1. When 26 mL of a 375 mL stock solution containing 2.1 M CaCl2 is diluted to 103 mL, how many moles of Ca2+ are in the new solution?
2. How many milliliters of a 220 mL solution of 1.5 M AlCl3 must be used to make 61 mL of a solution that has a concentration of 0.3 M Al3+?
3. A 9 mL sample of a solution of AlBr3 was diluted with water to 25 mL. A 17 mL sample of the dilute solution was found to contain 0.042 moles of Br-. What was the concentration of AlBr3 in the original undiluted solution?