Statement 1 o-Hydroxy benzene sulphonic acid on heating to \(373 \mathrm{~K}\) changes to p-Hydroxybenzene sulphonic acid. and Statement 2 Sulphonation of phenol is a reversible process.

The given exercise states that o-Hydroxybenzene sulphonic acid, when heated to 373 K, changes to p-Hydroxybenzene sulphonic acid. This is because the sulphonation of phenol is highly temperature sensitive. Step 1: Write the reaction of sulphonation of phenol with sulfuric acid \[C_6H_5OH + H_2SO_4 \rightarrow C_6H_5OHSO_3H + H_2O\] Step 2: Indicate the positions of o-Hydroxybenzene sulphonic acid (ortho position) and p-Hydroxybenzene sulphonic acid (para position) Ortho position: -OHSO_3H group is attached to the carbon atom adjacent to the -OH group. Para position: -OHSO_3H group is attached to the carbon atom opposite to the -OH group. Step 3: State the reason for the conversion at 373 K At high temperatures, sterics become less important, and the preferred product is p-Hydroxybenzene sulphonic acid due to its higher stability compared to the o-Hydroxybenzene sulphonic acid.

The sulphonation of phenol is a reversible process, which means it can go back to its reactant form. This is because the reaction proceeds via a protonated phenol intermediate that can be attacked by water to give phenol. Step 1: Write the forward and reverse reactions \[C_6H_5OH + H_2SO_4 \rightleftharpoons C_6H_5OHSO_3H + H_2O\] Step 2: Describe the intermediate formation - Protonated phenol intermediate is formed when sulfuric acid protonates the phenol: \(C_6H_5OH + H_2SO_4 \rightarrow C_6H_5OH_2^+ + HSO_4^-\). - The protonated phenol intermediate can be attacked by the bisulfate ion to give o/p-Hydroxybenzene sulphonic acids: \(C_6H_5OH_2^+ \rightarrow C_6H_5OHSO_3H\). Step 3: Explain the reversibility using the intermediate - The intermediate protonated phenol can accept a water molecule and form phenol again by reversing the reaction: \(C_6H_5OH_2^+ + H_2O \rightarrow C_6H_5OH + H_3O^+\) - This reversibility of the reaction allows the equilibrium in the system and depends on the concentration and reaction conditions. In conclusion, we analyzed the conversion of o-Hydroxybenzene sulphonic acid to p-Hydroxybenzene sulphonic acid at 373 K and explained why the sulphonation of phenol is a reversible process.