What mass of lithium phosphate is needed to prepare 500. mL of a solution having a lithium ion concentration of 0.125 M?
A) 2.41 g
B) 7.24 g
C) 14.5 g
D) 21.7 g
E) 43.4 g

Question

Quizplus · Accepted Answer

The molar mass of lithium phosphate is 115.79 g/mol. The number of moles of lithium ions in 500. mL of a 0.125 M solution is:$$0.125 	ext{ mol/L} 	imes 0.500 	ext{ L} = 0.0625 	ext{ mol}$$The number of moles of lithium phosphate needed to provide this number of lithium ions is also 0.0625 mol. The mass of lithium phosphate needed is:$$0.0625 	ext{ mol} 	imes 115.79 	ext{ g/mol} = 7.24 	ext{ g}$$

What Mass of Lithium Phosphate Is Needed to Prepare 500