Deck 12: Thermodynamic Property Relations

Question 1

A substance whose Joule-Thomson coefficient is positive is throttled to a lower pressure. During this process, (select the correct statement)

A)the temperature of the substance will increase.
B)the temperature of the substance will decrease.
C)the entropy of the substance will remain constant.
D)the entropy of the substance will decrease.
E)the enthalpy of the substance will decrease.

Answer 1

the temperature of the substance will decrease.

Question 2

An ideal gas is throttled to a lower pressure. During this process, (select the correct statement)

A)the temperature of the gas will increase.
B)the temperature of the gas will decrease.
C)the temperature of the gas will remain constant.
D)the entropy of the gas will decrease.
E)the enthalpy of the gas will decrease.

Answer 2

the temperature of the gas will remain constant.

Question 3

Of the five statements below about the specific heat difference C_p - C_v, chose the wrong one:

A)The specific heat difference C_p - C_v of a substance is positive or zero.
B)The specific heat difference C_p - C_v at a given absolute temperature T is proportional to T.
C)The specific heat difference C_p - C_v is zero for incompressible substances.
D)The specific heat difference C_p - C_v of an ideal gas is independent of temperature.
E)The specific heat difference C_p - C_v is proportional to isothermal compressibility.

Answer 3

The specific heat difference C_p - C_v is proportional to isothermal compressibility.

Question 4

Based on the generalized charts, the error involved in the enthalpy of CO₂ at 350 K and 9 MPa if it is assumed to be an ideal gas is

A)0
B)20%
C)55%
D)30%
E)70%

Question 5

Based on data from the steam tables, the Joule-Thompson coefficient of steam at 3 MPa and 300°C is approximately

A)0
B)-5°C/MPa
C)12°C/MPa
D)8°C/MPa
E)26°C/MPa