Deck 13: Gas Mixtures

Question 1

An ideal gas mixture whose apparent molar mass is 48 kg/kmol consists of nitrogen N₂ and three other gases. If the mole fraction of nitrogen is 0.24, its mass fraction is

A)0.24
B)0.14
C)0.41
D)0.86
E)0.70

Answer 1

0.14

Question 2

An ideal gas mixture consists of 3 kmol of N₂ and 7 kmol of CO₂. The mass fraction of CO₂ in the mixture is

A)0.214
B)0.700
C)0.500
D)0.652
E)0.786

Answer 2

0.786

Question 3

An ideal gas mixture consists of 4 kmol of N₂ and 6 kmol of CO₂. The apparent gas constant of the mixture is

A)0.221 kJ/kg.K
B)0.232 kJ/kg.K
C)0.243 kJ/kg.K
D)0.475 kJ/kg.K
E)1.12 kJ/kg.K

Answer 3

0.221 kJ/kg.K

Question 4

A rigid tank is divided into two compartments by a partition. One compartment contains 2 kmol of N₂ at 500 kPa pressure and the other compartment contains 8 kmol of CO₂ at 200 kPa. Now the partition is removed, and the two gases form a homogeneous mixture at 300 kPa. The partial pressure of N₂ in the mixture is

A)41 kPa
B)60 kPa
C)150 kPa
D)115 kPa
E)225 kPa

Question 5

A 100-L rigid tank contains an ideal gas mixture of 5 g of O₂ and 5 g of CO₂ at a specified pressure and temperature. If O₂ were separated from the mixture and stored at mixture temperature and pressure, its volume would be

A)35 L
B)39 L
C)50 L
D)58 L
E)100 L

Question 6

An ideal gas mixture consists of 4 kg of Ar and 6 kg of CO₂ gases. The mixture is now heated at constant volume from 275 K to 325 K. The amount of heat transfer is

A)485 kJ
B)716 kJ
C)519 kJ
D)834 kJ
E)1687 kJ

Question 7

An ideal gas mixture consists of 35% helium and 65% argon gases by mass. The mixture is now expanded isentropically in a turbine from 400°C and 1.2 MPa to a pressure of 150 kPa. The mixture temperature at turbine exit is

A)174°C
B)20°C
C)99°C
D)148°C
E)256°C

Question 8

One compartment of an insulated rigid tank contains 3 kmol of CO₂ at 20°C and 140 kPa while the other compartment contains 5 kmol of H₂ gas at 35°C and 280 kPa. Now the partition between the two gases is removed, and the two gases form a homogeneous ideal gas mixture. The temperature of the mixture is

A)25°C
B)28°C
C)22°C
D)32°C
E)34°C

Question 9

A piston-cylinder device contains an ideal gas mixture of 3 kmol of He gas and 7 kmol of Ar gas at 35°C and 420 kPa. Now the gas expands at constant pressure until its volume doubles. The amount of heat transfer to the gas mixture is

A)5.9 MJ
B)7.3 MJ
C)38 MJ
D)257 MJ
E)64 MJ

Question 10

An ideal gas mixture of helium and argon gases with identical mass fractions enters a turbine at 1500 K and 1 MPa at a rate of 0.25 kg/s, and expands isentropically to 200 kPa. The power output of the turbine is

A)366 kW
B)474 kW
C)570 kW
D)743 kW
E)1630 kW