na2O(s) + H2O(l) 2 NaOH(s)

D). -150 KJ

When the actual gas volume is greater then the volume predicted by the ideal gas law, the explanation lies in the fact that the ideal gas law does NOT include a factor for molecular.

a). volume

A sample of 9.00 grams of aluminum metal is added to an excess of hydrochloric acid. The volume of hydrogen gas produced at standard temperature and pressure is

b). 11.2 liters

Hydrogen gas is collected over water at 24 °C. The total pressure of the sample is 755 millimeters of mercury. At 24 °C, the vapor pressure of water is 22 millimeters of mercury. What is the partial pressure of the hydrogen gas?

b). 733 mm Hg

97. For which of the following processes would S have a negative value? I. 2 Fe2O3(s) 4 Fe(s) + 3 O2(g) II. Mg2+ + 2 OH ̄ Mg(OH)2(s) III. H2(g) + C2H4(g) 3 C2H6(g)

b). I and II only

When a sample of oxygen gas in a closed container of constant volume is heated until its absolute temperature is doubled, which of the following is also doubled?

b). the pressure of the gas

A sample of 0.0100 mole of oxygen gas is confined at 37° C and 0.216 atmosphere. What would be the pressure of this sample at 15° C and the same volume?

c). 0.201 atm

A gaseous mixture containing 7.0 moles of nitrogen, 2.5 moles of oxygen, and 0.50 mole of helium exerts a total pressure of 0.90 atmosphere. What is the partial pressure of the nitrogen?

c). 0.63 atm

19. The system shown above is at equilibrium at 28 °C. At this temperature, the vapor pressure of water is 28 millimeters of mercury. The partial pressure of O2(g) in the system is

c). 133 mmHg

20. A hydrocarbon gas with an empirical formula CH2 has a density of 1.88 grams per liter at 0 °C and 1.00 atmosphere. A possible formula for the hydrocarbon is

c). C3H6

A sample of an ideal gas is cooled from 50.0 °C to 25.0 °C in a sealed container of constant volume. Which of the following values for the gas will decrease? I. The average molecular mass of the gas II. The average distance between the molecules III. The average speed of the molecules

c). III only

95. A cube of ice is added to some hot water in a rigid, insulated container, which is then sealed. There is no heat exchange with the surroundings. What has happened to the total energy and the total entropy when the system reaches equilibrium?

c. Energy: constant, Entropy: increases

A compound is heated to produce a gas whose molecular weight is to be determined. The gas is collected by displacing water in a water-filled flask inverted in a trough of water. Which of the following is necessary to calculate the molecular weight of the gas, but does NOT need to be measured during the experiment?

c. Vapor pressure of the water

Samples of F2 gas and Xe gas are mixed in a container of fixed volume. The initial partial pressure of the F2 gas is 8.0 atmospheres and that of the Xe gas is 1.7 atmospheres. When all of the Xe gas reacted, forming a solid compound, the pressure of the unreacted F2 gas was 4.6 atmospheres. The temperature remained constant. What is the formula of the compound?

c. XeF4

96. CuO(s) + H2(g)Cu(s) + H2O(g); H = - 2.0 kilojoules When the substances in the equation above are at equilibrium at pressure P and temperature T, the equilibrium can be shifted to favor the products by

c. decreasing the temperature

98. CH4(g) + 2 O2(g) CO2(g) + 2 H2O(l); H = - 889.1 kJ Hf° H2O(l) = - 285.8 kJ / mole Hf° CO2(g) = - 393.3 kJ / mole What is the standard heat of formation of methane, Hf° CH4(g), as calculated from the data above?

d) 75.8 kJ/mole

2 K + 2 H2O 2 K+ + 2 OH ̄ + H2 When 0.400 mole of potassium reacts with excess water at standard temperature and pressure as shown in the equation above, the volume of hydrogen gas produced is

d). 4.48 liters

A sample of 3.30 grams of an ideal gas at 150.0 °C and 1.25 atmospheres pressure has a volume of 2.00 liters. What is the molar mass of the gas? The gas constant, R, is 0.0821 L atm mol ̄1

d). 45.8 grams/mole

99. At 25°C, a sample of NH3 (molar mass 17 grams) effuses at the rate of 0.050 mole per minute. Under the same conditions, which of the following gases effuses at approximately one-half that rate?

d). Cl2 (molar mass 71 grams)