120L C2H6 burns in oxygen, find the volume of consumed air.

Given:

V (C2H6) = 120 l

Find:

V (air) -?

Solution:

C2H6 + 7O2 = 2CO2 + 3H2O, – we solve the problem, relying on the composed reaction equation:

1) Find the amount of ethane that has reacted:

n (C2H6) = V: Vm = 120 L: 22.4 L / mol = 5.36 mol

2) We compose a logical expression:

if 1 mol of C2H6 requires 7 mol of O2,

then 5.36 mol C2H6 will require x mol O2,

then x = 37.52 mol.

3) Find the volume of oxygen spent on ethane combustion:

V (O2) = n * Vm = 37.52 mol * 22.4 l / mol = 840.448 l

4) Since the proportion of oxygen in the air is 20%, we multiply the volume of oxygen by 5 to find the volume of air:

V (air) = V (O2) * 5 = 840.448 l * 5 = 4202.24 l

Answer: V (air) = 4202.24 liters.