Question

10.30 mg of $O_2$ dissolved into a litre of sea water of density 1.03g/mL. The concentration of $O_2$ in ppm is

Answer 1

$\text{ppm}=\frac{W_{\text{Solute}}}{W_{\text{Solution}}}\times 100$
Using the density of the solution and its volume $(1\text{L}=1000\text{mL}=1000{\text{cm}}^3)$, the weight of the solution can be calculated.
$W_{\text{solution}}=1.03\times 1000=1030\text{g}$
Thus, ppm $\frac{10.3\times {10}^{-3}\text{g}}{1030\text{g}}\times {10}^6=10ppm$