Question

Formation of super phosphate is:

• A. exothermic reaction
• B. endothermic reaction
• C. reversible reaction
• D. none of the above

Answer 1

The correct option is A exothermic reaction

A well powdered phosphate rock or bone ash mixed known quantity of concentrate sulphuric acid is introduced into a cast iron chamber provided with mechanical stirrer and two valves at bottom. Each valve opens in a big chamber called den. The mixture is stirred for 2 to 5 minutes and then dumped mechanically into one of the dens through the valve. The mass is kept in the den for about 24 hours.

${Ca}_3{\left(P{O}_4\right)}_2+2H_{2}S{O}_4+4H_{2}O⟶Ca{\left(H_{2}P{O}_4\right)}_2+2CaS{O}_4.2H_{2}O+Heat$

A mixture of calcium sulphate and calcium dihydrogen phosphate is obtained .This mixture is called superphosphate.