Question

A scientist wants to make a solution of tribasic sodium phosphate, Na3PO4, for a laboratory experiment. How many grams of Na3PO4 will be needed to produce 600mL of a solution that has a concentration of Na+ ions of 0.500M ? Express your answer to three significant figures and include the appropriate units.

Answer 1

Given

Na3P04

Na3P04 ---> 3 Na+ + P043-

from the above reaction

[Na+] = 3 x [Na3P04]

given

[Na+] = 0.5 M

so

0.5 = 3 x [Na3P04]

[Na3P04] = 0.16666 M

we know that

molarity = moles / volume (L)

so

0.1666 = moles / 0.6

moles = 0.1

moles of Na3P04 = 0.1

now

mass = moles x molar mass

so

mass of Na3P04 = 0.1 x 163.94

mass of Na3P04 = 16.39 g

so

mass of Na3P04 required is 16.4 g