## Chemistry and Chemical Reactivity (9th Edition)

The reaction is exothermic because the enthalpy change of reaction is negative. $1.25\ g\div 30.00\ g/mol=0.0417\ mol\ NO$ From stoichiometry: $0.0208\ mol\ O_2$ Enthalpy change: $-114.1\ kJ/mol\times 0.0208\ mol=-2.38\ kJ$