Question

Given the following:

Measurement Reaction 1 (Mg + HCl)
Mass of HCl (g) 100.50
Mass of solid (g) 0.20
Total mass of reactants, m (g) (add the masses above) 100.70
Initial Temperature (°C) 22.5
Temperature furthest from initial temperature(°C) 31.3
∆T(°C) Subtract the two temperatures above) 8.8

Given Reaction 1: Mg(s) + 2HCl(aq) ⟶ MgCl2(aq) + H2(g)

What is the ∆H (kJ/mol)?

Answer 1

Answer:

∆H = - 450 kJ/mol

Explanation:

You can calculate the change in enthalpy provided we have the heat of solution (q). That would be the only approach to this problem. But this approach is only possible if we have a specific set-up; we would have to use a calorimeter. So then the reactants are taken as the system, and water as the surroundings. When calculating q, the heat of the solution, we take 4.18. Remember that heat is flowing from the reaction mixture, to the water, from the system to surroundings, so it's exothermic and ∆H = negative:

Answer 2

Answer:

- 450 kJ/mol

Explanation:

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