When HBr(g) reacts with Cl2(g) to form HCl(g) and Br2(g) , 40.6 kJ of energy are evolved for each mole of HBr(g) that reacts. Write a balanced thermochemical equation for the reaction with an energy term in kJ as part of the equation. Note that the answer box for the energy term is case sensitive. Use the SMALLEST INTEGER coefficients possible and put the energy term (including the units) in the last box on the appropriate side of the equation. If a box is not needed, leave it blank. +

2HBr(g) + Cl2(g) —> 2HCl(g) + Br2(g) + 81.2 kJ

Explanation:

The equation for the reaction. This is given below:

HBr(g) + Cl2(g) —> HCl(g) + Br2(g)

The equation can be balance as follow:

There are 2 atoms of Cl on the left side and 1 atom on the right side. It can be balance by putting 2 in front of HCl as illustrated below:

HBr(g) + Cl2(g) —> 2HCl(g) + Br2(g)

There are 2 atoms of Br on the right and 1 atom on the left. It can be balance by putting 2 in front of HBr as illustrated below:

2HBr(g) + Cl2(g) —> 2HCl(g) + Br2(g)

Now the equation is balanced.

From the question given above, we were told that 40.6 kJ of energy are evolved for each mole of HBr(g) that reacts.

Since the balanced equation contains 2 mole of HBr, then energy evolved will be = 2 x 40.6 = 81.2KJ

Therefore, the thermodynamic equation can be written as:

2HBr(g) + Cl2(g) —> 2HCl(g) + Br2(g) + 81.2 kJ