Asample of lake water at 25°c is analyzed and the following parameters are found: total alkalinity = 6.2 x 10-4 m phenolphthalein alkalinity = 1.0 x 10pm ph = 7.6 hardness = 30.0 mg/l [mg²+] = 1.0 x 10-4 m extract all possible single-ion concentrations that you can by combining one or more of these data. also determine whether or not the water is at equi- librium with respect to the carbonate-bicarbonate system and whether or not it is saturated with calcium carbonate.

Explanation:

The given data is as follows.

       Temperature = ,     Total alkalinity = M

      Alkalinity of phenolphthalein = M

       pH = 7.6,          Hardness = 30 mg/L

        M

It is known that total alkalinity is as follows.

       Total alkalinity =

Since,    pH = 7.6. Hence, concentration of hydrogen ions will be calculated as follows.

                          pH =

                          7.6 =

                    = antilog (-7.6)        

                                  = M

As,    pH + pOH = 14

               pOH = 14 - pH

                        = 14 - 7.6

                        = 6.4

So,    

                      =

Phenolphthalein alkalinity =

      = Total alkalinity - 2[CO^{2-}_{3}] - [OH^{-}] + [H^{+}][/tex]

                        =

                         =

=

          = 2.4 mg/L

Ratio of molar mass of and with is as follows.

          = = 25

          = = 4.2

Total hardness =

                         =

  =        

                                  =

        of =

Since,     >

Hence, the water is slightly unsaturated with .