Question

Describe the two color changes which take place when moist Blue litmus is placed in a gas jar of chlorine.

Answer 1

• Litmus Paper- It is a type of paper that when dipped in an acidic solution then it changes color in response to the acidity of the solution and thus it can be used to measure acidity.
• When moist Blue litmus is placed in a gas jar of chlorine then the blue litmus turns red.
• This is because Chlorine reacts with water in the litmus papers to form acidic Hydrochloric acid$\left(\mathrm{HCl}\right)$ and Chloric acid $\left(\mathrm{HOCl}\right)$. Due to the formation of Hydrochloric acid blue litmus paper turns to red.
• $$\begin{gathered} {{\mathrm{Cl}}_2}_{\left(\mathrm{l}\right)}+{\mathrm{H}}_2{\mathrm{O}}_{\left(\mathrm{aq}\right)}\to {\mathrm{HOCl}}_{\left(\mathrm{aq}\right)}+{\mathrm{HCl}}_{\left(\mathrm{aq}\right)} \\ {\mathrm{HCl}}_{\left(\mathrm{aq}\right)}+{\mathrm{H}}_2{\mathrm{O}}_{\left(\mathrm{l}\right)}\to \underset{(\mathrm{Hydronium}\mathrm{ion})}{{\mathrm{H}}_3{{\mathrm{O}}^{+}}_{\left(\mathrm{aq}\right)}}+{{\mathrm{Cl}}^{-}}_{\left(\mathrm{aq}\right)} \end{gathered}$$