Question

The heat of polymerization of ethylene is 25 Kcal/mol. The amount of heat generated during the polymerization of 5.6 kg polyethylene is .............. Kcal. (Round off to the nearest integer)

Hint:

Always convert given mass of polymer into moles of monomer units before multiplying with the heat of polymerization.

Answer 1

Correct Answer: 4975

Step 1: Molar mass of ethylene unit.
Polyethylene is formed from ethylene monomers. Molar mass of ethylene (\(C_2H_4\)) is: \[ M = 2 \times 12 + 4 \times 1 = 28 \; \text{g/mol} \]

Step 2: Number of moles in 5.6 kg polyethylene.
\[ n = \frac{\text{Mass}}{\text{Molar mass}} = \frac{5600}{28} = 200 \; \text{mol} \]

Step 3: Heat of polymerization.
Given heat of polymerization per mole of ethylene = \(25 \; \text{Kcal/mol}\). Total heat evolved: \[ Q = 200 \times 25 = 5000 \; \text{Kcal} \] Final Answer: \[ \boxed{5000 \; \text{Kcal}} \]