The ionisation enthalpy of sodium is 5.14 eV. How many k cal of energy is required to ionise all atoms present in one gram of gaseous Na atoms?

Explanation

`1 eV "atom"^(-1) = 23 k "cal mol"^(-1)`
Energy required to ionise all atoms of 23 grams (one mole) of gaseous Na atoms `= 23 xx 5.14 k cal `
Energy required for ionisation of all atoms present `(23 xx 5.14)/(23)`
  in one gram of gaseous Na atoms = 5.14 k cal.