Question

How many moles of potassium ions are present in 2.50 L of 0.200 M potassium sulfate?

• A. 0.0800 mol
• B. 0.160 mol
• C. 0.400 mol
• D. 0.500 mol
• E. 1.00 mol

Answer 1

The correct option is E 1.00 mol

$K_{2}S{O}_4$ $\to$ $2K^{+}$ $+$ $S{O}_4^{2-}$. Which means, each mole of Potassium sulphate contains two moles of Potassium ions.

From molarity we can say:

$1L$ of $1M$ $K_{2}S{O}_4$ contains $2$ moles of Potassium ions.

$2.5L$ of $1M$ $K_{2}S{O}_4$ contains ($2$ $\times$ $2.5$) that is $5$ moles of Potassium ions.

Thus, $2.5L$ of $0.200M$ $K_{2}S{O}_4$ contains ($2$ $\times$ $2.5$ $\times$ $0.200$) that is $1$ mole of Potassium ions

Option $E$ is the correct answer.