Question

2. A water sample is taken from a stream in Nevada receiving acid mine drainage. The stream passes through an area containing gypsum CaSO4. Laboratory analysis shows that the pH of the water is 4, the total concentration of sulfate (SO42-) is 6 x 10-M, and the total concentration of chloride (C1) is 3 x 10-4M. a) Assuming that the only other ionic species present is calcium (Ca?), what is the calcium concentration in the water?

Answer 1

The calcium ion concentration in the water sample is found to be 6.2 x 10-3 M.

Solution is [s042-) = 6X10-3 M [ue] = 3x10-4M pH za 5 (H+) z 1x10-4 M ③ we have to calculate the conc. of [Ca 2+] in the water, sample " 'According to electoneutrality principle & cone.of cations (ie cation'species) = conc.cf aniors lise anionic species) [H+] + [ Ca2+] = [ 8042-+ ue] hemu 1x10-4M + Ca 2+] 6X107 M + 3x10-4M or [ 69 2+3 z 6x10-2M + 3x10-4M – 1*10-4m 6x103M + 2x10-4M. Tra 2+1 6+2x10-3m7 z 10-3 ( 6+ 0.2) m . or lo in water sample Ang/