Hi, I've just completed one question and I wish to know I've done it correctly;
Thank you in advance for your time to view this post.
Q. Magnesium hydroxide reacts with phosphoric acid to produce magnesium phosphate and water. Find the mass of magnesium hydroxide that will react with 38.2g of acid.
Here is my attempt.
Mg(OH)2 + H3PO4 -----> Mg3(PO4)2 + H2O
Balancing equation;
3Mg(OH)2 + 2H3PO4 -----> Mg3(PO4)2 + 6H2O
2H3PO4 : 3Mg(OH)2
2 mol : 3 mol
molar mass of H3PO4 = 98.0 g/mol
moles of H3PO4 = 38.2 g / 98.0 g/mol = 0.390 mol
Let x=mol of Mg(OH)2
0.390mol x mol
2H3PO4 ----> 3Mg(OH4)2
2mol 3mol
0.390/2 = x/3
x = 0.5850 mol
Molar mass of Mg(OH)2 = 58.0 g/mol
mass of Mg(OH)2 produced;
= 0.5850 mol X 58.0 g/mol
= 33.9 g
Therefore the mass of Mg(OH)2 that will react is 33.9 g