Question

The ionization energy of sodium is $495kJ/mol$. How much energy is needed to convert atoms present in 2.3 $mg$ of sodium into sodium ions?

• A. 4.95 $J$
• B. 49.5 $J$
• C. 495 $J$
• D. 0.495 $J$

Answer 1

The correct option is B 49.5 $J$

Given, mass of $Na$ atoms = 2.3 $mg$ = $2.3\times {10}^{-3}$ g
So, number of moles of $Na$ = $\frac{2.3\times {10}^{-3}}{23}={10}^{-4}mol$
Energy involved in ionization of 1 mole of $Na$ atom is $=495kJ/mol$
So, energy involved in ionization of ${10}^{-4}$ mol $Na$ atom is: = $495\times {10}^3\times {10}^{-4}$ J = 49.5 $J$