Question

Ethylene (C2H4) is the starting material for the preparation of polyethylene. Although typically made during the processing of petroleum, ethylene occurs naturally as a fruit-ripening hormone and as a component of natural gas. The heat of reaction for the combustion of C2H4 is −1411 kJ/mol. How many grams of C2H4 must burn to give 59.0 kJ of heat?

Answer 1

1.17 grams

Step-by-step explanation:

Let's consider the balanced equation for the combustion of ethylene.

C₂H₄(g) + 3 O₂(g) → 2 CO₂(g) + 2 H₂O(l)

We can establish the following relations:

• 1411 kJ are released (-1411 kJ) when 1 mole of C₂H₄ burns.
• The molar mass of C₂H₄ is 28.05 g/mol.

The grams of C₂H₄ burned to give 59.0 kJ of heat (q = -59.0 kJ) is:

`-59.0kJ.(1molC_(2)H_(4))/(-1411kJ) .(28.05gC_(2)H_(4))/(1molC_(2)H_(4)) =1.17gC_(2)H_(4)`