# Determine the enthalpy for this reaction: mgcl2(s)+2naoh(aq)→mg(oh)2(s)+2nacl(aq)

Enthalpy H is a measure of the energy content of a system at constant pressure. Chemical reactions involve changes in enthalpy, ΔH, which can be measured and calculated: ΔHrxn∘=∑productsmΔHf∘−∑reactantsnΔHf∘ where the subscript “rxn” is for “enthalpy of reaction” and “f” is for “enthalpy of formation” and m and n represent the appropriate stoichiometric coefficients for each substance. The following table lists some enthalpy of formation values for selected substances. Substance ΔHf∘ (kJ/mol) NaOH(aq) −469.1 MgCl2(s) −641.8 NaCl(aq) −407.3 Mg(OH)2(s) −924.5 H2O(l) −285.8 Part A Determine the enthalpy for this reaction: MgCl2(s)+2NaOH(aq)→Mg(OH)2(s)+2NaCl(aq) Express your answer in kilojoules per mole to one decimal place. ΔHrxn∘ = kJ/mol SubmitMy AnswersGive Up Part B Consider the reaction Mg(OH)2(s)→MgO(s)+H2O(l) with enthalpy of reaction ΔHrxn∘=37.5kJ/mol What is the enthalpy of formation of MgO(s)? Express your answer in kilojoules per mole to one decimal place. ΔHf∘ = kJ/mol Submit