How much air is needed to completely burn 6 kg of coal?

Given: Solution:
m (C) = 6 kg (6000 g) C + O2 = CO2
1. Find the amount of substance C:
Find: n (C) = m / M = 6000/12 = 500 mol
V (air) -? 2. Find the amount of substance O2:
n (О2) = n (С) = 500 mol
3. Find the volume of O2:
V (O2) = n (O2) x Vn (O2) =
= 500 mol x 22.4 l / mol = 11200 l
4. Find the volume of air. Oxygen in
air by volume about 21%, hence:
V (air) = V (O2) / 0.21 = 53333.3 l
Answer: 53333.3 l