Question

Propane burns according to the following reaction:

C3H8 + 5O2 → 3CO2 + 4H2O

What volume of carbon dioxide is produced if 25.0 m3 of propane at atmospheric pressure is combusted?

Answer 1

Propane burns in air according to the following equation:

C

3

H

8

+5O

2

→3CO

2

+4H

2

O.

1 mole of propane combines with 5 moles of oxygen.

Volume is directly proportional to the number of moles.

1 cm

3

of propane will combine with 5 cm

3

of oxygen.

Only 20% of air contains oxygen. So 1000 cm

3

of air contains 1000cm

3

×

100

20

=200cm

3

of oxygen.

The volume of propane that is consumed on using 1000 cm

3

of air is

5

200cm

3

=40cm

3

.

Answer 2

Reaction

C₃H₈ + 5O₂ → 3CO₂ + 4H₂O

Avogadro: at the same T and P, the ratio of gas volume = the ratio of gas moles

volume of CO₂ = 3/1 x 25 = 75 m³