Question #5aa17

2 Answers
May 13, 2017

The chemical reaction is based from the number of moles of each species participating in the reaction and not by its volume.


This is how it works:

First, this is the reaction for the formation of water:
#H_2 + 1/2 O_2 rarr H_2O #

All chemical reactions are based on the number of moles (see those coefficients?) and not in their volume. Meaning 1 mole of #H_2#(hydrogen gas) will react with a half mole of #O_2#(oxygen gas) to form 1 mole of liquid water.

Jun 7, 2017

The answer lies in Avogadro's Hypothesis.


Avogadro's Hypothesis states that equal volumes of gases at the same temperature and pressure contain equal numbers of molecules.

The chemical equation for the formation of water is

#"2H"_2"(g)" + "O"_2"(g)" → 2"H"_2"O(g)"#

We could also write

#"2 mL + 1 mL → 2 mL"#


#"100 mL + 50 mL → 100 mL"#

The volumes will always be in the same #2:1:2# ratio as the coefficients in the balanced chemical equation.