Question

When 1.50 mol of CH4(g) reacts with excess Cl2(g) at constant pressure according to the chemical equation shown below, 1062 kJ of heat are released. Calculate the value of ?H for this reaction, as written. 2 CH4(g) + 3 Cl2(g) ? 2 CHCl3(l) + 3 H2(g) ?H = ? 1) -1420 kJ 2) -708 kJ 3) +708 kJ 4) +1420 kJ

Answer 1

The value of ?H for the reaction 2 CH4(g) + 3 Cl2(g) ? 2 CHCl3(l) + 3 H2(g) can be calculated by using stoichiometry and the given heat released. The value of ?H is 796.5 kJ, so the correct choice is 3) +708 kJ.

Step-by-step explanation:

The value of ΔH for the reaction 2 CH4(g) + 3 Cl2(g) ? 2 CHCl3(l) + 3 H2(g) can be calculated by using the given information. Since 1.50 mol of CH4(g) reacts and 1062 kJ of heat are released, we can use stoichiometry to find the value of ΔH. We can set up a proportion using the reaction coefficients and the given heat released:

2 mol CH4 / 1062 kJ = 1.50 mol CH4 / x kJ ⇒ x = (1062 kJ * 1.50 mol CH4) / 2 mol CH4 = 796.5 kJ

Therefore, the value of ΔH for this reaction is 796.5 kJ. Based on the choices given, the most appropriate answer is 3) +708 kJ.