A scientist wants to make a solution of tribasic sodium phosphate, Na_3PO_4, for a laboratory experiment. How many grams of Na_3PO_4 will be needed to produce 550 mL of a solution that has a concentration of Na^+ ions of 0.500 it M?

Answer 1

You want 0.5 M in Na^+. That will be 0.5/3 in Na3PO4.
M = moles/L soln
Substitute M and L and solve for moles.
moles Na3PO4 = grams/molar mass.
Solve for grams.

Answer 2

163.97