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 70.4 kJ of heat?

Answer 1

Answer:

1.40 grams of C2H4 must burn to give 70.4 kJ of heat

Explanation:

The heat of reaction for the combustion of C2H4 is −1411 kJ/mol, means that 1 mol of ethylene releases 1411 kJ. The (-) means that reaction is exothermic.

1st step. Apply a rule of three

1411kJ are released in 1 mol, how many moles of etylene release  in 70.4 kJ.

1411 kJ _____ 1 mol

70.4 kJ _____ (70.4 kJ . 1 m) / 1411 kJ = 0.0498 moles

2nd step. Convert the moles in mass, by molar mass

Molar mass ethylene: 28.05 g/m

Molar mass . moles = mass

0.0498 m . 28.05 g/m = 1.40 g