Question

Which of the following processes are exothermic?
the formation of NaBr from its constituent elements in their standard state
the breaking the bond of I2
the sublimation of Li
the second ionization energy of Mg
None of the above are exothermic

Answer 1

Exothermic reactions release heat while endothermic reactions absorb heat.

To break bond of \(\mathrm{I}_{2}\), energy must be supplied and reaction is endothermic. To sublime Li (that is solid to gas transition), energy must be supplied and reaction is endothermic. Second ionization energy of Mg indicates energy required to remove second electron from Mg. So, second IE is also endothermic.

The formation of \(\mathrm{NaBr}\) from its elements, all at standard states, release heat. So, the process is exothermic.