What is the mass of a cubic centimeter of pure water?
It is one gram.
1g, since one liter of pure water has a mass of 1kg = 1000g, and a volume of 1000cm3.
The volume measure of a cup is 236,58823658 milliliter or 236,5882368 cubic centimeter. The volume measure of half a cup is 118,294118 milliliter or 118,294118 cubic centimeter. Only if you think of pure water, you can say: 1 milliliter weighs 1 gram. Half a cup of pure water weighs 118,294118 grams.