Which of the following reactions is expected to have a positive change in entropy?
Practice Questions
1 question
Q1
Which of the following reactions is expected to have a positive change in entropy?
N2(g) + 3H2(g) → 2NH3(g)
C(s) + O2(g) → CO2(g)
2H2O(l) → 2H2(g) + O2(g)
CaCO3(s) → CaO(s) + CO2(g)
The decomposition of liquid water into gaseous hydrogen and oxygen increases the number of gas molecules, leading to a positive change in entropy.
Questions & Step-by-step Solutions
1 item
Q
Q: Which of the following reactions is expected to have a positive change in entropy?
Solution: The decomposition of liquid water into gaseous hydrogen and oxygen increases the number of gas molecules, leading to a positive change in entropy.
Steps: 6
Step 1: Understand what entropy means. Entropy is a measure of disorder or randomness in a system.
Step 2: Identify the reactions being considered. Look for reactions that produce more gas molecules.
Step 3: Consider the decomposition of liquid water. The reaction is: 2 H2O (liquid) → 2 H2 (gas) + O2 (gas).
Step 4: Count the number of molecules before and after the reaction. Before: 2 molecules of H2O (liquid). After: 2 molecules of H2 (gas) + 1 molecule of O2 (gas) = 3 gas molecules.
Step 5: Note that increasing the number of gas molecules generally increases disorder. More gas molecules mean more ways to arrange them.
Step 6: Conclude that the decomposition of liquid water into gas increases entropy, leading to a positive change in entropy.
