1. The problem statement, all variables and given/known data A clinical thermometer cannot be sterilised by placing it in boiling water. Why not? 2. Relevant equations none. 3. The attempt at a solution I assume the liquid is mercury. In the book they said a clinical thermometer has a kink at the end (so when it is out of the mouth it dosen't drop the down as fast - I made this up). Mecury boils at 630K so it should still be a liquid at the temperture water boils. I don't see why it can't be sterilised by placing it in boiling water as the sterilisation is meant to kill off microbes. I don't see any side effects. So I can't answer the question.