Question

There is about 1.0 g of calcium as Ca2+ in 1.0 L of milk. What is the molarity of Ca2+ in milk?

Answer 1

Explanation:

It is known that molarity is the number of moles present in a liter of solution.

           Molarity = $\frac{\text{no. of moles}}{volume}$

Also, number of moles equal mass divided by molar mass. And, molar mass of calcium is 40.07 g/mol.

               No. of moles = $\frac{mass}{\text{molar mass}}$

                                     = $\frac{1.0 g}{40.07 g/mol}$

                                     = 0.025 mol

Therefore, calculate the molarity as follows.

             Molarity = $\frac{\text{no. of moles}}{volume}$

                            = $\frac{0.025 mol}{1.0 L}$  

                            = 0.025 M

Thus, we can conclude that molarity of $Ca^{2+}$ in milk is 0.025 M.