Calculate the mass (in grams) of calcium carbonate present in a 50.00 mL sample of an aqueous calcium carbonate standard, assuming the standard is known to have a hardness of 75.0 ppm (hardness due to CaCO3).

The units of ppm means parts per million. Also, It is equivalent to milligrams per liter. It is one way of expressing concentration of a substance. It u sually used to describe the concentration of something in water or soil. We calculate the mass of CaCO3 as follows:

Mass = 75 mg/L (.050 L) = 3.75 mg CaCO3