The ionization enthalpies of Li and Na are 520 kJ m o l - 1 and 495 kJ m o l - 1 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

Question

The ionization enthalpies of Li and Na are 520 kJ m o l - 1 and 495 kJ m o l - 1 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, 52 J, 49.5 J, 520 J, 495 J, 49.5 J, 52 J, 495 J, 520 J

MARKS App · Accepted Answer

Number of moles = weight in gm atomic weight Number of moles Li = 7 1000 × 7 = 1 0 - 3 Number of moles of Na = 23 1000 × 23 × = 1 0 - 3 Amount of energy = moles × energy needed for 1 mole. So, the amounts of energies required for 1 0 - 3 mole each of Li and Na are 520 kJ × 1 0 - 3 or 520 J and 495 J respectively.

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