separation techniques

Question 1

filtration

Answer 1

• separates solid from a liquid
• usually using filter paper
• ex is separating sand water

Question 2

evaporation

Answer 2

• recover a dissolved substance
• if salt water is left in open air then eventually the water will all evaporate away leaving the solid salt behind
• works very well with volatile solvents such as ethanol, acetone or ether
• ** used to separate 2 liquids, esp if theres a huge diff in boiling points

Question 3

distillation

Answer 3

• similar to evaporation but here its capturing the solvent
• the solvent is boiled off, but then instead of escaping into the air we condense it back into a liquid and keep it.

Question 4

recrystallization

Answer 4

• this is used when we have a mixture of two solids and we want to recover the one that is soluble
• used to purify solid compounds
• the compound is dissolved in a hot solvent, then allowed to cool and form crystals
• as the solution cools, pure crystals form while impurities are left behind

Question 5

decanting

Answer 5

• when there is a suspension of a solid in a liquid we might allow the solid to settle to the bottom and them carefully pour off (decant) the liquid

Question 6

centrifuge

Answer 6

• centrifuge spins around very fast
• will speed up the separation of a mixture into layers
• solid and liquid or two liquids (or two gases)
• separates isotopes

Question 7

separating funnel

Answer 7

• a separating funnel is used when two liquids do not mix (not homogenous)
• two layers should be seen

Question 8

fractional distillation

Answer 8

• separates a mixture like crude oil into different fractions based on the boiling points