Question

A sample of water on analysis is found to contain 32 mg/l of mghco3 and 20 mgco3 . What is temporary hardness

Answer 1

Explanation:

moles of Mg(HCO₃)₂ = 32 × 10⁻³/ 146.33

                                   = 2.19 × 10⁻⁴ moles

moles of MgCO₃ = 20 × 10⁻³/84.31

                             = 2.37 × 10⁻⁴ moles  

Total moles of Mg = 4.5 × 10⁻⁴ mole

mass of MgCO₃ = 4.5 × 10⁻⁴ × 100

                           = 0.045 g  

Temporary hardness =  0.045 g /100 × 10⁶

                                   = 450ppm