Ncert Exercises & Solutions

6.24 Name the processes from which chlorine is obtained as a by-product. What will happen if an aqueous solution of NaCl is subjected to electrolysis?

In the electrolysis of molten NaCl,

C L_{2}

is obtained at the anode as a by product.

N a C L_{(m e l t)} \to N {a^{+}}_{(m e l t)} + C {L^{-}}_{(m e l t)}

A t c a t h o d e : N {a^{+}}_{(m e l t)} + e^{-} \to N a_{(s)}

A t a n o d e : C {l^{-}}_{(m e l t)} \to C l_{(g)} + e^{-}

2 C L_{(g)} \to C l_{2 (g)}

T h e o v e r a l l r e a c t i o n i s a s f o l l o w s :

N a C L_{(m e l t)} \overset{E l e c t r o l y s i s}{\to} N a_{(s)} + \frac{1}{2} C l_{2 (g)}

If an aqueous solution of NaCl is electrolyzed,

C l_{2}

will be obtained at the anode but at the cathode,

H_{2}

will be obtained (instead of Na). This is because the standard reduction potential of Na (E°= − 2.71 V) is more negative than that of

H_{2} O

(E° = − 0.83 V). Hence,

H_{2} O

will get preference to get reduced at the cathode and as a result,

H_{2}

is evolved.

N a C L_{(a q)} \to N {a^{+}}_{(a q)} + C {L^{-}}_{(a q)}

A t c a t h o d e : 2 H_{2} O_{(l)} + 2 e^{-} \to H_{2 (g)} + 2 O H_{(a q)}^{-}

A t a n o d e : C {l^{-}}_{(m e l t)} \to C l_{(g)} + e^{-}

2 C L_{(g)} \to C l_{2 (g)}

NEET Information

courses

Company

Botany Questions

Chemistry Questions

Physics Questions

Zoology Questions