Question

You’ve just started a new job in the laboratory of the Food and Drug Administration. Your supervisor asks you to prepare a 1.50-M solution of aqueous potassium permanganate, KMnO4. What mass of KMnO4 will you need to prepare 500 mL of this solution?

Answer 1

Answer:  118.5 grams

Explanation:

Molarity is defined as the number of moles of solute dissolved per liter of the solution.

$Molarity=\frac{n\times 1000}{V_s}$

where,

n= moles of solute

$V_s$ = volume of solution in ml = 500 ml

$1.50=\frac{moles\times 1000}{500ml}$

moles = 0.75

moles of solute =$\frac{\text {given mass}}{\text {molar mass}}$

0.75 =$\frac{\text {given mass}}{158g/mol}$

mass of $KMnO_4$ = 118.5 grams

Thus mass of $KMnO_4$ needed to prepare 500 mL of this solution iis 118.5 grams