Question

A different consideration of hardness is an issue that applies to the chemistry of swimming pool water. In this case, appreciable hardness is desired because it deters the pool water from leaching minerals, for example, from tile grout. You analyze the pool water for a friend and determine it has calcium hardness of 175 mg/L as CaCO3. The professional pool maintenance guideline is that calcium hardness should be between 5 and 10 millimoles Ca2 per liter. You convert the concentration expressed as 175 mg/L CaCO3 to compare it to the Ca2 guideline. What is the concentration of Ca2 in mM

Answer 1

Answer:

1.748 mM

Explanation:

Concentration in g / L = Molarity × molar mass

molar mass of calcium carbonate = 100.0869 g/mol

175 mg/L =    175 ÷ 1000 = 0.175 g/L

0.175 g/L = Molarity × 100.0869 g/mol

(0.175 g/L) / 100.0869 = Molarity

Molarity = 0.001748 M

CaCO₃ → Ca²⁺ + CO₃²⁻ when it dissociate in water.

1 M of  CaCO₃ yielded 1 M of Ca²⁺

0.001748 M of  CaCO₃ will also yield 0.001748 M of  Ca²⁺

then 0.001748 × 1000 = 1.748 mM concentration of Ca²⁺