Describe what happens to the temperature, the volume, and the phase composition
ID: 885084 • Letter: D
Question
Describe what happens to the temperature, the volume, and the phase composition (number of moles of liquid or vapor present) following the addition of 400 J of heat from 1 mol of pure water initially in each of the following states. Assume that the pressure is maintained constant at 1 bar throughout and that the gas behaves ideally.
a) Liquid water initially at 85°C.
b) Liquid water initially at 100°C.
c) Water vapor initially at 100°C.
d) Which of the three processes above involves the largest amount of work done on or by the system? What is the sign of w?
Explanation / Answer
Solution :-
Describe what happens to the temperature, the volume, and the phase composition (number of moles of liquid or vapor present) following the addition of 400 J of heat from 1 mol of pure water initially in each of the following states. Assume that the pressure is maintained constant at 1 bar throughout and that the gas behaves ideally.
a) Liquid water initially at 85°C. = Liquid water will absorb the heat and rise in the temperature of the liquid water (volume will remain same) vapor pressure of the water will increase.
b) Liquid water initially at 100°C.= Liquid water at 100 C absorb the heat and liquid will convert to the vapor at the same temperature.(since the liquid is changing to the vapor therefore volume will increase)
c) Water vapor initially at 100°C= Vapor at 100 C will absorb the heat and rise in the temperature above 100 C. Volume will increase since vapor expands at temperature increases.
d) Which of the three processes above involves the largest amount of work done on or by the system? What is the sign of w?
Solution :- Process given in the option b will have the maximum work because the volume of the system increase significantly. and the sign for the work done will be negative because system is doing work on surrounding.