Question

What is the molarity of $KN{O}_3$ in a solution prepared by dissolving 3.75 g of $KN{O}_3$ in water to make a 375 mL solution?
(Molar mass of $KN{O}_3$ = 101 g/mol)

• A. 0.3 M
• B. 0.2 M
• C. 0.5 M
• D. 0.1 M

Answer 1

The correct option is D 0.1 M

$\text{Number of moles of}KN{O}_3=\frac{\text{given mass of}KN{O}_3}{\text{molar mass}}=\frac{3.75}{101}$

$\text{Molarity}=\frac{\text{number of moles of solute}}{\text{volume of solution in mL}}\times 1000$

$\text{Molarity}=\frac{\frac{3.75}{101}}{375}\times 1000=0.099M\approx 0.1M$