Ideal GasesContributions by:

John L. Falconer & Will MedlinDepartment of Chemical and Biological Engineering

University of ColoradoBoulder, CO 80309-0424

Supported by the National Science Foundation

A rigid tank contains CO2 at 2 atm and 50°C. When

the tank is heated to 250°C, the pressure increases significantly and the gas density ____________.

A. increases

B. decreases

C. remains the sameGas

The pressure of an ideal gas in a fixed volume container is doubled without changing the number of moles of the gas. The average velocity of the particles should __________.

A. not change

B. be doubled

C. be halved

D. be quadrupled

E. none of the above

An ideal gas (water) enters a compressor, and the exiting water is a real fluid. The shaft work will be ____________ that obtained if the exiting water could be considered an ideal gas.

A. higher than

B. lower than

C. the same as

1 mol CH4 (1 bar, 50°C) is mixed with 1 mol O2 (1 bar,

50°C) to form a mixture at 2 bar and 50°C. Assume ideal gases. The Gibbs free energy change is _____________.

A. positive

B. negative

C. zero

D. Need more information

Which system has the highest internal energy if one mole of the same ideal gas is in each piston-cylinder?

A. A

B. B

C. Both have the same internal energy

2 atm

50°C

10 atm50°C

A B

A constant-volume tank contains CO2 at 2 atm.

Nitrogen is injected into the tank. If the CO2 all remains

in the tank, its partial pressure ____________. Assume ideal gases and an isothermal system.

A. decreases

B. increases

C. stays the same

CO2

N2

A constant-volume tanks contains 4 mol CO2 and 1 mol

N2 at a total pressure of 2 atm. The N2 is removed

completely through a membrane that allows only N2 to

permeate. If all the CO2 remains in the tank, the partial

pressure of CO2 ___________.

Assume ideal gases and an isothermal system.

A. decreases

B. increases

C. stays the same CO2 + N2

membrane N2

An ideal gas is at 1 atm in a piston-cylinder. The piston is weightless and frictionless. When the mass is removed from the piston, the gas temperature ____________.

A. increases

B. decreases

C. remains the same1 kg

Vacuum

Gas

Piston

Weight

Stopper

1 mol CO2 and 2 mol N2 are heated at constant

pressure. The partial pressure of the CO2 _________.

Assume ideal gases.

A. increases

B. decreases

C. stays the same

Start

1 kg

1 mol CO2

2 mol N2

1 mol CO2

2 mol N2

After heating

1 kg

CO2

N2

1 mol CO2 and 2 mol N2 are in a container at 100°C.

The container is then placed in an ice bath at constant pressure. The partial pressure of the CO2 _________.

Assume ideal gases.

A. increases

B. decreases

C. stays the same

1 kg

Gas

Piston

Weight

1 kg

Gas

Start After cooling

A fixed volume tank has water in VLE. A mole of air was added to the system. All gases are ideal. The amount of liquid water ___________.

A. increases

B. decreases

C. stays the same

Vapor

Liquid

1 mol air

A fixed-volume tank contains CO2 and N2, both of

which are ideal gases. One mole of O2, also an ideal

gas, is added. The partial pressure of H2 __________.

A. increases

B. decreases

C. stays the same

PCO2 = 0.6 atm

PN2 = 0.5 atm

1 mol O2

A gas is heated and expands in a sealed, frictionless, piston-and cylinder arrangement, where the piston mass and the atmospheric pressure above the piston remain constant. The pressure of the gas will _________.

A. increase  

B. remain the same  

C. decrease  

D. Insufficient information  

Start

1 kg

Gas 1 mol CO2

2 mol N2

After heating

1 kg

Gas

Volume

B

Pre

ssu

re

E A

C

D

Which line corresponds to an isotherm?

A B C

D E

Which is the correct plot of enthalpy vs. mole fraction of one component for a binary mixture of ideal gases?

yi

H

yi

H

yi

H

yi

H

yi

H

A B C

D E

Which is the correct plot of Gibbs free energy vs. yi for

a binary mixture of ideal gases?

yi

G

yi

G

yi

G

yi

G

yi

G

A membrane divides a rigid, well-insulated 2 m3 tank into equal parts. The left side contains an ideal gas (Cp = 30 J/mol K) at 300 K and 10 bar and the right

side is a vacuum. If the membrane ruptures, what will be the final temperature of the gas?

A. 200 K

B. 300 K

C. 400 K

D. Need more information

Gas Vacuum

Membrane

A rigid isolated vessel is divided by a barrier into two chambers of equal volume. One side contains an idealmonatomic gas, the other side contains vacuum. If the barrier is removed, the temperature of the gas will __________.

A. double

B. be cut in half

C. not change

D. go to absolute zero

Ideal monotomic

gasVacuum

PistonRemoveStoppers

A rigid vessel is divided by a barrier into two chambers of equal volume. One side contains a real gas, the other side contains vacuum. If the barrier is removed, the temperature of the gas will _____________.

A. go to absolute zero

B. increase

C. decrease

D. not change

Real gas Vacuum

PistonRemoveStoppers