Deck 9: The Gaseous State

Question 1

Sodium bicarbonate, NaHCO₃, reacts with HCl to form what gases?

A) H₂
B) CO
C) CO₂
D) NaCl
E) it does not react

Answer 1

C

Question 2

Hydrogen peroxide, H₂O₂, decomposes into water and oxygen gas. How many moles of oxygen gas are formed from the decomposition of 1 mole of hydrogen peroxide?

A) 0
B) 0.5
C) 1
D) 1.5
E) 2

Answer 2

B

Question 3

10 L of a gas at constant pressure is initially at 25°C. If the temperature is increased to 50°C the volume of the gas will

A) increase by about 8%.
B) decrease by about 8%.
C) increase by 100%.
D) decrease by 100%.
E) stay the same.

Answer 3

A

Question 4

Which of the following is not equal to 1 atm?

A) 760 Torr
B) 760 mm Hg (at 0°C)
C) 14.7 psi
D) 1 bar
E) 10⁵ Pa
F) a & b
G) d & e

Question 5

Ethanol has a density of 0.789 g cm^-3. What is the pressure at the bottom of a 125 cm tall column of ethanol?

A) 9.66×10² Pa
B) 9.66×10³ Pa
C) 9.66×10⁴ Pa
D) 9.66×10⁵ Pa
E) 9.66×10⁸ Pa

Question 6

A gas has a temperature of 34.9°C and a volume of 2.8L. It is cooled at constant pressure and the new volume is 2.5 L. What is the new temperature of the gas?

A) 1.89°C
B) 11.6°C
C) 25.2°C
D) 31.2°C
E) 39.1°C

Question 7

Sodium metal reacts with water form hydrogen gas by the following unbalanced chemical equation
Na(s) + H₂O(l) → NaOH(aq) + H₂(g)
If 20 g of sodium are reacted with excess water at a temperature of 30°C and a pressure of 0.8 atm, what volume of H₂ is produced?

A) 1.34 L
B) 13.5 L
C) 21.6 L
D) 26.7 L
E) 27.0

Question 8

A cylinder of compressed He originally has a pressure of 20 atm and a volume 10 L at a temperature of 25°C. It is used to fill 10, 1 L balloons at a pressure of 0.99 atm at 25°C. After filling the balloons what is the pressure in the tank?

A) 12.0 atm
B) 17.2 atm
C) 18.0 atm
D) 19.0 atm
E) 19.8 atm

Question 9

A balloon has a volume of 1.2 L at a pressure of 0.98 atm and a temperature of 25°C. It rises in the atmosphere to a point where the pressure of 0.28 atm and a temperature of -33°C. What is the volume of the balloon?

A) 0.42 L
B) 3.8 L
C) 5.6 L
D) 7.1 L
E) There is no way to know.

Question 10

At a temperature of 48.2°C a gas has volume of 6.8 gallons at a pressure of 282 psi. If the gas is compressed at constant temperature to a volume of 3 gallons, what is the pressure?

A) 124 psi
B) 226 psi
C) 308 psi
D) 639 psi
E) 785 psi

Question 11

12.2 g of I₂(s) is placed in an evacuated 15 L container and heated to 100°C. At this temperature all of the solid sublimes into vapor. What is the pressure in the container?

A) 2.65×10³ Pa
B) 9.93×10³ Pa
C) 1.82×10⁴ Pa
D) 4.97×10⁴ Pa
E) 8.23×10⁵ Pa

Question 12

At a fixed temperature and pressure 4.5 L of F₂(g) and 1.5 L of Cl₂(g) react completely to from 3.0 L of a new gas. What is the formula of the new gas?

A) ClF
B) Cl₂F₂
C) ClF₃
D) Cl₂F₆
E) Cl₃F

Question 13

Ammonia can be formed from the reaction of hydrogen and nitrogen gas by the following reaction
N₂(g) + 3H₂(g) → 2NH₃(g)
At 127°C an equilibrium mixture is found to have a partial pressure of 103 kPa for NH₃, a partial pressure of 2030 kPa for N₂, and a partial pressure of 10 kPa for H₂. If the volume of the container is 10 L, how many moles of NH₃ are there?

A) 0.31
B) 0.52
C) 0.98
D) 6.4
E) 20.0

Question 14

Ammonia can be formed from the reaction of hydrogen and nitrogen gas by the following reaction
N₂(g) + 3H₂(g) → 2NH₃(g)
At 127°C an equilibrium mixture is found to have a partial pressure of 103 kPa for NH₃, a partial pressure of 2030 kPa for N₂, and a partial pressure of 10 kPa for H₂. What is the total pressure in the container?

A) 1.03 bar
B) 1.34 bar
C) 15.4 bar
D) 21.43 bar
E) it depends on the number of moles of gas

Question 15

In the gas shift reaction carbon monoxide reacts with steam to from hydrogen gas and carbon dioxide
CO(g) + H₂O(g) → H₂(g) + CO₂(g)
If a 10 L container initially has a partial pressure of 0.25 atm of CO and 1.35 atm of H₂O at constant temperature of 1000 K. When the partial pressure of CO has dropped to 0.15 atm, what is the total pressure in the container?

