Biology (or basic Chemistry question): a recipe is given to make 1l of PBS (phosphate buffered saline), which includes 800ml of water and 80g of NaCl....

Biology (or basic Chemistry question): a recipe is given to make 1l of PBS (phosphate buffered saline), which includes 800ml of water and 80g of NaCl. I need to find molar concentration of NaCl in that solution. Molecular mass on NaCl is 58.44g/mol.

Is molar concentration meant to be calculated based on 1l solution OR 1l of water?