Q74E - Chemistry (OpenStax)

Question

Write equations showing the stepwise ionization of phosphorous acid.

Step-by-Step Solution

Answer

Phosphorous acid, \({H_3}P{O_3}\) is a diprotic acid containing two protons that can be ionised.

Step 1: Definition of H 3 PO 3

• Phosphorous acid is a chemical substance with the formula H₃PO₃. 
• This acid is diprotic, not triprotic, as the formula might suggest. 
• Phosphorous acid is a chemical substance that is used to make other phosphorus compounds.

Step 2: Determine the ionization of phosphorous acid.

Phosphorous acid, \({H_3}P{O_3}\) is a diprotic acid that isn't very strong. The ionisation reactions that result from the loss of the two protons occur in a stepwise way, as shown below:

\(\begin{array}{l}{H_3}P{O_3} \leftrightarrow {H^ + } + {H_2}PO_3^ - \\{H_2}PO_3^ -  \leftrightarrow {H^ + } + HPO_3^{2 - }\end{array}\)

As a result, \({H_3}P{O_3}\)is a diprotic acid containing two ionisable protons.