Chemical Engineering Thermodynamics - Study Mode

[#241] Law of corresponding states says that
Correct Answer

(A) Two different gases behave similarly, if their reduced properties (i.e. P, V and T) are same

Explanation

Solution: Law of corresponding states : at same reduced properties all the gases behaves similarly. This is the statement of corresponding states and the reduced property is defined as the state variables of a fluid scaled by the state properties at its critical point.

[#242] Free energy, fugacity and activity co-efficient are all affected by change in the temperature. The fugacity co-efficient of a gas at constant pressure ____with the increase of reduced temperature.
Correct Answer

(B) Increases

[#243] Any substance above its critical temperature exists as
Correct Answer

(C) Gas

Explanation

Solution: As above the critical point there is no demarcation between the liquid and vapor we call the matter as gas.

[#244] First law of thermodynamics is mathematically stated as
Correct Answer

(A) dQ = dE + dW

Explanation

Solution: First law of thermodynamics sates that energy can’t be destroyed instead it converts from one form to another form only. The two forms of energy in transits are heat and work with which the system contacts the surroundings there by changing its internal energy: If we express this in mathematical form: [delta Q=dU+delta W] Where, [delta Q= ext{ heat given to the system}] [delta W= ext{work done by the system}]

[#245] A cyclic engine exchanges heat with two reservoirs maintained at 100 and 300°C respectively. The maximum work (in J) that can be obtained from 1000 J of heat extracted from the hot reservoir is
Correct Answer

(A) 349

Explanation

Solution: Since to obtain the maximum work we have to use an reversible heat engine for an reversible heat engine operating between two reservoirs the efficiency is given by: $$eqalign{
& mathop eta limits^iota = frac{W}{{{Q_1}}} = frac{{{T_1} - {T_2}}}{{{T_1}}} cr
& Rightarrow W = 1000left( {frac{{300 - 100}}{{573}}}
ight) cr
& Rightarrow W = 349J cr} $$ Here $${{T_1}}$$ and $${{T_2}}$$ are temperatures in thermodynamic scale or kelvin temperatures.