Question

A solution is made by dissolving 74.5 g KNO3 in water to make 700.0 mL of solution. What is the molarity of the solution?

Answer 1

Answer:1.04M

Explanation:

Molarity is defined as the ratio of number of moles of solute per litre of solution.

Let molarity be $M$.

Given mass of $KNO_{3}$$=74.5g$

Weight of $K$ is $39g$

Weight of $N$ is $14g$

Weight of $O$ is $16g$

Molar mass of $KNO_{3}=39+14+3(16)=101g$

Let $n$ be the number of moles of solute.

$n=\frac{given mass}{molar mass}=\frac{74.5}{101}=0.73$

Let $v$ be the volume of solution.

Given,$v=700mL=0.7L$

$M=\frac{n}{v}$$=\frac{0.73}{0.7}=1.04M$