Answer:
Option A. H₂O
Explanation:
PCl3 + 3H2O → H3PO3 + 3HCI
From the equation,
We can see clearly that for every 3moles of H2O, 1mole of PbCl3 is needed. This clearly indicates that H2O is the limiting reactant. This can further be proved by doing the following:
From the equation,
1mole of PbCl3 required 3moles of H20.
Therefore, 7moles of PbCl3 will require = 7x3 = 21moles of H2O. This amount(i.e 21moles) of H20 is far greater than what was given (i.e 5moles of H2O) from the question.
Now let us consider the reverse case as follows:
From the equation,
1mole of PbCl3 required 3moles of H20.
Therefore, Xmol of PbCl3 will require 5moles of H2O i.e
Xmol of PbCl3 = 5/3 = 1.67moles
This amount(i.e 1.67moles of PbCl3) obtained is smaller than what was given (i.e 7moles of PbCl3) from the question.
This shows that PbCl3 is excess and H20 is the limiting reactant
