Question

How many grams of calcium phosphate can be produced when 78.5 grams of calcium hydroxide reacts with excess phosphoric acid? Unbalanced equation: H3PO4 + Ca(OH)2 → H2O + Ca3(PO4)2 Show, or explain, all of your work along with the final answer.

Answer 1

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Answer 2

The balanced chemical equation is written as :
2H3PO4 + 3Ca(OH)2 → 6H2O + Ca3(PO4)2.
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From the above equation we can see that 3 moles of Ca(OH)2 produces 1 mole Ca3(PO4)2 .
( Don't take tension about H3PO4 as it is present in excess )
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Further ,
we are given 78.5 g Ca(OH)2 .
then no of moles Ca(OH)2 given = 78.5/74 = 1.06 moles.
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3 moles Ca(OH)2 produces → 1 mole Ca3(PO4)2.
=> 1 mole Ca(OH)2 produces → 1/3 mole Ca3(PO4)2.
=> 1.06 mole Ca(OH)2 produces → (1/3)×1.06 mole Ca3(PO4)2.
Hence number of moles Ca3(PO4)2 produced = (1/3)×1.06 = 0.353 moles.
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Now gram molecular mass of Ca3(PO4)2 is = 310 g /mole .
hence grams of Ca3(PO4)2 produced
= 0.353× 310 = 109.43 g
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