CHEM1084_U3_LAB 3_Prelab Pre Lab Questions 1. Define entropy. What are the units of entropy? 2. How does the entropy of the system change for the following processes (a) Melting of ice (b) Condensing...

CHEM1084_U3_LAB 3_Prelab
Pre Lab Questions
1. Define entropy. What are the units of entropy?
Solution- A system requires thermal energy for work done. The system’s thermal energy per unit temperature that is unavailable for some useful work is known as entropy. Entropy is also called the randomness of the system or molecular disorder of the system. The greater the randomness the higher the entropy will be.
According to Clausius's statement, the entropy always increases if an amount of heat flows into a large heat reservoir. That is,
∆S = Q/T,
Where ∆S changes in entropy (increase), Q is heat flow into the system and T is the temperature of the reservoir.
Note:- The temperature of the reservoir is above absolute zero.
Units of Entropy:-
Entropy per unit mass is designated by kJ/ kg K.
In SI Unit- Joules per Kelvin per Mole (J/Kmol).
In SI base units – kg m2/ s2K
2. How does the entropy of the system change for the following processes (a) Melting of ice (b) Condensing of water vapor?
Solution-
Whenever there is a change in phase of the system, there is a change in entropy. Therefore
(a) Melting of ice (solid) into water (liquid) increases randomness and disorder of the molecules hence the entropy increases.
∆S >0
(b) Condensation...