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Polyethylene is prepared from calcium carbide through the sequence shown below: CaC2 + 2H2O → Ca(OH)2 + C2H2 C2H2 + H2 → C2H4 nC2H4 → (–CH2–CH2–)n What mass of polyethylene can be produced from 64.1 kg of CaC2?

1. 7 kg
2. 14 kg
3. 21 kg
4. 28 kg

Correct answer: 28 kg

Solution

The reaction shows that 1 mole of calcium carbide (CaC2) produces 1 mole of acetylene (C2H2), which then converts to polyethylene (–CH2–CH2–)n. Given the molar mass of CaC2 and the stoichiometry of the reactions, 64.1 kg of CaC2 yields enough C2H4 to produce 28 kg of polyethylene.

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