Question

The i value assumes that an ionic compound dissociates 100% in solution. Is this true? Explain this by considering the percent difference in ΔT values and the behavior of ions in solution (you might want to read up on ion behavior). This is looking at three different compounds Nacl with delta T of .9 degree celcius and Na2SO4 with a delta t value of 1.1 and Na3 PO4 of a delta t of 1.5. Each of these compounds in increasing order have vant hoff factors of 2, 3 and 4.

Answer 1

The i value assumes that an ionic compound dissociates 100% in solution. However, this assumption is not true. If this assumption was true, then delta T would be directly proportional to the vant hoff factor. However from given data, we can see that this is not the case.

For sodium sulphate and NaCl, the ratio of vant hoff factors is 3/2 = 1.5 And the ratio of delta T is 1.1/0.9=1.22. Two ratios are different. Thus dissociation is not 100%

Similalry For sodium phosphate and NaCl, the ratio of vant hoff factors is 4/2 = 2 And the ratio of delta T is 1.5/0.9=1.67. Two ratios are different. Thus dissociation is not 100%