Question

Maple syrup has a density of 1.325 g/ml, and 100.00 g of maple syrup contains 67 mg of calcium in the form of ca2+ ions. what is the molarity of calcium in maple syrup?

Answer 1

Density of maple syrup = 1.325 g/ml
1000 ml contains 1325 g of maple syrup
In 100 g of maple syrup - 67 mg of Ca ions
Therefore in 1325 g of maple syrup - 67 mg /100g * 1325 g 
                                                        = 887.75 mg of Ca
this means in 1000 ml - 887.75 mg of Ca
molar mass of Ca - 40 g/mol
therefore number of moles in 1000 ml - 0.88775 g /40 g/mol
molarity of Ca - 0.022 mol/dm³

Answer 2

Explanation:

As density is mass divided by volume. And, it is given that mass of maple syrup is 100.00 g and its density is 1.325 g/ml.

Hence, volume of this maple syrup will be calculated as follows.

               Volume = $\frac{mass}{density}$

                             = $\frac{100 g}{1.325 g/ml}$

                             = 75.47 ml

or,                          = 0.07547 L          (as 1 L = 1000 ml)

Also, number of moles = $\frac{mass}{\text{molar mass}}$

It is given that mass of calcium present in maple syrup is 67 mg and molar mass of calcium is 40 g/mol.

Hence, calculate the number of moles of $Ca^{2+}$ ions as follows.

           number of moles = $\frac{mass}{\text{molar mass}}$

                                        = $\frac{67 mg}{40 g/mol}$        

                                        = 1.675 mol

As molarity is the number of moles present in liter of solution. Hence, calculate the molarity of calcium in maple syrup as follows.

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

                           = $\frac{1.675 mol}{0.07547 L}$

                           = 22.19 M

Therefore, we can conclude that molarity of calcium in maple syrup is 22.19 M.