How many grams of sodium chloride would be made if 507 g FeCl2 were used up in the reaction FeCl2 + 2NaOH Fe(OH)2(s) + 2NaCl, ?
The 200 mL sample of a natural water contains Ca in it and this was determined by precipitating the cation as Calcium oxalate(CaC2O4). This precipitate was filtered, washed and ignited in a crucible with an empty mass= 26.6002 grams, The mass of the crucible plus CaO (M.W 56.077 g/mol) = 26.7134 g. now just calculate the concentration of Calcium (MW 40.078 g/mol) in the H2O in units of gram per 100 mL.