What mass of lithium phosphate is needed to prepare 500. ml of a solution having a lithium ion concentration of 0.125 m?

First, we must calculate the moles of lithium ions required using:

Concentration = moles / liter

500 ml = 0.5 L

0.125 = moles / 0.5

moles = 0.0625

Lithium phosphate has the formula Li₃PO₄, meaning each mole of lithium phosphate releases three moles of lithium ions. The moles of lithium phosphate required will be:

0.0625 / 3 = 0.021 mol

The mass of one mole of lithium phosphate is 116 g/mol

Mass of lithium phosphate required = 0.021 x 116

Mass of lithium phosphate required = 2.42 grams