Question

How much heat is released during the formation of 3.18 mol HCl(g) in this reaction: H2(g)+Cl2(g) → 2HCl(g) with a H of -184.6 kJ. Express your answer in kJ.

Answer 1

The given thermochemical reaction is between hydrogen gas and chlorine gas to form hydrogen chloride.

This can be represented as:

$H_{2}(g)+Cl_{2}(g)-->2HCl(g)$  Δ$H_{reaction}^{0}$=-184.6 kJ/mol

So when two moles of HCl is formed, 184.6 kJ of energy is released.

Calculating the heat released when 3.18 mol HCl (g) is formed in the reaction:

$3.18 molHCl*\frac{184.6kJ}{2molHCl} =293.5 kJ$

Therefore, 293.5 kJ of heat is released when 3.18 mol HCl is formed in the reaction between hydrogen and chlorine.

Answer 2

Answer: 293.5kJ

Explanation: As can be seen from the given reaction:

$H_2+Cl_2\rightarrow2HCl$

As $\Delta H$ of the reaction is negative, it means the heat is released and the reaction is exothermic.

When 2 moles of HCl are produced, energy released is 184.6kJ

When 3.18 moles of HCl are produced, energy released will be$=\frac{184.6kJ}{2}\times 3.18=293.5kJ$