You collected a water sample from your shower containing (3.2 mM Ca2+)+(1.1 Mm Mg2+). Express the hardness of water in terms of mg CaCO3/L. (FM for CaCO3+100.09) I have no idea how to do this problem. Can anyone show me a step by step on how to work through it?

Answer 1

assuming your sample was 1L,
3.2mM Ca implies 3.2mmoles of CaCO3.
So, that's .0032*100.09 = 0.32g/L

Answer 2

I believe the hardness is the sum of the Ca and Mg ions.