Determine the mass of CaCl2·2H2O(MW 147.02g/mole) to weigh out using a four-place analytical balance to prepare 100mL of a 0.1005M solution of Ca2+.

1.4776 g

Explanation:

First, let us determine the number of moles present in  100 mL of 0.1005 M solution of Ca2+.

mole = molarity x volume in Liter

mole of Ca2+ = 0.1005 x 0.1 = 0.01005

Also,

mole = mass/molar mass

mass of 0.01005 mole Ca2+ = mole x molar mass

                 = 0.01005 x 147.02 = 1.4776 g

Since 1 mole of Ca2+ is present is 1 mole of CaCl2·2H2O, 1.4776 g of CaCl2·2H2O would be weighed out in order to prepare 00mL of a 0.1005M solution of Ca2+.