Chemistry · Thermochemistry
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Which of the following equations represents a reaction for which the enthalpy change of formation of water, ΔH form?
- A
H+ (aq) + OH- (aq) -> H2O(l)
- B
H2 (g) + ½ O2 (g) -> H2O (l)
- C
H2O(g) + H2O(l)
- D
H2O(s) -> H2O(l)
The correct answer is the reaction H2 (g) + ½ O2 (g) -> H2O (l), as it represents the standard enthalpy change of formation for water. This involves forming one mole of water from its basic elements, hydrogen and oxygen, in their standard states. Option A describes a neutralization reaction, not a formation reaction. Option C is a mixture of phases of water, not a formation from elements. Option D describes a phase change, not a chemical formation reaction.
This reaction represents the neutralization of an acid and a base, not the standard formation of water from its elements.
This is the standard enthalpy change of formation for water, where hydrogen gas reacts with oxygen gas to form liquid water.
This equation does not represent a chemical reaction, but rather involves a physical change between states of water.
This is a phase change from solid to liquid water, not a formation reaction from elemental constituents.
Tagged under Chemistry · Thermochemistry · 2017