When Na3PO4 and Ca(NO3)2 are combined, the following reaction occurs: 2PO4 + 3Ca -> Ca3(PO4)2?

2017-10-24 6:36 pm

When Na3PO4 and Ca(NO3)2 are combined, the following reaction occurs: 2PO4 + 3Ca -> Ca3(PO4)2?
How many grams of Ca3(PO4)2 (s) (MM = 310.18 g/mol) are obtained when 15.00ml of 0.1386 M Na3PO4 are mixed with 20.00 mL of 0.2118 M Ca(NO3)2.
please explain by using the formula given, I have the answer I just don't know how to get to it

回答 (1)

胡雪8°

2017-10-24 7:52 pm

✔ 最佳答案

Initial number of moles of Na₃PO₄ = (0.1386 mol/L) × (15.00/1000) = 0.002079 mol
Initial number of moles of Ca(NO₃)₂ = (0.2118 mol/L) × (20.00/1000) = 0.004236 mol

Complete equation for the reaction :
2Na₃PO₄ + 3Ca(NO₃)₂ → Ca₃(PO₄)₂ + 6NaNO₃
Mole ratio Na₃PO₄ : Ca(NO₃)₂ = 2 : 3
When Na₃PO₄ completely reacts, Ca(NO₃)₂ needed = (0.002079 mol) × (3/2) = 0.l003119 mol < 0.004236 mol
Hence, Ca(NO₃)₂ is in excess, and Na₃PO₄ completely reacts (limiting reactant/reagent).

According to the above equation, mole ratio Na₃PO₄ : Ca₃(PO₄)₂ = 2 : 1
Number of moles of Ca₃(PO₄)₂ produced = (0.002079 mol) × (1/2) = 0.0010395 mol
Mass of Ca₃(PO₄)₂ produced = (0.0010395 mol) × (310.18 g/mol) = 0.3224 g

👍 2 👎 0