Question

2. (12 points). You need to soften a water that has high concentrations of dissolved calcium and magnesium. (a) You measure the Cat concentration as 55 mg/L and the Mg concentration as 10 mg/L. What are these concentrations in units of mM?

Answer 1

cat: ssmg) like Magh so mall in terms of Molar concentration, - Molarity - moles volume of soll in litre moles of cott - soxd3 gm Yo Mular mais com mela M: 551703 moles of Mol. 1oxlu Hox1 40x140 55 MM M: loxio 24312 MM = 1.55 MM 20.4166 MM 6) To Remore ca as Caco and might as Marom we need to add Na coz and Caconha. - Nąco is used to treat non carbonate hardness while Cacono i used to treat carbonate hardness. in the Question, hardness is due to carbonate species thus Cacom) is Reagent of Choice here. Reactions indredi CACHCO) + Calon -> 2 Caco +2440 MyCac) + Cncom Cacg + Mg Co +240 2 Mg CC + 20.Com - l cace + Mycom) + 940 Mae + csto - cco + Мtov). horther, co, dissolved will also Reart, Con + Cocon - Coco + HD Total Cacon, used up; for 5 moles of cacos formed 4 miles of Ca com are used (as per Rx") Thus, to Remote, 16 mm carbonate species , malarity of ca con required. 4 x16 /12.9mm] Thus, pH of 128 mm Cacone is Cacohcete- ron 2 25-6x16*m7 12.8x2 pole.log(as. 6x0] : 1.512 Тиб, унг 4-рын -19.41]