A volt-equivalent diagram is essentially a plot of free energy versus oxidation state. Two further points follows from these general considerations: (a) A compound will tend to disproportionate into a higher and lower oxidation state if it lies above the line joining the 2 compounds in these oxidation state. (b) Conversely, a compound can be formed by comproportionation of different compounds in which the element has a higher and lower oxidation state if it lies below the line joining these two. (i) Volt equivalent diagram of compound or ions containing nitrogen in acidic aqueous medium. (ii) Volt equivalent diagram of compound or ions containing phosphorus in acidic aqueous medium.

A volt-equivalent diagram is essentially a plot of free energy versus oxidation state. Two further points follows from these general considerations:

(a) A compound will tend to disproportionate into a higher and lower oxidation state if it lies above the line joining the 2 compounds in these oxidation state.

(b) Conversely, a compound can be formed by comproportionation of different compounds in which the element has a higher and lower oxidation state if it lies below the line joining these two.

(i) Volt equivalent diagram of compound or ions containing nitrogen in acidic aqueous medium.

(ii) Volt equivalent diagram of compound or ions containing phosphorus in acidic aqueous medium.

Linked Question 1

Synthesis of HN₃ is done in acidic aqueous solution by reacting:

NH₄⁺ & N₂

N₂H₅⁺ & N₂

NH₃OH⁺ & N₂

N₂H₅⁺ & HNO₂

N₂H₅⁺ + HNO₂ $\to_{}^{}$ HN₃

HN₃ is synthesised by comproportionation of N₂H₅⁺ & HNO₂ as HN₃ lies below line joining N₂H₅⁺ & HNO₂.

Linked Question 2

Select correct statement :

H₃PO₄ is better oxidising agent because it has lowest value of $∆$ G among other species of phosphorus

Oxidising nature in acidic aqueous solution of H₃PO₄ > HNO₃

H₃PO₄ is better reducing agent because it has lowest value of $∆$ G among other species of phosphorus

HNO₃ is better oxidising agent because it has highest value of $∆$ G among other species of nitrogen

NH₃OH⁺ $\to_{}^{}$ N₂O + NH₄⁺

NH₃OH⁺ disproportionates to form N₂O and NH₄⁺ as NH₃OH⁺ lies above line joining N₂O and NH₄⁺.

Linked Question 3

Which of the following will decompose to form N₂O and NH₄⁺ in acidic aqueous solution:

N₂

HNO₂

H₂N₂O₂

NH₃OH⁺

NH₃OH⁺ $\to_{}^{}$ N₂O + NH₄⁺

NH₃OH⁺ disproportionates to form N₂O and NH₄⁺ as NH₃OH+ lies above line joining N₂O and NH₄⁺.