Q.

Consider the following reaction:

3PbCl2+2(NH4)3PO4Pb3(PO4)2+6NH4Cl

If 72 mmol of PbCl2 is mixed with 50 mmol of (NH4)3PO4, then the amount of Pb3(PO4)2 formed is _______ mmol (nearest integer).          [2024]


Ans.

(24)            3PbCl2+2(NH4)3PO4Pb3(PO4)2+6NH4Cl

                  Finding limiting reagent:

                  nPbCl2Stoichiometric coefficient of PbCl2=723=24

                 n(NH4)3PO4Stoichiometric coefficient of (NH4)3PO4=502=25

                  As 24 < 25, PbCl2 is limiting reagent. Amount of product i.e. Pb3(PO4)2 formed depends upon amount of limiting reagent i.e. PbCl2:

                 By stoichiometry:

                 nPb3(PO4)21=nPbCl23

                  nPb3(PO4)21=72 mmol3

                  nPb3(PO4)2=24 mmol