Solid calcium carbonate and aqueous hydrogen phosphate will yield aqueous calcium phosphate, gaseous carbon dioxide, and liquid water?

2016-03-02 4:14 pm
a) If 25.5g of calcium carbonate reacts with excess hydrogen phosphate, how many grams of carbon dioxide will be produced?
b) Calculate the number of grams of water that will be produced when 35.7 g of calcium carbonate is reacted with excess hydrogen phosphate.
c) What mass of hydrogen phosphate will react with excess calcium carbonate to produce 45.9g of calcium phosphate?

回答 (1)

2016-03-02 4:35 pm
a)
Molar mass of CaCO₃ = 40.1 + 12.0 + 16.0×3 = 100.1 g/mol
Molar mass of CO₂ = 12.0 + 16.0×2 = 44.0 g/mol

3 CaCO₃ + 2 H₃PO₄ → Ca₃(PO₄)₂ + 3H₂O + 3CO₂
Mole ratio CaCO₃ : CO₂ = 1 : 1

No. of moles of CaCO₃ = 25.5/100.1 mol
No. of moles of CO₂ produced = 22.5/100.1 mol
Mass of CO₂ produced = 44 × (22.5/100.1) = 9.89 g


b)
Molar mass of CaCO₃ = 100.1 g/mol
Molar mass of H₂O = 1.0×2 + 16.0 = 18.0 g/mol

3 CaCO₃ + 2 H₃PO₄ → Ca₃(PO₄)₂ + 3H₂O + 3CO₂
Mole ratio CaCO₃ : H₂O = 1 : 1

No. of moles of CaCO₃ = 35.7/100.1 mol
No. of moles of H₂O produced = 35.7/100.1 mol
Mass of H₂O produced = 18 × (35.7/100.1) = 6.42 g


c)
Molar mass of Ca₃(PO₄)₂ = 40.1×3 + 31.0×2 + 16.0×8 = 310.3 g/mol
Molar mass of H₃PO₄ = 1.0×3 + 31.0 + 16.0×4 = 98.0 g/mol

3 CaCO₃ + 2 H₃PO₄ → Ca₃(PO₄)₂ + 3H₂O + 3CO₂
Mole ratio H₃PO₄ : Ca₃(PO₄)₂ = 2 : 1

No. of moles of Ca₃(PO₄)₂ produced = 45.9/310.3 mol
No. of moles of H₃PO₄ needed = (45.9/310.3) × 2 mol
Mass of H₃PO₄ needed = 98.0 × (45.9/310.3) × 2 = 29.0 g


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