Question

Equimolar solution of nacl and bacl2 are prepared in water freezing point of nacl is found be -2c what freezing point do you expect for cacl2 solution

Answer 1

For the same molar concentration of NaCl and CaCl2, CaCl2 would be more effective in lowering freezing point. This is because freezing point depression is dependent on the number of ions present (colligative property). The more ions present in a solution, the greater the change in temperature. In general, NaCl has a value of i = 2 and CaCl2, i = 3 (van't Hoff factor, i). The expected value for i would be more accurate for more dilute solutions. This is because ion pairing can occur in concentrated solutions, e.g. a Na+ and Cl- can pair together and count as a single particle. In addition, the difference in expected and observed value of i is also greater for highly charged ions such as MgSO4.