Why is the experimental molar mass of the sodium chloride so much lower than that accepted value?

Question

What is it about sodium chloride that causes this effect?Is this effect the same for all sodium chloride solutions,regardless of concentration?Did supercooling affect it?Is it possible that the solution did actually freeze in some of the runs?Why cryoscopy not a commonly used method of molar mass determination in modern chemistry?

Answer 1

It looks as if you did a depression of freezing point experiment. What you probably did not do was to take account of the fact that NaCl consists of two ions, and so has twice the effect. This would make the Mr appear to be half of its correct value.