Question

How much energy, in kJ, will be produced when 7.1g of chlorine atoms are converted to $Cl^{-}$ ions in gaseous state? [Given : Electron affinity of chlorine = – 3.7 ev; 1 ev = 96.49 kJ/mole]

Answer 1

Electron affinity means energy released by gas during it changes to ion state from gas state.

Here, chlorine releases 3.7eV energy when it transforms from chlorine gas to chlorine ion. For 1 mole chlorine, the released energy is

                                          3.7eV = 357.013 kJ/mole

Now, 1 mole Chlorine = 35.5 gm.

35.5 gm chlorine when changes completely into $Cl^{-}$ ion releases 357.013 kJ energy

7.1 gm chlorine when changes completely into $Cl^{-}$ ion releases  

                         $\frac{357.013}{35.5}\times 7.1=71.4KJ$