Enthalpy H is a measure of the energy content of a changes in enthalpy, 1, which

Question

Enthalpy H is a measure of the energy content of a changes in enthalpy, 1, which ean be measued and Determine the enthalpy for this reaction MgCh(s) + 2NaOH(aq)Mg(OH)1 (s) + 2NaCl(aq) Express your answer in kilojoules per mole to one decimal place where the subscript "r is for "enthaipy of reaction" and T is for "enthalpy of formation" and m and n represent kJ/mol The following table lists sonertaty of formation | | SubmitMy Answers Give Up Substance 1,"(k//mol) Part B Mg(OH)2() MgO(s)+H,O(0) with enthalpy of reaction What is the enthalpy of fomation of MgO() Express your answer in kilojoules per mole to one decimal place. H:00) Hints 20 2 8 2

Explanation / Answer

Part A-

MgCl2(s) + 2NaOH(aq) --> Mg(OH2)(s) + 2NaCl(aq)

DeltaH rxn°= [delta Hf(Mg(OH)2 + 2*deltaHf(NaCl)]

- [deltaHf(MgCl2) + 2*deltaHf(NaOH)]

Keeping the values from the table-

DeltaHrxn° =[-924.5kJ/mol +2(-407.3kJ/mol)]

- [-641.8kJ/mol +2(-469.1kJ/mol)]

DeltaHrxn° = -1329.8kJ/mol -(-1580kJ/mol)

DeltaHrxn°= 250.2kJ/mol

Part B-

Mg(OH)2(s)---> MgO(s) + H2O(l)

DeltaHrxn° = [deltaHf(MgO) + deltaHf(H2O)]

- [(deltaHf(Mg(OH)2]

Keeping the values-

37.5kJ/mol = dektaHf(MgO) + (-285.8kJ/mol) - (-924.5kJ/mol)

DeltaHf(MgO) = 37.5kJ/mol +285.8kJ/mol -924.5kJ/mol

DeltaHf(MgO(s))= -601.2kJ/mol

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