1. The problem statement, all variables and given/known data If one leads chloride gas over salty water with a density of 1,1kg/L containing 4700ppm Bromide (Br-) then the bromide shall react with the chloride gas. How much chloride gas does one need to produce 1kg of Br2? 2. Relevant equations The reaction is 2Br- + Cl2 --> Br2 + 2Cl-.. not really relevant, I think 3. The attempt at a solution I think we can safely assume that the average molar mass of the water is ~ 19grams maybe , and thus the molar density is (1,1kg/19gramspermole)L = ~ 59 moles/L Br- concentration is 4,7 parts per thousand molecules. So concentration of Br- is 59*4,7*10^-3 moles/L = 0,2773moles/L. We needed 1Kg of Br2/Br-, with the molar mass of Br being 80g/mole. 1kg/80g/mole = 12,5 moles. 12,5 moles/0,2773 moles= 45. We need 45L of salty water to produce 1Kg of Br2, in theory. But the correct answer is 192L.. What am I doing wrong?