In which of the following reactions is the entropy change expected to be negativ

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Question: In which of the following reactions is the entropy change expected to be negative?

Options:

Correct Answer: N2(g) + 3H2(g) → 2NH3(g)

Solution:

The reaction N2(g) + 3H2(g) → 2NH3(g) results in a decrease in the number of gas molecules, leading to a negative change in entropy.

In which of the following reactions is the entropy change expected to be negative?

In which of the following reactions is the entropy change expected to be negative?

Correct Answer: N2(g) + 3H2(g) → 2NH3(g)

Step 1: Understand what entropy means. Entropy is a measure of disorder or randomness in a system.
Step 2: Identify the states of matter involved in the reaction. Gases have higher entropy than liquids or solids.
Step 3: Look at the reaction given: N2(g) + 3H2(g) → 2NH3(g). Count the number of gas molecules on each side.
Step 4: On the left side, there are 1 (N2) + 3 (H2) = 4 gas molecules.
Step 5: On the right side, there are 2 gas molecules (2NH3).
Step 6: Compare the number of gas molecules: 4 (left) vs 2 (right).
Step 7: Since the number of gas molecules decreases from 4 to 2, the disorder of the system decreases.
Step 8: A decrease in disorder means the entropy change is negative.

Entropy Change – Entropy is a measure of disorder in a system; a decrease in the number of gas molecules typically leads to a decrease in entropy.
Gas Molecule Count – Reactions that result in fewer gas molecules generally have a negative entropy change due to reduced disorder.