A scientist wants to make a solution of tribasic sodium phosphate?

Question

A scientist wants to make a solution of tribasic sodium phosphate, Na3PO4Na3PO4, for a laboratory experiment. How many grams of Na3PO4Na3PO4 will be needed to produce 525 mLmL of a solution that has a concentration of Na+Na+ ions of 1.50 MM ?

Answer 1

molar mass Na₃PO₄ = 164 g / mol

Volume = 525 ml x 1 L / 1000 mls = 0.525 L

[Na⁺] = 1.50 M = 1.50 mol / L

mols Na⁺ = 1.50 mol / L x 0.525 L = 0.7875 mols Na⁺

Since you have 3 mols Na⁺ for each mol of Na₃PO₄, the mass of Na₃PO₄ can be found as follows:

0.7875 mol Na⁺ / L x 1 mol Na₃PO₄ / 3 mol Na⁺ x 164 g Na₃PO₄/mol Na₃PO₄ = 43.1 g Na₃PO₄ needed