# Problem: Using data from the following reactions and applying Hess's law, calculate the heat change for the slow reaction of zinc with water: Zn (s) + 2H2O (l) → Zn2+ (aq) + 2OH- (aq) + H2 (g)    ΔH°rxn = ? H+ (aq) + OH- (aq) → H2O (l)     ΔH°rxn, 1 = -56 kJ/mol H2O Zn (s) → Zn2+ (aq)    ΔH°rxn, 2 = -153.9 kJ 1/2 H2 (g) → H+ (aq)     ΔH°rxn, 3 = 0.0 kJ

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Using data from the following reactions and applying Hess's law, calculate the heat change for the slow reaction of zinc with water:

Zn (s) + 2H2O (l) → Zn2+ (aq) + 2OH- (aq) + H2 (g)    ΔH°rxn = ?

H+ (aq) + OH- (aq) → H2O (l)     ΔH°rxn, 1 = -56 kJ/mol H2

Zn (s) → Zn2+ (aq)    ΔH°rxn, 2 = -153.9 kJ

1/2 H2 (g) → H+ (aq)     ΔH°rxn, 3 = 0.0 kJ

What scientific concept do you need to know in order to solve this problem?

Our tutors have indicated that to solve this problem you will need to apply the Hess's Law concept. You can view video lessons to learn Hess's Law. Or if you need more Hess's Law practice, you can also practice Hess's Law practice problems.

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Based on our data, we think this problem is relevant for Professor Carrasquillo's class at UH.