Question 1
Which of the following best describes entropy?
A. The measure of energy in a system.
B. The measure of disorder or randomness in a system.
C. The measure of heat transfer in a system.
D. The measure of work done by a system.
Question 2
What is the unit of entropy in the International System of Units (SI)?
A. Joule
B. Kelvin
C. Joule per Kelvin
D. Kelvin per Joule
Question 3
Which phase of matter generally has the highest entropy?
A. Solid
B. Liquid
C. Gas
D. Aqueous
Question 4
If a reaction results in an increase in the number of gaseous molecules, what can be said about the change in entropy?
A. Entropy decreases.
B. Entropy remains unchanged.
C. Entropy increases.
D. Cannot be determined without additional information.
Question 5
Which of the following factors does NOT affect entropy?
A. Temperature
B. Pressure
C. Volume
D. Colour
Question 6
a) Define entropy (S) in thermodynamics and explain its relationship to the degree of disorder in a system. [3]
b) Calculate the change in entropy (ΔS) when 2 moles of ice (H2O(s)) at -10°C are melted to form 2 moles of water (H2O(l)) at 20°C. Given ΔHfus° = 6.01 kJ/mol and ΔSfus° = 22.0 J/(mol·K). [2]
Question 7
a) Explain the concept of microstates in thermodynamics and how it is related to entropy (S). [3]
b) Calculate the change in entropy (ΔS) when 1 mole of nitrogen gas (N2(g)) at 25°C and 1 atm pressure is allowed to expand irreversibly into a vacuum until its volume doubles. Assume ideal behaviour. [2]
Question 8
a) Describe the role of temperature in the spontaneity of chemical reactions according to Gibbs free energy (ΔG). [3]
b) Calculate the change in entropy (ΔS) when 2 moles of chlorine gas (Cl2(g)) at 100°C and 2 atm pressure are compressed to 1 mole of chlorine gas at the same temperature and pressure. Assume ideal behaviour. [2]
Question 9
a) Define entropy (S) in thermodynamics and explain how it relates to the dispersal of energy. [3]
b) Calculate the change in entropy (ΔS) when 1 mole of a monoatomic ideal gas undergoes an isothermal expansion at 298 K, doubling its volume. [2]
c) Discuss the factors that affect the spontaneity of a chemical reaction based on changes in entropy. [3]
Question 10
a) Explain the concept of microstates in thermodynamics and how it is related to entropy (S). [3]
b) Calculate the change in entropy (ΔS) when 1 mole of water (H2O) freezes at its standard freezing point, assuming ideal behaviour. Given ΔHfus° = 6.01 kJ/mol. [3]
c) Discuss the significance of the sign of ΔS in determining whether a process is spontaneous or non-spontaneous. [2]