1. Problem a: Determine which water among finished drinking water, raw wastewater, and de-ionized water has the highest carbonate hardness and why. Finished drinking water typically has moderate hardness due to treatment processes. Raw wastewater usually has high hardness because it contains dissolved minerals including calcium and magnesium bicarbonates. De-ionized water has very low hardness as ions are removed. Therefore, raw wastewater is expected to have the highest carbonate hardness because it contains the highest concentration of dissolved calcium and magnesium bicarbonates, which contribute to carbonate hardness. 2. Problem b: Calculate total hardness, carbonate hardness, and non-carbonate hardness for a sample with 50 mg/L Ca2+, 150 mg/L Mg2+, 50 mg/L Na+, 20 mg/L Cl-, and 100 mg/L glucose. First, recall that: - Total hardness (TH) = sum of Ca2+ and Mg2+ concentrations expressed as mg/L CaCO3 equivalent. - Carbonate hardness (CH) is due to bicarbonates (HCO3-) but as bicarbonate concentration is not given, it cannot be directly calculated here. - Non-carbonate hardness (NCH) = total hardness - carbonate hardness. Assuming all hardness is carbonate since no bicarbonate info is given is inaccurate; so alternatively, calculate total hardness as: Convert Ca and Mg from mg/L as ions to mg/L as CaCO3: Equivalent weight of CaCO3 = 100 g/mol Equivalent weight Ca2+ = 40 g/mol Equivalent weight Mg2+ = 24.3 g/mol So: $\text{Ca hardness as CaCO3} = 50 \times \frac{100}{40} = 125$ mg/L $\text{Mg hardness as CaCO3} = 150 \times \frac{100}{24.3} \approx 617.28$ mg/L Total hardness: $$TH = 125 + 617.28 = 742.28\ \text{mg/L CaCO3}$$ Since bicarbonates are not given, carbonate hardness and non-carbonate hardness can't be precisely computed. 3. Problem c: Procedure for determining water hardness: 1. Collect water sample. 2. Prepare reagents including EDTA solution and buffer solution at pH 10. 3. Add buffer to water sample to maintain pH. 4. Titrate the sample with standard EDTA solution using an appropriate indicator (e.g., Eriochrome Black T). 5. End point indicated by color change. 6. Calculate hardness concentration using volume of EDTA used. Summary: - Raw wastewater has highest carbonate hardness. - Total hardness calculated as approximately 742.28 mg/L CaCO3. - Hardness determination involves EDTA titration. Final answers: Raw wastewater expected highest carbonate hardness. Total hardness $\approx 742.28$ mg/L CaCO3. Procedure described above.