Here's how to calculate the alkalinity and arrive at the solution: **Understanding Alkalinity** Alkalinity is the capacity of water to neutralize acids. In most natural waters, it's primarily due to the presence of bicarbonate (HCO₃⁻), carbonate (CO₃²⁻), and hydroxide (OH⁻) ions. Since the pH is close to 7.0, we can assume that bicarbonate (HCO₃⁻) is the dominant contributor to alkalinity. **Calculation Steps** 1. **Convert HCO₃⁻ concentration from mg/L to meq/L (milliequivalents per liter):** * **Molar mass of HCO₃⁻:** 1 (H) + 12 (C) + 3 * 16 (O) = 61 g/mol * **Equivalent weight of HCO₃⁻:** Since HCO₃⁻ has a charge of -1, its equivalent weight is equal to its molar mass: 61 g/eq * **meq/L of HCO₃⁻:** (160.0 mg/L) / (61000 mg/eq) = 0.002623 eq/L 0.002623 eq/L * 1000 meq/eq = 2.623 meq/L 2. **Convert meq

Here's how to solve this problem, along with explanations to help you understand the steps: **Understanding Alkalinity** Alkalinity is a measure of a water's ability to neutralize acids. In natural waters, it's primarily due to the presence of bicarbonate (HCO₃⁻), carbonate (CO₃²⁻), and hydroxide (OH⁻) ions. Since the pH is close to 7, bicarbonate is the dominant alkalinity contributor. **Steps to Calculate Alkalinity as CaCO₃** 1. **Identify the Alkalinity-Contributing Ion:** In this case, it's HCO₃⁻ (bicarbonate). 2. **Calculate the Equivalent Weight of HCO₃⁻:** * Molecular weight of HCO₃⁻ = 1 (H) + 12 (C) + 3 * 16 (O) = 61 g/mol * Since HCO₃⁻ has a charge of -1, its equivalent weight is equal to its molecular weight: 61 g/equivalent. 3. **Calculate the Equivalent Weight of CaCO₃:** * Molecular weight of CaCO₃ = 40 (Ca) + 12 (C) + 3 * 16 (O) = 100 g/mol * Since Ca²⁺ has a charge of +2 (and CO₃²⁻ has a charge of -2), CaCO₃ has