07 chem ce #17

Note that the chemical formula of calcium chloride is CaCl2.

So, For one CaCl2 compound molecule, there should be 2 Cl- ions. For the solution contains 1.0 X 10^-2 moles of Cl- (aq) ions, there should be (1.0 X 10^-2) / 2 = 5 X 10^-3 moles of the compound in aqueous form.

By molarity = no. of mole / volume

= (5 X 10^-3)(0.020)

= 0.25 M

= 2.5 X 10^-1 M.

Ans: C

2009-03-06 07:33:18 補充：
不是，而是要找出它們的molar ratio。