Problem 4
calculate the mass of ethane, c2h6, which must be burned to produce 100 kj of heat.

2 czh6(9) + 7 02(9) > 4co2(g) + 6 h2o(1) ah = -3120 kj

1.93 g

We are given;

The chemical equation;

2C₂H₆(g) + 7O₂(g) → 4CO₂(g) + 6H₂O(l) ΔH = -3120 kJ

We are required to calculate the mass of ethane that would produce 100 kJ of heat.

Number of moles that will produce 100 kJ will be;

= (2 × 100 kJ) ÷ 3120 kJ)

= 0.0641 moles

Therefore;

Mass of ethane = 0.0641 moles × 30.07 g/mol

                          = 1.927 g

                          = 1.93 g

Thus, the mass of ethane that would produce 100 kJ of heat is 1.93 g