Question

A solution was prepared by dissolving $5.76$ g of $KCl.MgC{l}_2.6H_{2}O$ in sufficient water to give $2.0$ L solution. Calculate the concentration of $K^{+}$ ion in ppm.

Answer 1

$5.76$ g of $KCl.MgC{l}_2.6H_{2}O$ are present in $2$ L solution.
This corresponds to $\frac{5.76}{277.5}$ mol in $2$ L solution.
Hence, the molarity of the solution is $0.01M$.
The molar analytical concentration of $KCl.MgC{l}_2$ is $0.01M$.
The molar concentration of $M{g}^{2+}$ ion is $0.01M$.
The molar concentration of chloride ion is $3\times 0.01=0.03M$
The concentration of potassium ion is $0.01M$.
This corresponds to $0.39$ g/L which is equal to $\frac{0.39}{1000}\times {10}^6$ parts per million or $390$ ppm.