Calculate how much air is required for the complete oxidation of acetylene m = (66.56).

Given:
m (C2H2) = 66.56 g

To find:
V (air) -?

Decision:
1) Write the equation of a chemical reaction:
2C2H2 + 5O2 => 4CO2 + 2H2O;
2) Using the periodic system of D.I.Mendeleev, calculate the molar mass of C2H2, which will be numerically equal to the molecular mass:
Mr (C2H2) = Ar (C) * 2 + Ar (H) * 2 = 12 * 2 + 1 * 2 = 26 g / mol;
3) Calculate the amount of substance C2H2:
n (C2H2) = m (C2H2) / Mr (C2H2) = 66.56 / 26 = 2.56 mol;
4) Determine the amount of substance O2 (taking into account the coefficients in the reaction equation):
n (O2) = n (C2H2) * 5/2 = 2.56 * 5/2 = 6.4 mol;
5) Calculate the volume of O2:
V (O2) = n (O2) * Vm = 6.4 * 22.4 = 143.36 L;
6) Calculate the air volume:
V (air) = V (O2) * 100% / φ (O2) = 143.36 * 100% / 21% = 682.67 liters.

Answer: The air volume is 682.67 liters.