Hydrogen fuel cells are a promising alternative to gasoline engines in part because they release water instead of carbon dioxide. In a hydrogen fuel cell, hydrogen gas (H₂) and oxygen gas (O₂) react to make water as shown below. Which of the following statements is a true statement about how this reaction occurs? 2 H₂(g) + O₂(g) → 2 H₂O(g)

Question

Quizplus · Accepted Answer

The balanced chemical equation shows that one molecule of hydrogen gas (H₂) must react with one molecule of oxygen gas (O₂) to produce one molecule of water (H₂O), indicating that a single collision between a hydrogen molecule and an oxygen molecule is necessary. Choices C and D are incorrect because neither an O-H bond nor an H-H bond is formed or broken in this reaction. Choice E is incorrect because changing state (such as from a gas to a liquid) is not indicated in the equation. Choice A is incorrect because it suggests that two molecules of hydrogen gas are required in the reaction, rather than one.

Hydrogen Fuel Cells Are a Promising Alternative to Gasoline Engines