The Brisbane City Council classifies Brisbane drinking water as moderately soft, with an average hardness of one millimole/litre CaCO3. What is this concentration in ppm?
g = mols x molar mass
g = 0.001 x 100 = 0.1 gram/L
That is 100 mg/L which is 1 ppm = 1 mg/L so 100 mg/L = 100 ppm.