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1- Phosphoric acid is used as a commercial fertilizer and fungicide to treat avo

ID: 901748 • Letter: 1

Question

1- Phosphoric acid is used as a commercial fertilizer and fungicide to treat avocado crops in California, with a coverage rate of 2.50 g/m2. Phosphoric acid can be produced by the reaction between sulfuric acid and calcium phosphate, represented by the unbalanced equation written below. (20 points)

a3(PO4)2 + 3H2SO4 à 2H3PO4 +     CaSO4

A farmer with a 12,200m^2 avocado farm wants to produce enough phosphoric acid to treat his crop.

a) He combines 39.5 kg calcium phosphate with 40.6 kg sulfuric acid. Which will be the limiting reagent?

b) How much of the excess reagent (in g) will be left over?

c0 Will the farmer produce enough phosporic acid to cover his avocado field?

Explanation / Answer

Ca3(PO4)2   + 3H2SO4 ----> 2H3PO4   +     CaSO4

amount of H3PO4 required = 12200*2.5 = 30500 grams = 30.5 kg

a) molarmas of Ca3(PO4)2 = 310.18 g/mol

No of moles of Ca3(PO4)2 = 39.5*10^3/310.18 = 127.345 mole.

molarmas of H2SO4 = 98 g/mol

No of moles of H2SO4 = 40.6*10^3/98 = 414.29 mole.

limiting reagent is Ca3(PO4)2

b) excess reagent = H2SO4

no of moles of excess H2SO4 = 414.29-382.035 = 32.255 mole.

mass of excess H2SO4 = 32.255*98 = 3160.99 grams = 3.161 kg

c) amount of H3PO4 produced = 127.345*2*98 = 24959.62 grams

                 = 24.960 kg

so that, produced H3PO4 is lesser than required.