posted by Supaman on .
For the autoionisation of water, it looks like
2H2O(l)-> H3O+(aq) + OH–(aq)
I thought that becuase it is going from liquid to ions, wouldnt the Entropy be greater than 0?
However, I have been told and I have calculated the opposite, that entropy is less than 0. Please Explain .
It is an endothermic process. The entropy change is the heat required divided by the temerature, and is negatve because heat energy must be supplied.
It is true that the process occurs spontaneously, but the reverse process is much more likely. That is why so few of the H2O molecules are ionized.