Exercise 6 | Chemical Calculations for Solutions

Copper(II) chloride is a strong electrolyte.

1) What is the total number of moles of ions present in 50.0 mL of a 0.250 M copper(II) chloride aqueous solution?

2) What is the ionic strength of this solution?

1) Copper(II) chloride: CuCl2 (s)

CuCl2 (s) + H2O (l) → Cu2+ (aq) + 2 Cl- (aq)

0.250 M copper(II) chloride ⇒ 0.250M of Cu2+ and 0.500M of Cl-

 

Moles of Cu2+

nCu2+ (in mol) = MCu2+ (in mol.L-1)  x V (in L)
nCu2+ = 0.250 x 50.0 x 10-3 = 1.25 x 10-2 mol


Moles of Cl-

nCl- (in mol) = MCl- (in mol.L-1)  x V (in L)
nCl- = 0.500 x 50.0 x 10-3 = 2.50 x 10-2 mol


Total number of moles = (1.25 + 2.50) x 10-2 = 3.75 x 10-2 moles

 

2) I = 12 i = 1n ci zi2

I = 12MCu2+ x 22 + MCl- x (-1)) = 12 (0.250 x 4 + 0.500) = 0.75M