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 750. mL of a solution that has a concentration of Na+ ions of 1.00 M ?

Express your answer to three significant figures and include the appropriate units.

Answer 1

Let; we have;

[Na⁺] =1.00M

Volume of solution =750. mL = 0.750L

Calculating the number of moles of Na⁺ ions from the given data;

Number of moles of Na⁺ ions = Molarity x Volume(L)

= 1.00M x 0.750L

Number of moles of Na⁺ ions = 0.75 moles of Na⁺ ions

Now; 1 mole of Na₃PO₄ = 3 moles of Na⁺ ions

So, 0.75 moles of Na⁺ ions x( 1 mole of Na₃PO₄/3moles of Na⁺ ions) = 0.25 moles of Na₃PO₄

Now; converting these moles of Na₃PO₄ to grams;

0.25 moles of Na₃PO₄ x(163.94g/1mole) =40.985 g of Na₃PO₄

So, 41.0g OR 40.9g Na₃PO₄ will be needed to produce 750.0mL of a solution that has a concentration of Na⁺ ion of 1.00M.