Chemistry Chapter 5

A sample of 35.1 grams of methane gas has a volume of 3.11 L at a pressure of 2.70 atm. Calculate the temperature.

46.8 K

Calculate the ratio of the effusion rates of N2 and N2O.

1.25

The partial pressures of CH4, N2, and O2 in a sample of gas were found to be 135 mmHg, 508 mmHg, and 571 mmHg respectively. Calculate the mole fraction of nitrogen.

0.418

The mass of 1.12 liters of gas Y at STP is found to be 6.23 g. The molar mass of gas Y is...

125 g/mol

What volume does 40.5 g of N2 occupy at STP?

32.4 L

All the following are postulates of the kinetic-molecular theory of gases except:

At a constant temperature, each molecule has the same kinetic energy.

When 0.72 g of a liquid is vaporized at 110*C and 0.967 atm, the gas occupies a volume of 0.559 L. The empirical formula of the gas is CH2. What is the molecular formula of the gas?

C3H6

For which gas do the molecules have the highest average velocity?

He

What would happen to the average kinetic energy of the molecules of a gas sample if the temperature of the sample increased from 20*C to 40*C?

It would increase

Graham's law states that

The rates of effusion of gases are inversely proportional to the square roots of their molar masses

For a gas, which two variables are directly proportional to each other if all other conditions remain constant?

V and n V and T

Gases generally have

low density

The standard temperature for gases is

0*C

A gas sample is heated from -20.0*C to 57.0*C and the volume is increased from 2.00 L to 4.50 L. If the initial pressure is 0.140 atm, what is the final pressure?

0.0811 atm

A glass column is filled with mercury inverted in a pool of mercury. The mercury column stabilizes at a height of 729 mm above the pool of mercury. What is the pressure of the atmosphere?

0.959 atm

Standard pressure for gases is

1 atm

Calculate the root mean square velocity for the O2 molecules in a sample of O2 gas at 11.8*C. (R=8.3145 J/K mol)

471.2 m/s

An excess of sodium hydroxide is treated with 26.5 L of dry hydrogen chloride gas measured at STP. What is the mass of sodium chloride formed?

69.1 g

Which of the following is true about the kinetic molecular theory?

Pressure is due to the collisions of the gas particles with the walls of the container.

You have a certain mass of helium gas (He) in a rigid steel container. You add the same mass of neon gas (Ne) to this container. Which of the following best describes what happens? Assume the temperature is constant.

The pressure in the container increases but does not double.

Dalton's law of partial pressures states that

The total pressure of a mixture of gases is the sum of the partial pressure of all the gaseous compounds.

Charles's law states that

The volume of a fixed amount of gas is directly proportional to its temperature in Kelvin at constant pressure

Boyle's law states that

The volume of a fixed amount of gas is inversely proportional to its pressure at constant temperature.

Consider a sample of gas in a container on a comfortable spring day. The Celsius temperature suddenly doubles, and you transfer the gas to a container with twice the volume of the first container. If the original pressure was 12 atm, what is a good estimate for the new pressure?

6.4 atm

Avogadro's law states that

Equal amounts of gases occupy the same volume at constant temperature and pressure.

Which gas sample has the greatest number of molecules?

all gases the same

For which gas are the molecules diatomic?

Cl2

Order the following in increasing rate of effusion:

Cl2<NO2<F2<NO<CH4

Use the kinetic molecular theory of gases to predict what would happen to a closed sample of a gas whose temperature increased while its volume decreased.

Its pressure would increase

A gas sample is held at constant pressure. The gas occupies 3.62 L of volume when the temperature is 21.6*C. Determine the temperature at which the volume of the gas is 3.42 L.

278 K

Which of the following would have a higher rate of effusion that C2H2?

CH4

Which of the following is not a postulate of the kinetic molecular theory?

Gas particles have most of their mass concentrated in the nucleus of the atom.