Which of the following solutions of strong electrolytes contains the largest number of moles of chloride ions?

Question

100.0 mL of 0.30 M AlCl3

50.0 mL of 0.60 M MgCl2

200.0 mL of 0.40 M NaCl

do the mL matter in this question?

Answer 1

To solve for number of mols we must determine how many mols of each substance there is.  To do this we multiply the volume by the concentration. Then we multiply this by how many Cl- atoms are in each molecule:

1. 100mL * (1L/1000mL) * 0.3 mol/L * 3 Cl-/molecule AlCl3 = 0.09 mol Cl-

2. 50mL * (1L/1000mL) * 0.6 mol/L * 2 Cl-/molecule MgCl2 = 0.06 mol Cl-

3. 200mL * (1L/1000mL) * 0.4 mol/L * 1 Cl-/molecule NaCl = 0.08 mol Cl-

Therefore, 100.0 mL of 0.30 M AlCl3 contains the largest number of mols of Cl- ions.

Answer 2

100.0ml of 0.30M AlCl3

Answer 3

Yes, the mL matter

100.0 mL x 0.30 M x 3 = 90 millimoles of Cl- (AlCl3)

50.0 mL x 0.60 M x 2 = 60 millimoles Cl- (MgCl2)

200.0 mL x 0.40 M x 1 = 80 millimoles Cl- (NaCl)