Question

The ionization enthalpies of Li and Na are 520 kJ/ mol
and 495 kJ/ mol
respectively. The energy required to convert all the atoms present in 7 mg of Li vapours and 23 mg of sodium vapours of their respective gaseous cations respectively are:

Answer 1

Given,

The ionization enthalpies of Li and Na are 520 kJ/ mol and 495 kJ/ mol respectively.

To find,

The energy required to convert all the atoms present in 7 mg of Li vapours and 23 mg of sodium vapours of their respective gaseous cations respectively.

number of moles of Li = 7mg/{7g/mol} = 0.001 mol

so energy required to convert all the atoms present in 7 mg of Li vapours, E = ionisation enthalpy × no of moles

= 520 kJ/mol × 0.001 mol

= 520 × 10³ × 0.001 J

= 520 J

number of moles of Na = 23mg/{23g/mol} = 0.001 mol

so energy required to convert all the atoms present in 23 mg of Na vapours, E = ionisation enthalpy × no of moles

= 495 kJ/mol × 0.001 mol

= 495 × 10³ × 0.001 J

= 495 J