To determine which electrolyte can be used to obtain \( \text{H}_2\text{S}_2\text{O}_8 \) (peroxydisulfuric acid) by the process of electrolysis, we need to understand the conditions required for its formation:
1. Principle of Electrolysis: Electrolysis involves the decomposition of compounds using an electric current. The electrolyte's nature significantly affects the products formed.
2. Peroxydisulfuric Acid Formation: This compound is specifically formed when concentrated sulfuric acid is electrolyzed. The equation for the formation of \( \text{H}_2\text{S}_2\text{O}_8 \) is as follows:
2 \( \text{HSO}_4^- \) (aq) → \( \text{H}_2\text{S}_2\text{O}_8 \) (aq) + 2 \( e^- \)
3. Options Analysis:
Option | Suitability |
Dilute solution of sodium sulphate | Not suitable, lacks sufficient sulfate ions and concentration. |
Dilute solution of sulphuric acid | Not suitable due to low concentration. |
Concentrated solution of sulphuric acid | Suitable; provides high concentration of sulfate ions for forming \( \text{H}_2\text{S}_2\text{O}_8 \). |
Acidified dilute solution of sodium sulphate | Not suitable, lacks adequate concentration of \( \text{HSO}_4^- \) ions. |
The process's efficiency in forming \( \text{H}_2\text{S}_2\text{O}_8 \) increases with the concentration of \( \text{HSO}_4^- \) ions provided by concentrated sulfuric acid, which makes it the correct choice.
For the thermal decomposition of \( N_2O_5(g) \) at constant volume, the following table can be formed, for the reaction mentioned below: \[ 2 N_2O_5(g) \rightarrow 2 N_2O_4(g) + O_2(g) \] Given: Rate constant for the reaction is \( 4.606 \times 10^{-2} \text{ s}^{-1} \).
Let \( T_r \) be the \( r^{\text{th}} \) term of an A.P. If for some \( m \), \( T_m = \dfrac{1}{25} \), \( T_{25} = \dfrac{1}{20} \), and \( \displaystyle\sum_{r=1}^{25} T_r = 13 \), then \( 5m \displaystyle\sum_{r=m}^{2m} T_r \) is equal to: