Shown below are the results of waterquality analyses of a groundwater source. Because all of theconstituents were not analyzed, an ion balance may not be achieved.The pH of the water is 7.6.
a. (8 points) Prepare a barchart of water composition.
b. (6 points) Based on thebar chart, determine the total hardness, carbonate hardness,non-carbonate hardness, and alkalinity (in the unit of mg/L asCaCO3).
c. (6 points) Estimate theconcentrations of carbonate (CO32-) in thewater. Express your answer in mmol/L. Given that pKa1and pKa2 of H2CO3 are 6.35 and10.33, respectively.
d. (6 points) Dolomite(CaMg(CO3)2(s)) is found in the aquifersediment where the water sample was collected. Based on the watercomposition, is dolomite dissolving or precipitating? Given thatthe Ksp of CaMg(CO3)2(s) is10-17.09.
Constituent | Concentration (mg/L as the ion) |
calcium (Ca2+) | 150.3 |
magnesium (Mg2+) | 14.6 |
total iron (Fe3+) | 1.2 |
sodium (Na+) | 100.0 |
bicarbonate (HCO3-) | 450.0 |
chloride (Cl-) | 201.4 |
