## Chemistry and Chemical Reactivity (9th Edition)

a) Enthalpies of formation (kJ/mol): $KNO_3(s): -494.6, K_2S(s): -376.6, CO_2(g): -393.5$ $\Delta H_r=3\times -393.5-376.6-2\ times -494.6=-567.9\ kJ/mol$ b) $1.00\ g\div 302.36\ g/mol=3.31\ mmol$ $-567.9\ kJ/mol\times 0.00331\ mol=-1.88\ kJ$