Question

The concentration of Mg⁺² ions in a sample of coastal seawater is 1.09g/Kg. What is the molarity of Mg⁺² in this seawater? (Assume the density of seawater is 1.02g/ml).

Answer 1

Molarity = (weight / molar mass) x (1000 / volume in ml)

Molar mass of Mg = 24.305 gram/moles;

Weight = 1.09g/1kg

Since density = mass/volume

volume of sea water = mass/density

= 1000 gram / 1.02 gram/ml

= 980.39 ml

Molarity = (1.09 / 24.305) x (1000 / 980.39)

= 0.044846 x 1.020

= 0.04574 moles/Liter