Equal volumes of different gases (at the same T and P) contain equal numbers of particles.
The Implication
If the number of moles doubles, the volume doubles.
\( V \propto n \)
Example: Ratio of Volumes
Reaction:
2H_2(g) + O_2(g) \to 2H_2O(g)
Ratio: 2 : 1 → 2
If you react 20 cm³ of H₂, you need 10 cm³ of O₂, and you produce 20 cm³ of steam.
Standard Molar Volume
At STP (273 K, 100 kPa):
22.7 dm³
Per mole of gas
Student Practice Set
1.
For \( N_2(g) + 3H_2(g) \to 2NH_3(g) \), what volume of hydrogen reacts with 10 dm³ of nitrogen?