Conversion of units for concentration: mol/l to ppm

The concentration of an aqueous solution of $\ce{Mg(SO4)2}$ is $0.001\, \textrm{mol} \cdot \textrm{dm}^{-3}$.


Find out the concentration of solution and the concentation of $\ce{Mg^{2+}}$ ion in *ppm*.


How to do this? How to find moles in ppm?


If anyone could clearly describe, it would be great. 




Convert mol-dm^2 to grams/volume. A decimeter is 10 cm. A dm^3 is then a liter. Water has density ~1 g/cm^3. Multiply the g(Mg)/g(water) by a million.


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