Calculate the standard enthalpy change for the following reaction at 25 °C.

MgCl2(s)+H2O(l)-->MgO(s)+2HCl

To calculate the standard enthalpy change for the given reaction at 25 °C, we need to use the standard enthalpy of formation values for each compound involved in the reaction. The standard enthalpy of formation (ΔHf°) is the enthalpy change that occurs when one mole of a compound is formed from its elements in their standard states.

First, we need to identify the standard enthalpy of formation values for each compound involved in the reaction. The standard enthalpy of formation values can be found in reference books or online databases.

The standard enthalpy of formation values for the compounds involved are:
- MgCl2(s): -641.69 kJ/mol
- H2O(l): -285.83 kJ/mol
- MgO(s): -601.8 kJ/mol
- HCl(g): -92.3 kJ/mol

Next, we need to determine the stoichiometric coefficients for each compound in the balanced equation:
1 MgCl2(s) + 2 H2O(l) → 1 MgO(s) + 2 HCl(g)

Now we can calculate the standard enthalpy change (ΔH°) for the reaction using the formula:
ΔH° = ΣnΔHf°(products) - ΣnΔHf°(reactants)

ΔH° = (1 * -601.8 kJ/mol) + (2 * -92.3 kJ/mol) - (1 * -641.69 kJ/mol) - (2 * -285.83 kJ/mol)

Simplifying the equation:
ΔH° = -601.8 kJ/mol - 184.6 kJ/mol + 641.69 kJ/mol + 571.66 kJ/mol

Calculating the enthalpy change:
ΔH° = 526.85 kJ/mol

Therefore, the standard enthalpy change for the given reaction at 25 °C is 526.85 kJ/mol.

dHf rxn = (n*dHf products) - (n*dHf reactants)