Separating mixtures
Separating a mixture never changes the substances: it only pulls them apart, which is why all these methods are physical and none is a reaction. The question is always the same: how do they differ physically? If it is size, filter — whatever does not fit through the paper's pores stays on top. If it is boiling point, distil, which is how alcohol is separated from water. If one evaporates and the other does not, evaporate, and that is how salt comes out of sea water. If one is magnetic, a magnet is enough. If they do not mix and have different densities, decant, like oil and water. And if they cling differently to paper, use chromatography. Beware one classic trap: filtering does not remove dissolved salt, because once dissolved it is no longer a loose solid but loose particles among the water's, and they go through just like the water.
Where this sits
- Comes after
- What everything is made of
- Opens up
- Chromatography and titration
Exercises from this rung
Generated by the app, from easiest to hardest
Why can you separate iron filings and sulfur?
- Because only the iron responds to a magnet
- Because the water leaves as vapour and the salt stays
- Because sand does not fit through the pores and water does
- Because they boil at different temperatures
Why Because only the iron responds to a magnet, and the method follows: using a magnet. Separating never changes the substances, it only pulls them apart: that is why these are **physical** methods and not reactions. If separating changed a substance, it would not be a mixture but a compound.
easierWhy can you separate sand and water?
- Because they boil at different temperatures
- Because only the iron responds to a magnet
- Because the water leaves as vapour and the salt stays
- Because sand does not fit through the pores and water does
Why Because sand does not fit through the pores and water does, and the method follows: filtering through paper. Separating never changes the substances, it only pulls them apart: that is why these are **physical** methods and not reactions. If separating changed a substance, it would not be a mixture but a compound.
in betweenPut the steps of a filtration in order.
Answer Pour the mixture into the funnel, The liquid goes through the paper, The solid stays on top, The clean liquid is collected below
Why Filtering separates by size: whatever does not fit through the paper's pores stays on top. It is no use for dissolved salt, because dissolved salt is no longer a loose solid but loose particles among the water's, and those go through just like the water.
harder