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9b Chemistry > C2 experimental techniques > Flashcards

C2 experimental techniques Flashcards

1
Q

Describe Chromatography

A

A method of separating mixtures of soluble substances

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2
Q

Describe mixture

A

contains 2 or more substances not chemically combined

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3
Q

Describe Solvent

A

a substance that dissolves a solute

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4
Q

Describe stationary phase in chromatography

A

the paper in paper chromatography

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5
Q

Describe mobile phase in chromatography

A

the solvent in paper chromatography

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6
Q

Describe chromatogram

A

shows the results of separating the components of a mixture by chromatography

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7
Q

Describe impure substance

A

made of more than one thing and produces two or more spots on a chromatogram

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8
Q

Describe Rբ value

A

A way of measuring how far a spot has travelled on a chromatogram compared to the distance the solvent has travelled

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9
Q

Solvent front

A

the furthest point the solvent travels in paper chromatography

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10
Q

describe solute

A

a substance that is able to dissolve in a solvent

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11
Q

describe pencil line

A

doesn’t dissolve in the solvent so can be used as a baseline to make measurements in paper chromatography

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12
Q

What types of separation techniques are there? [4]

A

-Filtration
-Chromatography
-Crystallisation
-fractional/simple distillation

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13
Q

Describe Filtration [4]

A

-separates mixtures of insoluble solids and liquids
-by pouring mixture through filter paper
+solid trapped
+liquid run through

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14
Q

Describe Crystallisation [5]

A

-separates solutions into their contituent(different) parts
-solutes and solvents
-by heating the mixture so that the solvent evaporates
+crystal solutes
+collected solvent by condensing as it evaporates

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15
Q

Describe Fractional distillation

A

separates liquids with different boiling points
-mixture heated until the liquid with lowest boiling point boils and condenses
-increase temperatuer to collect the other fractions

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16
Q

Describe simple distillation

A

separates 2 liquids with different boiling points
-mixture heated until the liquid with lower boiling point boils
-vapour passes through condenser and cools to liquid

17
Q

What equipment is used to measure time and what is the unit?

A

stopwatch, seconds

18
Q

what equipment is used to measure temperatuer and what is the unit?

A

thermometer, degrees celsius

19
Q

what equipment is used to measure mass and what is the unit?

A

Mass balance, grams

20
Q

What 3 equipments are used to measure volume of liquid and what is the unit?

A

-measuring cylinder, volumetric pipette, burette
-cm3

21
Q

what equipment is used to measure volume of gas and what is the unit?

A

gas syringe, cm3

22
Q

what process is used to seperate two or more solids that are soluble?

A

Paper chromatography

23
Q

define pure substance

A

a substance that contains a single element or comound not mixed with any other substance

24
Q

How do you calculate Rf values in paper chromatography?

A

Distance moved by solute/distance moved by solvent (solvent front)

25
Q

describe 3 ways that the purity of a substance can be assessed

A

melting point, boiling point, chromatography

26
Q

Describe how melting point/boiling point can be used to assess purity

A

pure - exact melting/boiling point
impure - range of melting/boiling point

27
Q

describe how chromatography can be used to assess purity

A

pure-only produce only one well defined spot on a chromatogram

28
Q

describe two examples of where purity of substances is important [2]

A

manufacture of compounds used in drugs food additives

29
Q

describe solution

A

liquid mixture composed of two or more substances

30
Q

define volatility

A

How easily a substance evaporates/changes from a liquid to a gas

31
Q

define solubility

A

How easily a substance dissolves

32
Q

what is the filtrate in filtration

A

the liquid or solution that has passed through the filter

33
Q

What is distillation used for

A

to seperate a solvent from a solution

34
Q

How do you get a pure dry substance?

A

-isolate the substance
-dissolve it in water (dissolves soluble impurities)
-Evaporate the water

9b Chemistry (8 decks)

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