a question for Dr Nick:
Just for Dr Nick?
Water boils at precisely 100 degrees Celsius only when pure and at exactly one standard atmosphere pressure - 1.015 (x ten to the power five) Pascals - Any other conditions and the temperature at which it boils will change.
The boiling point reduces as the pressure reduces, and generally increases as more dissolved solids are present (there are likely a few exceptions to the latter generality).
With miscible liquids there is a set boiling point for any particular mixture (at a given pressure), so the boiling point of a mixture would change from the temperature of one component to that of the other other as the percentage changed from 100% to 0% of the particular component. Solutions of solids are a little different from the simpler case of miscible liquids.
Some mixtures (generally of liquids) attain a' constant boiling point' where the components are in equilibrium at that particular temperature and both components change state while the mixture % remains constant.
In the case of sugar solutions in water, the increased boiling point increase holds true until the temperature rises to a point where the sugar starts to decompose.
Therfore all done at atmospheric pressure, so no pressure cooker needed.
Hope that litle lot helps a bit.
Regards, RAB
