JEE Main · 2021 · Shift-ImediumPB12-070

The number of ionisable hydrogens present in the product obtained from a reaction of phosphorus trichloride and…

p-Block Elements (Class 12) · Class 12 · JEE Main Previous Year Question

Question

The number of ionisable hydrogens present in the product obtained from a reaction of phosphorus trichloride and phosphonic acid is:

Options
  1. a

    3

  2. b

    0

  3. c

    2

    ✓
  4. d

    1

Correct Answerc

2

Detailed Solution

Strategy: Identify the product formed from the dehydration reaction of phosphorus trichloride and phosphonic acid.

Step 1: Chemical Reaction Reaction between phosphorus trichloride (\cePCl3)(\ce{PCl3}) and phosphonic acid (also known as phosphorous acid, \ceH3PO3\ce{H3PO3}) results in the formation of pyrophosphorous acid: \cePCl3+5H3PO3→3H4P2O5+...\ce{PCl3 + 5H3PO3 \to 3H4P2O5 + ...} (Simplified stoichiometry) The product is Pyrophosphorous acid, \ceH4P2O5\ce{H4P2O5}.

Step 2: Ionisable Hydrogens The structure of pyrophosphorous acid is \ce(HO)HP(=O)−O−P(=O)H(OH)\ce{(HO)HP(=O)-O-P(=O)H(OH)}. It contains two \ceP−OH\ce{P-OH} groups and two \ceP−H\ce{P-H} groups. Only the protons attached to oxygen are ionisable (acidic). Thus, there are 2 ionisable hydrogens.

Answer: (Option) [c] 2\boxed{\text{Answer: (Option) [c] 2}}

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