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separating mixtures Flashcards

1
Q

solute

A

dissolved in the solvent

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2
Q

solvent

A

what dissolves the solute

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3
Q

in a solution of salt and water, what is the solute?

A

salt

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4
Q

in a solution of salt and water, what is the solvent?

A

water

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5
Q

immiscible meaning

A

two liquids that do NOT mix in a homogenous solution

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6
Q

solubility meaning

A

the mass of a solid required to saturate 100 g of water at a given temperature. Solubility is measured in grams of a solute per 100 g of water.

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7
Q

what is the mobile phase in paper chromatography?

A

the solvent eg water or ethanol

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8
Q

what is the stationary phase in paper chromatography?

A

the paper

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9
Q

why is the baseline drawn in graphite (pencil)?

A

bc it’s insoluble so will not move

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10
Q

how do you work out the rf value?

A

distance the pigment has moved
___________________________________
distance the solvent has moved

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11
Q

what does the rf value show?

A

the solubility of substances on certain papers in certain solvents

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12
Q

what is the solvent front?

A

highest point reached by solvent

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13
Q

how do you separate insoluble solid and liquid mixture? + eg

A

filtration
water from water and sand

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14
Q

how do you separate solutions of solid in liquid? (obtain liquid) + eg

A

distillation
water from salt water

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15
Q

how do you separate solutions of solid in liquid? (Obtain solid) + eg

A

evaporation
salt from a sea water

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16
Q

how do you separate two miscible liquids? + eg

A

fractional distillation
crude oil/ water and ethanol

17
Q

how do you separate several solids that are all soluable in the same solvent? + eg

A

chromatography
dyes in an ink

18
Q

how do you separate two immiscible liquids? + eg

A

separating funnel (run off the more dense liquid by opening tap)
oil and water

19
Q

how do you remove both insoluble and solvable impurities and purify a solid?

A

re-crystallisation

20
Q

how does distillation work?

A
  • the heat evaporates the liquid with the lower boiling point which condenses into a liquid as it passes through the water jacket (condenser)
  • the pure liquid (dissalate) is collected and the residue, which has a higher boiling point, is left in the flask
21
Q

how does filtration work?

A

as the mixture passes through the filter paper and funnel, the liquid filtrate passes through and the solid residue remains on the filter paper

22
Q

how does fractional distillatio work?

A
  1. mixture of miscible liquid is placed in a flask and heated
  2. mixture boils and vapours from both/all liquids pass into the fractionating column but there is a higher proportion of the one with s lower boiling point
  3. the vapour which has a lower boiling point emerges from the top of the column first in a pure state and passes into the codenser
  4. when all of this liquid has distilled over it is followed by the liquid with the highest boiling point
  5. thermometer measures the bpt of the liquid distilling over
23
Q

how does chromotography work?

A

dyes which are more soluable move faster up the paper and less soluable dyes move slower which separeates them out on the paper.

24
Q

what is a pure substance?

A

a substance that is completly made up of a single element or compound

25
Q

how do you test for purity?

A
  • a pure substance will have a sharp (very specific) boilig poit eg water freezes at 0 C
  • an impure substance will melt gradually over a range of substaces
26
Q

how does crystallisation work?

A
  1. the solution into the evaporatig dish and gently heat it - some liquid will evaporate, it will become more concentrated
  2. once some water has evaporated, remove dish from heat and leave to cool
  3. the dissolved compound will start to form crystals as it becomes insoluable in the cold, highly concetrated solution
  4. filter out the crystals and leave to dry in a warm place
27
Q

how can ground water be purified? (3)

A
  1. filtration (remove large solids eg rocks)
  2. sedimentation ( iron/aluminium sulfate added which clumps fine particles and makes them sink to the bottom)
  3. chlorination ( chlorine gas bubbled through to kill harmful bacteria and other microbes
28
Q

how can sea water be made potable?

A

in some dry countries, not enough ground water o sea water is DISTILLED

30
Q

what is a mixture?

A

a group of substances that are not chemically bonded together

31
Q

methods of separating mixtures (6)

A
  1. simple distillation
  2. fractional distillation
  3. filtration
  4. re-crystallisation
  5. chromotography
  6. separating funnel (immiscible liquids)
32
Q

properties of mixtures (4)

A
  1. proportions may vary
  2. properties are simply those of the elements
  3. can be separated by a physical change
  4. no energy change when the elements are mixed

gcse chemistry (12 decks)

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