It turns out that "colligative properties" are all based on how many particles of solute are dissolved in the solution. It doesn't matter what the particles are, just how many of them you have.
The number of particles in a solution affect three colligative properties: vapour pressure, melting temperature and boiling temperature. How much these properties are affected depends on how many particles of solute there are in the solution.
The reason I say particles is because molecules, atoms and ions all count as particles. So if you have, say 1 mole of glucose and 1 mole of sodium chloride, the 1 mole of sodium chloride actually has more particles because it contains 1 mole of Na + ions and 1 mole of Cl - ions (2 moles total) whereas the glucose just has 1 mole of glucose molecules. And, as I said before, it doesn't matter what the particles are, it just matters how many particles you have.
Now, these particles of solute sometimes get in the way of evaporation. You see, if there are solute particles near the top, they'll inhibit any solvent particles beneath them that might want to evaporate. As fewer particles can evaporate, the vapour pressure of the solution is decreased. And, since vapour pressure has to be as high as atmospheric pressure to boil, you have to heat the solution up even more until this happens. Therefore, boiling point is also increased.
Melting point is decreased because the solute particles get in the way of the bonds that need to form for the solvent to solidify.
Next up: applications of electrolysis, another topic I've found that I don't know a whole lot about!
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