A) 0.10 atm
B) 0.15 atm
C) 1.40 atm
D) 1.60 atm
E) 1.75 atm

Question 16

If air has a concentration of CO₂ of 380 ppm, what is the partial pressure of CO₂ if the total pressure of 0.99 atm?

A) 3.76×10^-4 atm
B) 3.84×10^-4 atm
C) 3.84×10^-3 atm
D) 3.76×10^-1 atm
E) 3.84×10^-1 atm

Question 17

At room temperature which of the following gases will have the fastest average velocity?

A) H₂
B) He
C) N₂
D) O₂
E) it depends on the pressure and volume

Question 18

From the kinetic theory of gases which do you predict is the fastest?

A) the most probable velocity of the gas.
B) the root mean square velocity of the gas.
C) the average velocity of the gas.
D) they will all be the same.
E) it depends on the molecular mass of the gas.

Question 19

Comparing the rms velocities H₂ and He.

A) He is 2 times faster than H₂
B) He is 2 times slower than H₂
C) He is 4 times faster than H₂
D) He is 4 times slower than H₂
E) none of the above

Question 20

What is the rms velocity of N₂ gas at 100°C?

A) 18 m s^-1
B) 36 m s^-1
C) 156 m s¹
D) 298 m s^-1
E) 576 m s^-1

Question 21

The vibrational frequency of carbon monoxide is 6.42×10¹³ s^-1. At 25°C what is the relative population of the first excited vibrational state compared to the ground state?

A) 3.2×10^-5
B) 4.5×10^-3
C) 0.62
D) 1.0
E) none of the above

Question 22

The vibration frequency of HCl is 8.66×10¹³ s^-1 and HBr is 7.68×10¹³ s^-1. At 1000 K which molecules will have a larger population in the first excited vibrational state?

A) HCl
B) HBr
C) they will be exactly equal
D) it depends on the force constant of the bond
E) it depends on the total pressure

Question 23

Comparing the van der Waals b constant for Xe with that of Ne

A) Xe will be larger
B) Ne will be larger
C) they will be exactly the same
D) either Xe or Ne will be larger depending on the temperature
E) either Xe or Ne will be larger depending on the pressure

Question 24

At the same temperature and pressure, comparing one mole of a gas that is described the following equation of state
P(V - nb) = nRT where b > 0
To one mole of an ideal gas

A) the volume will be larger than that of the ideal gas
B) the volume will be smaller than that of the ideal gas
C) the volume will be the same as that of the ideal gas
D) the volume will be larger or smaller depending on the temperature
E) the volume will be larger or smaller depending on the pressure

Question 25

Which of the following in gases is least likely to behave ideally?

A) He
B) Ne
C) N₂
D) H₂
E) NH₃

Question 26

If the compressibility factor for a real gas yields a z < 1, then volume of that gas compared to the volume of an ideal gas at the same temperature and pressure would be

A) smaller volume than the ideal gas.
B) larger volume than the ideal gas.
C) identical volume to the ideal gas.
D) depend on the molecular weight of the gas.
E) depend on the temperature.

Question 27

Helium effuses through a small opening at a rate of 1×10^-9 mol s^-1. An unknown gas at the same temperature and pressure is found to effuse through the same opening at a rate of 3.78×10^-10 mol s^-1. What is the molecular mass of the unknown gas?

A) 4 g mol^-1
B) 14 g mol^-1
C) 18 g mol^-1
D) 28 g mol^-1
E) 40 g mol^-1

Question 28

Air is 78.1% N₂ gas. This is the

A) percent by volume.
B) percent by mole.
C) percent by mass.
D) a & b
E) a & c

Question 29

Which has more average kinetic energy per molecule, N₂ gas at 25°C or He gas at 25°C?

A) N₂
B) He
C) they are the same
D) it depends on the pressure
E) it depends on the volume

Question 30

A 5 L container is held at a constant temperature. Initially it has a partial pressure of 1.2 bar N₂ and a partial pressure of 0.3 bars H₂. The nitrogen and hydrogen react to form some NH₃ and the total pressure is found to be 1.425 bar. What is the partial pressure of NH₃?

A) 0.075 bar
B) 0.55 bar
C) 0.63 bar
D) 0.76 bar
E) 1.38 bar

Question 31

Based on the van der Waals equation of state Which of the following molecules - hydrogen chloride, nitrogen dioxide, or sulfur dioxide - should behave most like an ideal gas.

A) HCl
B) NO₂
C) SO₂
D) Must know n to answer this question
E) Must know P and V to answer this question

Question 32

The compressibility factor (z) for an ideal gas is

A)

B) 0
C) 1
D) R
E) k_B

Question 33

With respect to the Maxwell-Boltzmann probability distribution function of molecular speeds, which of the following is true?

A)

B)

C)

D)

E) A and D