Question

You need to make an aqueous solution of 0.175 M potassium phosphate for an experiment in lab, using a 500 ml. volumetric flask. How much solid potassium phosphate should you add? Submit Answer Try Another Version 1 item attempt remaining

Answer 1

volume , V = 5*10^2 mL

= 0.5 L

use:

number of mol,

n = Molarity * Volume

= 0.175*0.5

= 8.75*10^-2 mol

Molar mass of K3PO4,

MM = 3*MM(K) + 1*MM(P) + 4*MM(O)

= 3*39.1 + 1*30.97 + 4*16.0

= 212.27 g/mol

use:

mass of K3PO4,

m = number of mol * molar mass

= 8.75*10^-2 mol * 2.123*10^2 g/mol

= 18.57 g

Answer: 18.6 g