Gases (MC) Flashcards
Which increases when a gas is heated at constant volume?
I. Pressure
II. Kinetic energy of molecules
III. Attractive forces between molecules
a. I only
b. II and III only
c. I and II only
d. II only
C
A gas is most likely to behave as an ideal gas in which instance?
a. At high pressures, because the distance between molecules is likely to be small in relation to the size of the molecules.
b. When the molecule is highly polar, because intermolecular forces are more likely.
c. At room temperature and pressure, because intermolecular interactions are minimized and the particles are relatively apart.
d. At low temperature, because the particles have insufficient kinetic energy to overcome intermolecular attractions.
C
Which statement is true of a measured pressure of a sample of hydrogen gas collected over water at constant temperature?
a. The measured pressure is equal to the pressure of dry hydrogen.
b. The measured pressure is not related to the pressure of dry hydrogen.
c. The measured pressure is less than the pressure of dry hydrogen.
d. The measured pressure is greater than the pressure of dry hydrogen.
D
Consider three one-liter flasks lettered A, B, and C, filled with the gases NO, NO2, and N2O respectively, each at STP. Which flask contains the fewest molecules?
a. Flask C
b. They all contain the same number of molecules.
c. Flask B
d. Flask A
B
If the volume of a gas within a closed container is doubled at constant temperature, then
a. the pressure of the gas increases to four times its original value.
b. the pressure of the gas decreases to 1/2 its original value.
c. the pressure of the gas increases to twice its value.
d. the pressure of the gas remains the same.
B
Three 1.00-L flasks at 25ºC and 725 torr contain the gases CH4 (flask A), CO2 (flask B), and C2H6 (flask C). In which flask(s) is/are there 0.039 mol of gas?
a. flask C
b. flasks A and B
c. flasks B and C
d. flasks A, B and C
D
Why could the pressure of a sample of gas at a constant volume fall 75 mm Hg?
a. The temperature increased.
b. The temperature decreased.
c. The volume increased.
d. The container exploded.
B
If gas A has a molar mass greater than that of gas B and samples of each gas at identical temperatures and pressures contain equal numbers of molecules, then
a. the volume of gas B is greater than that of gas A
b. the volume of gas A is greater than that of gas B
c. the volume of gas A and gas B are equal
d. their volumes are proportional to their molar masses
C
If the height of mercury in a barometer at 0ºC is less than 760 mm Hg, then
a. the atmospheric pressure is equal to standard atmospheric pressure.
b. the atmospheric pressure is less than standard atmospheric pressure.
c. the atmospheric pressure cannot be determined.
d. the atmospheric pressure is greater than standard atmospheric pressure.
B
If force is held constant as surface area decreases, pressure
a. increases.
b. increases or decreases, depending on the volume change.
c. decreases.
d. remains constant.
A
To correct for the partial pressure of water vapor in a gas collection bottle, the vapor pressure of H2O at the collecting temperature is generally
a. added to the atmospheric pressure.
b. added to the pressure of the collected gas.
c. subtracted from the partial pressure of the collected gas.
d. subtracted form the atmospheric pressure.
D
If the temperature of a fixed quantity of gas decreases and the pressure remains unchanged,
a. its volume increases.
b. its volume is unchanged.
c. its volume decreases.
d. its density decreases.
C
