In: Chemistry
Q4. If 77.00 mL of 1.655 M magnesium sulfate solution is combined with 85.00 mL of 1.294 M sodium phosphate solution, and 7.647 g of precipitate is recovered, what is the percent yield?
3MgSO4 + 2Na3PO4 -------> Mg3(PO4)2 + 3Na2SO4
Stoichiometric mass of MgSO4 = 3×120.366g = 361.098g
Stoichiometric mass of Na3PO4 = 2 × 163.94g = 327.88g
Stoichiometric mass of Mg3(PO4)2=1 × 262.857g = 262.857g
given mass of MgSO4 = ((1.655mol/1000ml)×77ml)×120.366g = 15.3388g
given mass of Na3PO4 = (1.294mol/1000ml)×85ml = 18.0317g
stoichiometrically 361.098g of MgSO4 require 327.88g of Na3PO4
Therefore, 15.3388g of MgSO4 require (327.88/361.098)×15.3388g = 13.9277g of Na3PO4
but actual mass of Na3PO4 is 18.0317g
So, MgSO4 is limiting
361.098g of MgSO4 give 262.857g of Mg3(PO4)2
Therefore, 15.3388g of MgSO4 give
(262.857/361.098)×15.3388g = 11.1656g of Mg3(PO4)2
Actual yield = 7.647g
Percent yield =( actual yield / theoretical yield)×100
= (7.647g/11.1657g)×100
= 68.49℅