Question

TE V XSU Using the thermochemical equation below, determme the change in enthalpy for the decomposition of 2.00 moles of C(ag). A(aq) + 2B(aq) + C(aq) AH--55.3 kJ 2Clog) Alaq) + 2Blog)

Answer 1

Explanation:

Step 1: Explanation

Hess' Law state:

If a chemical equation can be written as the sum of several other chemical equations, the enthalpy change of the first chemical equation equals the sum of the enthalpy changes of the other chemical equations.

Note:  

• if a chemical reaction is reversed then the sign of the enthalpy of the reaction reverses

Step 2: Calculation

A(aq) + 2B (aq) -----> C(aq)   ΔH = -55.3 kJ

When you reverse it it then

C(aq) ----> A(aq) + 2B (aq) ΔH = +55.3 kJ   [note: sign will reversed so it becomes +ve ]

For 1 moles of C enthaply changed = 55.3 kJ

so, for 2 mol of C enthapy change  will be = ( 55.3 kJ / 1 mol )  × 2 mol = 110.6 kJ