Quiz 5 Chemistry Gases

Consider three 1-L flasks at the same temperature and pressure. Flask A contains CO gas, flask B contains N2 gas, and flask C contains O2 gas. In which flask do the molecules have the greatest kinetic energy? flask C The molecules in all the flasks have the same kinetic energy. flask A The molecules in two of the flasks have the same kinetic energy. flask B

The molecules in all the flasks have the same kinetic energy.

How is the observed pressure of a gas related to the ideal pressure? They are equal. The observed pressure is less than the ideal pressure. none of these The observed pressure is greater than the ideal pressure. The relationship depends on the gas.

The observed pressure is less than the ideal pressure.

The number of wall impacts per second versus the square root of Kelvin temperature for 1 mol of an ideal gas at constant volume Which graph represents the plot?

m=1

The pressure of an ideal gas versus the number of moles at constant temperature and volume Which graph represents the plot?

m=1

Calculate the temperature at which the average kinetic energy of O2 gas is twice that of He gas at 10.0°C. 293°C 10.0°C 160.0°C 20.0°C 2.50°C

293°C

Calculate the following ratios for a gas at Kelvin temperatures T1 and T2 where T2 = 2T1. Mean free path at T1 : Mean free path at T2 0.50 1.4 2.0 0.71 1.0

0.50

Calculate the following ratios for a gas at Kelvin temperatures T1 and T2 where T2 = 2T1. Average kinetic energy at T1 : Average kinetic energy at T2 1.0 1.4 0.71 0.50 2.0

0.50

Samples of the gases H2(g) and SO2(g) have equal masses and are at the same temperature and pressure. Calculate the following: The ratio of average kinetic energies per molecule (H2:SO2) 1.0 0.18 32 5.6 180

1.0

Consider separate samples of Ar(g) and Ne(g). For what ratio of absolute temperatures (Ne:Ar) are the average kinetic energies equal? 0.505 1.00 1.41 1.98 none of these

1.00

The valve between a 3.60-L tank containing O2(g) at 7.56 atm and a 3.40-L tank containing Ne(g) at 5.92 atm is opened. Calculate the ratio of partial pressures (O2:Ne) in the container. 1.35 0.561 0.740 1.28 1.06

1.35

A plastic bag is weighed and then filled successively with two gases, X and Y. The following data are gathered: Temperature: 0.0°C Pressure: 1.00 atm Mass of empty bag: 20.77 g Mass of bag filled with gas X: 24.97 g Mass of 1.12 L of air at conditions given: 1.30 g Volume of bag: 1.12 L Molar volume at STP: 22.4 L The molar mass of gas Y is 56.0 g/mol. 157 g/mol. 125 g/mol. 140. g/mol. 89.0 g/mol.

125 g/mol.

Consider two samples of helium in separate containers of the same volume. Sample 1 has an absolute temperature four times that of Sample 2. Both samples are at the same pressure. Calculate the ratio Z1/Z2. 1:2 4:1 1:1 1:4 2:1

1:2

Consider two samples of helium in separate containers of the same volume. Sample 1 has an absolute temperature four times that of Sample 2. Both samples are at the same pressure. Calculate the ratio n1/n2. 2:1 1:2 1:1 4:1 1:4

1:4

Calculate the ratio of the change in momentum per wall impact for Ar(g) to that for He(g) if the gases are at the same temperature and pressure. 0.100 3.16 9.98 0.316 none of these

3.16

Samples of the gases H2(g) and SO2(g) have equal masses and are at the same temperature and pressure. Calculate the following: The ratio of volumes mc005-1.jpg. 5.6 32 0.18 1.0 180

32

Samples of the gases H2(g) and SO2(g) have equal masses and are at the same temperature and pressure. Calculate the following: The ratio of rates of impact with the walls (H2:SO2) per unit area 5.6 180 0.18 32 1.0

5.6

The root-mean-square velocity of CO gas at 15°C is 116 m/s. 16.0 m/s 507 m/s. 3.66 m/s 50.3 m/s.

507 m/s.

