Separating Mixtures Flashcards
What does filtration do?
It separates an insoluble substance from a solution
How does filtration work?
The tiny pores in the filter paper trap insoluble particles but allow dissolved substances through
What does crystallisation do?
It separates solutes from a solution by evaporating the solvent to leave the solute behind
What are the three steps of crystallisation?
1) Solution is heated to produce a saturated solution
2) Crystals form in the solution
3) Crystals are separated from the liquid and dried
How are larger crystals made during crystallisation?
If the crystals form slowly, the particles have longer to form orders patterns and will be bigger
What does simple distillation do?
Separates a solvent from a solution (eg. sea water)
Why does simple distillation work?
Because the solute has a much higher boiling point than the solvent when heated
What does fractional distillation do?
Separates a liquid from a mixture of miscible liquids (mixed completely together)
Why does fractional distillation work?
Because the liquids in the mixture have different boiling points
What does paper chromatography do?
Separates mixtures of soluble substances
During chromatography, what is the substance called that does not move?
A stationary phase (eg. ink)
During chromatography, is the solvent a stationary phase or a mobile phase? Explain
Mobile phase - it moves through the stationary phase and up the paper
How do you calculate the Rf value for chromatography?
Distance travelled by spot ➗ Distance travelled by solvent
How does paper chromatography work?
More soluble compounds are carried up the paper faster than less soluble ones, so the compounds separate
What must potable water have?
Low levels of contaminating substances, low levels of microbes
