C2.1.4 Filtration And Crystallisation Flashcards
How does a solution form?
A solution forms when one substance dissolves in another.
What is the solute?
The solute is the substance that dissolves,
What is the solvent?
The solvent is the substance it dissolves in.
What happens when a substance dissolves?
When a substance dissolves, its particles separate and become completely mixed with the particles of the solvent.
How can a substance be soluble?
If the substance can dissolve in a particular solvent.
When is a substance insoluble?
If it cannot dissolve, it is insoluble in that solvent.
What does filtration do?
Filtration separates an insoluble substance in the solid state from substances in the liquid state.
Why does filtration work?
It works because filter paper has tiny, microscopic holes.
What is the filtrate
The substance that passes through.
What is the residue?
The substance that stays behind in the filter.
How does crystallisation work?
If you heat a solution, the solvent evaporates leaving the solute behind.
If you heat the solution too strongly, you get a powder
But if you allow the solvent to evaporate slowly, you get regularly shaped crystals.
Why does crystallisation require patience?
Crystallisation takes patience because you need to heat the solution gently until it becomes a saturated solution.
When do you know a solution is saturated?
A solution is saturated when no more solute can be dissolved at that temperature.
