Use the standard enthalpies of formation for the reactants and products to solve for the ΔHrxn for the following reaction. (The ΔHf of Ca(OH)2 is -986.09 kJ/mol and liquid H2O is -285.8 kJ/mol.)

Ca(s) + 2H2O(l) Ca(OH)2 (s) + H2(g)

ΔHrxn = ?

The reaction is ?

Question

Use the standard enthalpies of formation for the reactants and products to solve for the ΔHrxn for the following reaction. (The ΔHf of Ca(OH)2 is -986.09 kJ/mol and liquid H2O is -285.8 kJ/mol.)

Ca(s) + 2H2O(l)  Ca(OH)2 (s) + H2(g)

ΔHrxn =  ?

The reaction is   ?

aaronq · Answer

Use the standard enthalpies (from a table in your textbook or online).

$\Delta H_{rxn}=\underbrace{\Sigma H_f}_{products}-\underbrace{\Sigma H_f}_{reactants} $