Question

which of the following processes is spontaneous?

choose one or more:

• steam condenses on a cold window.
• charcoal is converted to carbon dioxide when ignited in air.
• \\(\text{ch}_4(g)\\) and \\(\text{o}_2(g)\\) are formed from \\(\text{co}_2(g)\\) and \\(\text{h}_2\text{o}(\ell)\\).
• sugar dissolves in hot water.

Explanation:

Define thermodynamic spontaneity

A spontaneous process occurs naturally without external intervention.

Analyze steam condensation

Steam condensing on a cold window occurs naturally. Heat flows from hot steam to the cold window.

Analyze charcoal combustion

Charcoal burning in air is highly spontaneous once ignited. It releases energy and increases entropy.

Analyze reverse combustion

Forming methane and oxygen from carbon dioxide and water is non-spontaneous. It requires significant energy input.

Analyze sugar dissolution

Sugar dissolving in hot water occurs spontaneously. The process increases system entropy.

Answer:

• Steam condenses on a cold window. (Correct answer)
• Charcoal is converted to carbon dioxide when ignited in air. (Correct answer)
• \(\text{CH}_4(g)\) and \(\text{O}_2(g)\) are formed from \(\text{CO}_2(g)\) and \(\text{H}_2\text{O}(l)\).
• Sugar dissolves in hot water. (Correct answer)