Question

What is the super-phosphate of lime?

Answer 1

• The mixture of calcium dihydrogen phosphate and calcium sulfate (gypsum) is called superphosphate of lime.
• Superphosphate of lime is a necessary fertilizer, obtained from the action of sulphuric acid on phosphate rock.
• By knowing the products of the reaction of sulphuric acid and phosphate rock, we can determine the composition of superphosphate.
• As it is a mixture, it will contain more than one compound.

Preparation of super-phosphate of lime:

${\mathrm{Ca}}_3{\left({\mathrm{PO}}_4\right)}_2\left(\mathrm{s}\right)+{\mathrm{H}}_2{\mathrm{SO}}_4\left(\mathrm{l}\right)+4{\mathrm{H}}_2\mathrm{O}\left(\mathrm{l}\right)\to 2{\mathrm{CaSO}}_4.2{\mathrm{H}}_2\mathrm{O}\left(\mathrm{aq}\right)+2{\left({\mathrm{CaH}}_2{\mathrm{PO}}_4\right)}_2\left(\mathrm{aq}\right)$

Calcium Sulphuric Water Calcium Calcium dihydrogen

phosphate acid sulfate phosphate