The mass of methane is 80 g, the yield is 60% acetylene, find the volume of acetylene.

1. Acetylene is obtained from methane by the pyrolysis reaction:

2CH4 → C2H2 + 3H2;

2. since the known data relate to the reagent from the left side of the equation, then the calculation is carried out through theoretical chemical quantities:

ntheor (CH4) = m (CH4): M (CH4);

M (CH4) = 12 + 4 = 16;

ntheor (CH4) = 80: 16 = 5;

3. we find the theoretical amount of acetylene, according to its reaction, it is half that of methane:

ntheor (C2H2) = 5: 2 = 2.5;

4.translate the theoretical amount of acetylene into practical, using the product yield:

npract (C2H2) = ntheor (C2H2) * ν (in fractions);

npractic (C2H2) = 2.5 * 0.6 = 1.5 mol;

5. Determine the volume of the obtained acetylene:

V (C2H2) = npract (C2H2) * Vm

V (C2H2) = 1.5 * 22.4 = 33.6 dm3.

Answer: 33.6 dm3.