Chemistry Help

Question

Impure phosphoric acid for use in the manufacture
of fertilizers is produced by the reaction
of sulfuric acid on phosphate rock, of
which a principal component is Ca3(PO4)2.
The reaction is
Ca3(PO4)2(s) + 3 H2SO4(aq) →
3 CaSO4(s) + 2 H3PO4(aq)

 

005 How many moles of H3PO4 can be produced
from the reaction of 154.2 kg of H2SO4?

Answer in units of mol.

006 (part 2 of 2) 10.0 points
What mass of calcium sulfate is produced
as a by-product of the reaction of 143.7 mol
Ca3(PO4)2?
Answer in units of g.

Answer 1

n - # of moles; m - mass; M_w - molecular weight.

 

005:

n_H3PO4/2 = n_H2SO4/3 ; n_H3PO4 = n_H2SO4*(2/3) ; n_H2SO4 = m/M_w = 154,200g / 98.08g/mol = 1,572 mol

n_H3PO4 = n_H2SO4*(2/3) = 1,572 *(2/3) = 1,048 mol

 

006:

 

 

n_CaSO4/3 = n_Ca3(PO4)2/1 ; n_CaSO4 = 3*n_Ca3(PO4)2 = 3*143.7 = 431.1 mol

 

m_CaSO4 = n_CaSO4*M_wCaSO4 =  431.1mol*136.14g/mol = 58,690 g