Question

If the reaction of phosphate ion with water is ignored, what is the total concentration of ions in a solution prepared by dissolving 3.00 g of K3PO4 in enough water to make 350. mL of solution?
A) 0.162 M
B) 0.0404M
C) 0.323M
D) 0.0101 M

Answer 1

Answer:

A) 0.162 M

Explanation:

Calculation of the moles of $K_3PO_4$ as:-

Mass = 3.00 g

Molar mass of $K_3PO_4$ = 212.27 g/mol

The formula for the calculation of moles is shown below:

$moles = \frac{Mass\ taken}{Molar\ mass}$

Thus,

$Moles= \frac{3.00\ g}{212.27\ g/mol}$

$Moles= 0.01413\ mol$

$K_3PO_4$ will form ions as:-

$K_3PO_4\rightarrow 3K^++PO_4^{3-}$

Total number of ions = 3 + 1 = 4

Total moles = $4\times 0.01413\ mol=0.05652\ mol$

Volume = 350 mL = 0.35 L ( 1 mL = 0.001 L )

$Molarity=\frac{Moles\ of\ solute}{Volume\ of\ the\ solution}$

$Molarity=\frac{0.05652}{0.35}\ M=0.162\ M$

Total concentration of the ions - A) 0.162 M