A 259.6-L cylinder contains 63.5% He(g) and 36.5% Kr(g) by mass at 22.0°C and 1.25 atm total pressure. What is the mass of He in this container? 34.1 g 30.0 g 52.2 g 700 g 82.2 g

52.2 g

A cylinder of oxygen gas contains 26.4 g of O2. Another cylinder, twice the volume of the cylinder containing oxygen (and at the same conditions of pressure and temperature), contains CO2 gas. Assuming ideal behavior, what is the mass of the carbon dioxide? 36.3 g 13.2 g none of these 52.8 g 72.6 g

72.6 g

Four identical 1.0-L flasks contain the gases He, Cl2, CH4, and NH3, each at 0°C and 1 atm pressure. Which gas sample has the greatest number of molecules? Cl2 NH3 He All the gases have the same number of molecules. CH4

All the gases have the same number of molecules.

Near sea level, the atmosphere is composed of 78% nitrogen and 20% oxygen. Other trace gases make up the remaining 2%. At room temperature, all the gas molecules move at the same speed. B and D B, D, and E the nitrogen gas molecules, on average, move slower than the oxygen molecules. some nitrogen gas molecules could move faster than some of the oxygen gas molecules. the nitrogen gas molecules, on average, move faster than the oxygen molecules. some nitrogen gas molecules could move slower than some of the oxygen molecules. C and D

B, D, and E

The root-mean-square velocity of a gas in a closed container of fixed volume is increased from 345 m/s to 690 m/s. Which one of the following statements might explain correctly how this change was accomplished? By pumping in more gas at constant temperature, the pressure was quadrupled. None of these statements correctly explains the change. By pumping out 75% of the gas at constant temperature, the pressure was decreased to 25% of its original value. By heating the gas, the pressure was quadrupled. By heating the gas, the temperature was doubled.

By heating the gas, the pressure was quadrupled.

Order the following according to increasing rate of effusion: F2, Cl2, NO, NO2, CH4 Cl2 < F2 < NO2 < CH4 < NO F2 < NO < Cl2 < NO2 < CH4 CH4 < NO2 < NO < F2 < Cl2 Cl2 < NO2 < F2 < NO < CH4 CH4 < NO < F2 < NO2 < Cl2

Cl2 < NO2 < F2 < NO < CH4

Four identical 1.0-L flasks contain the gases He, Cl2, CH4, and NH3, each at 0°C and 1 atm pressure. For which gas are the collisions elastic? Cl2 NH3 CH4 The collisions are elastic for all the gases. He

The collisions are elastic for all the gases.

Consider three 1.0-L flasks at STP. Flask A contains N2 gas, flask B contains Kr gas, and flask C contains He gas. In which flask do the gas particles have the lowest average kinetic energy? flask C The gas particles in all of the flasks have the same average kinetic energy. flask A The gas particles in two of the flasks have the same average kinetic energy. flask B

The gas particles in all of the flasks have the same average kinetic energy.

Consider the following gas samples: Sample A Sample B S2(g) O2(g) n = 1 mol n = 2 mol T = 800 K T = 400 K P = 0.20 atm P = 0.40 atm Which one of the following statements is false? The fraction of molecules in sample A having a kinetic energies greater than some high fixed value is larger than the fraction of molecules in sample B having kinetic energies greater than that same high fixed value. The average kinetic energy of the molecules in sample A is twice the average kinetic energy of the molecules in sample B. Assuming identical intermolecular forces in the two samples, sample A should be more nearly ideal than sample B. The root-mean-square velocity of molecules in sample A is twice as large as the root-mean-square velocity of molecules in sample B. The volume of sample A is twice the volume of sample B.

The root-mean-square velocity of molecules in sample A is twice as large as the root-mean-square velocity of molecules in sample B.

Consider three 1-L flasks at the same temperature and pressure. Flask A contains CO gas, flask B contains N2 gas, and flask C contains O2 gas. Which contains the lowest density? All are the same. flask A flask C flask B Two of the flasks contain gases at the same density.

Two of the flasks contain gases at the same density.

Consider three 1.0-L flasks at STP. Flask A contains Ar gas, flask B contains Kr gas, and flask C contains H2 gas. In which flask do the gas particles have the highest average velocity? flask A The gas particles in all the flasks have the same average velocity. flask C flask B The gas particles in two of the flasks have the same average velocity.

flask C

The pressure of an ideal gas versus the volume at constant temperature and number of moles Which graph represents the plot?

none of these

The kinetic-molecular theory of gases does not assume that gas particles are very small compared to the average distance between the particles. the average velocity of gas particles is directly proportional to the absolute temperature. gas particles collide with the walls of their container in elastic collisions. All of these are correct. gases are made up of tiny particles in constant chaotic motion.

the average velocity of gas particles is directly proportional to the absolute temperature.