Deck 17: Thermodynamics and Gas Mixtures: Equations, Properties, and Applications

Question 1

For getting TdS equations, we assume entropy to be a function of T and V and also of T and p.

Answer 1

True

Question 2

During phase transitions like vaporization, melting and sublimation

A)pressure and temperature remains constant
B)volume and entropy changes
C)both of the mentioned
D)none of the mentioned

Answer 2

both of the mentioned

Question 3

Which of the following requirement is satisfied by a phase change of the first order?

A)there are changes of volume and entropy
B)the first-order derivative of the gibbs function changes discontinuously
C)both of the mentioned
D)none of the mentioned

Answer 3

both of the mentioned

Question 4

The vapour pressure p in kPa at

A)p = 101.325 exp (88/r)(1+t/tb)
B)p = 101.325 exp (88/r)(1+tb/t)
C)p = 101.325 exp (88/r)(1-t/tb)
D)p = 101.325 exp (88/r)(1-tb/t)

Question 5

The vapour pressure curve is of the form ln(p) = A + B/T + C*lnT + DT.

Question 6

According to Trouton's rule, the ratio of latent heat of vaporization to the boiling point at 1.013 bar is

A)77 kj/kgmol k
B)88 kj/kgmol k
C)99 kj/kgmol k
D)100 kj/kgmol k

Question 7

Estimate the freezing temperature of liquid water at a pressure of 30 MPa.

A)-2.2°c
B)0°c
C)-0.2°c
D)-1.2°c

Question 8

The expression nRT/V is called the partial pressure of a gas.

Question 9

The gas constant of the mixture is the   of the gas constants of the components.

A)average
B)weighted mean
C)sum
D)difference of the highest and the lowest

Question 10

A quantity called partial volume of a component of mixture is used.

Question 11

When gases which are at equal pressure and temperature are mixed adiabatically without work, then

A)internal energy of the gaseous system remains constant
B)heat transfer of the gaseous system remains constant
C)entropy of the gaseous system remains constant
D)all of the mentioned

Question 12

The fact that internal energy of a mixture is equal to the sum of the partial internal energies of the gases can also be applied to properties like H,Cv,Cp,S,F, and G.

Question 13

Which of the following statement is true?

A)the chart is plotted for pressure equal to 760mm hg
B)the constant wbt line represents adiabatic saturation process
C)the constant wbt line coincides with constant enthalpy line
D)all of the mentioned

Question 14

In sensible heating or cooling,

A)work done remains constant
B)dry bulb temperature or air remains constant
C)both of the mentioned
D)none of the mentioned

Question 15

Cooling and dehumidification of air is done in summer air conditioning.

Question 16

Heating and humidification is done in

A)summer air conditioning
B)winter air conditioning
C)both of the mentioned
D)none of the mentioned

Question 17

Which of the following is an absorbent?

A)silica gel
B)activated alumina
C)both of the mentioned
D)none of the mentioned

Question 18

When air passes through silica gel,

A)it absorbs water vapour molecules
B)latent heat of condensation is released
C)dbt of air increases
D)all of the mentioned

Question 19

In adiabatic evaporative cooling, heat transfer between chamber and surroundings is

A)zero
B)high
C)low
D)none of the mentioned

Question 20

The cooling tower uses the phenomenon of evaporative cooling to cool warm water above the dbt of air.

Question 21

Cooling towers are rated in terms of

A)approach
B)range
C)both of the mentioned
D)none of the mentioned

Question 22

Dry air consists of

A)oxygen, nitrogen
B)carbon dioxide
C)hydrogen, argon
D)all of the mentioned

Question 23

Complete dry air exists in nature.

Question 24

Which of the following is true?(here pa=partial pressure of dry air, pw=partial pressure of water vapour, p=atmospheric pressure)

A)p=pw
B)p=pa
C)p=pw + pa
D)all of the mentioned

Question 25

In a mixture of dry air and water vapour,

A)mole fraction of dry air = pa/p
B)mole fraction of water vapour = pw/p
C)both of the mentioned
D)none of the mentioned