CH₄ + 4Cl₂(g) → CCl₄(g) + 4HCl(g), ΔH = -434 kJ Based on the above reaction, what energy change occurs when 1.7 mol of methane reacts?

Question

Quizplus · Accepted Answer

First, we need to write the balanced chemical equation for the combustion of 1 mole of methane:

CH4(g) + 2O2(g) → CO2(g) + 2H2O(g)

From the equation, we can see that 1 mole of methane produces 802 kJ of energy. Therefore, 1.7 mol of methane will produce:

1.7 mol CH4 × 802 kJ/mol CH4 = 1363.4 kJ

We can assume that all of this energy will be released in the reaction in question. Therefore, we need to convert the kJ to J:

1363.4 kJ × 1000 J/kJ = 1.3634 × 10^6 J

Finally, we need to divide by the coefficient of CH4 and multiply by the coefficient of CCl4 to get the answer in joules:

1.3634 × 10^6 J ÷ 1 × 1 ÷ 1 = 1.3634 × 10^6 J

Now we can compare this with the answer choices:

A) 2.6 × 10^15 J is released. (Too high) 
B) 7.4 × 10^15 J is released. 
C) 2.6 × 10^15 J is absorbed. (Wrong sign) 
D) 7.4 × 10^15 J is absorbed. (Wrong sign) 
E) 4.3 × 10^12 J is released. (Too low)

Therefore, the correct answer is B.

CH4 + 4Cl2(g) → CCl4(g) + 4HCl(g), ΔH = -434

CH₄ + 4Cl₂(g) → CCl₄(g) + 4HCl(g), ΔH = -434