Calculate the % composition (by mass) of Mg in Mg3(AsO4)2?

1 Answer
Mar 18, 2015

You simply divide the molar mass of three magnesium atoms, the number of magnesium atoms you have in the compound, by the total molar mass of the compound and multiply by 100.

#(3 * "24.3050 g/mol")/"350.7594 g/mol" * 100 = "20.8%"#

This means that you get 20.8 g of magnesium for every 100 g of magnesium arsenate.