Question

One drop of methyl orange solution when added to the solution obtained after electrolysis of a concentrated solution of $NaCl$ with $P^{+}$ electrodes, the colour of the solution will turn:

• A. orange
• B. pink
• C. yellow
• D. colourless

Answer 1

The correct option is C yellow

$NaCl\to N{a}^{+}+C{l}^{-}$

$H_{2}O\to H^{+}+O{H}^{-}$

At cathode $2H^{+}+2e\to H_2$

At anode $2O{H}^{-}\to H_{2}O+\frac{1}{2}{O}_2+2e^{-}$

At medium NaOH will be present and pH > 7

Methyl orange shows red color in acidic medium and yellow color in basic medium. Because it changes color at the pH of a mid-strength acid, it is usually used in titration for acids.

So, the colour of the solution will turn yellow.