Chemistry - Paper Chromatography

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what type of process is paper chromatography?
a physical process (doesn't involve chemicals reaction + no new substances made)
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paper chromatography allows us to separate substances based on their....
solubilities (ability to dissolve)
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what could you find out in chromatography about different colour pens?
which pens have are made from a mixture of colours and which are made from just one as it would separate the ink into it's different colours.
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first step: draw straight line near bottom of chromatography paper. should be in pencil. why?
ink is soluble in water so ink from pen would move up paper with solvent. so would effect expeirment if used instead of penisl
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now place dot of ink(s) onto the pensil line. would should you control here?
time pen touches paper (area of ink dot)
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now place bottom of paper into a ___
solvent (liquid that can dissolve substances - water)
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make sure the line is above the solvent. why?
otherwise solvent (water) will wash stubstence off line (
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the solvent (water) goes up paper and ___ the ink, carrying them up the paper with solvent
dissolves/separates
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the paper is called the ___ stage become it doesn't move
stationary
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the solvent is the __ phase because it does move
mobile (definition: The liquid/gas that flows through a chromatography system, moving the materials to be separated at different rates over the stationary phase)
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what can we conclude if there's only one spot (colour) from an ink dot after the test?
that ink was pure (made up of only one colour)
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what can we conclude if separated into two spots?
it was a mixture of two different substances
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each chemical in the mistre (ink) will be attracted to paper to a different extent.true?
yes
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how far would chemicals that are strongly attracted to paper move?
not far - chemicals weakly attracted will move further
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what could you use to place food colouring on paper?
capillary tube (thin glass tube)
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spots should be small to prevent...
substances spreading into each other
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what can you do to reduce evaporation of solvent?
put lid on beaker
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if an unknown colour has spots that line up with colours A and B (example, could be any colours), what does that tell us about unknown colour?
it's a mixture of colours A and B
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how do you calculate Rf value?
measure distance from line to center of each spot to find out how far chemical moved.also measure distance the water moved, from pensil line. Rf value = distance chemical moved / distance solvent moved
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what units do Rf values have?
none. they don't have any units
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how can we get more accurate results for Rf value?
repeat experiment with different solvents
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Other cards in this set

Card 2

Front

paper chromatography allows us to separate substances based on their....

Back

solubilities (ability to dissolve)

Card 3

Front

what could you find out in chromatography about different colour pens?

Back

Preview of the front of card 3

Card 4

Front

first step: draw straight line near bottom of chromatography paper. should be in pencil. why?

Back

Preview of the front of card 4

Card 5

Front

now place dot of ink(s) onto the pensil line. would should you control here?

Back

Preview of the front of card 5
View more cards

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