Question

From the balanced chemical equations listed below, which equation best expresses the following word equation: Hydrogen gas plus oxygen gas yields water vapor plus energy?

2H2O (g) arrow 2H2 (g) + O2 (g) + energy

2H + O arrow 2HO + energy

2H2 (g) + O2 (g) arrow 2H2O (g) + energy

2H2 (g) + O2 (g) + energy arrow 2H2O (l)

Answer 1

It would be the third one. Your reactants (left side) are hydrogen gas (H2) and (+) oxygen gas (O2). The products are water vapor, which is a gas, so any of the ones that list 2H2O as a liquid (l) are automatically wrong, and then (+) gas.

Hydrogen gas (2H2) plus (+) oxygen gas (O2) yields (->) water vapor (2H2O(g)) plus (+) energy