Chapter 13, Problem 80E

Practice Exercise 1
When 0.243 g of Mg metal is combined with enough HCI to make 100 mL of solution in a constant-pressure calorimeter, the following reaction occurs:

Mg(s) + 2 HCl(aq)→MgCl₂(aq)+H₂(g)

If the temperature of the solution increases from 23.0 to 34.1 °C as a result of this reaction, calculate ΔH in kJ/mol Mg. Assume that the solution has a specific heat of 4-18 J/g-^°C and a density of 1.00 g/mL.

1. -19.1 kJ/mol
2. -111 kJ/mol
3. -191kJ/mol
4. -464kJ/mol
5. -961 kJ/mol