What volume of H reacted with C if 2 liters of CH4 were formed.

Given:
V (CH4) = 2 l

Find:
V (H2) -?

Solution:
1) Write the equation of a chemical reaction:
2H2 + C => CH4 ↑;
2) Calculate the amount of CH4 substance:
n (CH4) = V (CH4) / Vm = 2 / 22.4 = 0.09 mol;
3) Determine the amount of substance H2:
n (H2) = n (CH4) * 2 = 0.09 * 2 = 0.18 mol;
4) Calculate the volume H2:
V (H2) = n (H2) * Vm = 0.18 * 22.4 = 4 liters.

Answer: The volume of H2 is 4 liters.