## Chemistry and Chemical Reactivity (9th Edition)

$-3.090 \ MJ/mol$
From the definition of heat capacity: $(775\ g\times 4.184\ J/g.K+893\ J/g)\times (31.69-22.50)\ K=38.0\ kJ$ Since it's an exothermic process, the sign is negative. Number of moles of benzoic acid: $1.50\ g\div 110.11\ g/mol=0.0136\ mol$ Hence: $\Delta U=-38.0\ kJ/0.0123\ mol=-3.090 \ MJ/mol$