Answer:
17.2mL
Explanation:
Step 1:
Determination of the molarity of potassium phosphate K3PO4 solution.
This is illustrated below:
Mass of K3PO4 = 46.3g
Molar Mass of K3PO4 = (39x3) + 31 + (16x4) = 212g/mol
Mole of K3PO4 =..?
Mole = Mass /Molar Mass
Mole of K3PO4 = 46.3/212 = 0.218 mole
Volume of water = 250mL = 250/1000 = 0.25L
Molarity = mole /Volume
Molarity of K3PO4 = 0.218/0.25
Molarity of K3PO4 = 0.872M
Step 2:
Determination of the volume of the stock solution of K3PO4 needed.
Molarity of stock solution (M1) = 0.872M
Volume of stock solution needed (V1) =..?
Molarity of diluted solution (M2) = 0.1M
Volume of diluted solution (V2) = 150mL
The volume of the stock solution needed can be obtained as follow:
M1V1 = M2V2
0.872 x V1 = 0.1 x 150
Divide both side by 0.872
V1 = (0.1 x 150)/0.872
V1 = 17.2mL
Therefore, the volume of the stock solution needed is 17.2mL
