Q17E - Chemistry (OpenStax)

Question

Give balanced equations for the overall reaction in the electrolysis of molten lithium chloride and for the reactions occurring at the electrodes. You may wish to review the chapter on electrochemistry for relevant examples.

Step-by-Step Solution

Answer

Overall reaction:

\(2{\rm{LiCl}}({\rm{l}}) + electical{\rm{ }}energy \to 2{\rm{Li}}(s) + C{l_2}(g)\)

Step 1: Electrolysis of molten lithium chloride

The electrolysis cell has three phases:

• The molten salt mixture of LiCl-KCl as electrolyte, 
• The liquid lithium produced by the vertical cathode, and 
• The gaseous chlorine produced by the vertical anode.

Step 2: Balanced equations for the overall reaction in the electrolysis of molten lithium chloride

The overall reaction is:

\(2{\rm{LiCl}}({\rm{l}}) + electical{\rm{ }}energy \to 2{\rm{Li}}(s) + C{l_2}(g)\)

The reactions at cathode and anode are:

At the cathode \(:2L{i^ + } + 2{e^ - } \to 2Na(l)\)

At the anode:\(2C{l^ - } \to C{l_2}(g) + 2{e^ - }\)

The overall reaction is:

Overallchange:\({\bf{2L}}{{\bf{i}}^{\bf{ + }}}{\bf{ + 2C}}{{\bf{l}}^{\bf{ - }}} \to {\bf{2Na(l) + C}}{{\bf{l}}_{\bf{2}}}{\bf{(\;g)}}\)