Chemistry Paper 1

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  • Created by: Morgan.K
  • Created on: 29-05-18 17:16
Define the term 'pure substance' - (in chemistry terms)
a single element or compound
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does a pure substance have a range of melting and boiling points, or one specific melting and boiling point?
one specific melting and boiling point
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does an impure substance have one specific melting and boiling point of a range of melting and boiling points?
a range of melting and boiling points.
3 of 58
on a temperature/time graph, what do the flat lines represent?
the melting and boiling points
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define the term 'formulation' -
a complex mixture that has been designed as a useful product.
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how do formulation get specific properties?
the quantity of each product is carefully measured.
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give three examples of formulations -
any three from - fuels, cleaning products, paints, medicines, alloys, fertillisers and food.
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is chromatography a physical or chemical process?
physical process
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why is chromatograghy a physical process?
because it does not involve a chemical process and no new substances are made.
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what does paper chromatography allow us to do?
separate substances based on their different solubilities
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what is a solvent?
a liquid that will dissolve substances
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what is the stationary phase in chromatography? and why do we call it that?
the paper because it doesn't move.
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what is the mobile phase in chromatography? and why do we call it this?
the solvent because it does move
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how can you tell, from paper chromatography, that the substance is pure?
there will only be one dot with one colour.
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how can you tell, from paper chromatography, that the substance is impure?
more that one dot and colour will be formed.
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why do some colours move higher up the paper?
because different substances will have a different attraction to the paper
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if a coloyr hasn't moved very far up the stationary phase, does this mean it has a strong attraction or a weak attraction to the paper?
a strong attraction.
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if a colour has moved far up the paaper, does this mean it is strong ly attracted to the paper or weakly attracted?
weakly attracted.
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if a pure substance is placesd into a differnt solvent, will it frm more coloured spot?
No
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why do we draw the start line in pencil? (in paper chromatography)
if we drew the line in pen, the pen ink would move up the paper, with the solvent
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in paper chromatography, what is used to place the ink onto the paper?
a capillary tube
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what is a capillary tube?
a very thin glass tube
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why do we not allow the water to go over the pencil line in paper chromatography?
otherwise, the water would wash the ink off the line.
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why must we not let the sides of the paper touh the sides of the beaker?
it could interfere with the way the water moves
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why do we place a lid on the beaker in paper chromatography?
to reduce the evaportation of the solvent
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how do you work out the Rf value?
distance moved by chemical ÷ disatnec moved by solvent
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do Rf values have a unit?
No
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how do we use the Rf value to determine what substance it is?
we look it up in a database
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how do we test for hydrogen?
by placing a lit splint in a test tube of a gas and listening for a squeeky pop sound.
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why does hydrogen make a squeeky pop when in the presence of a flame?
because it burns rapidly.
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what is the test for oxygen?
if a glowing splint is in the presence of oxygen, it will relight
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how do we test for carbon dioxide?
a test tube of lime water will go milky when carbon dioxide is bubbled through it.
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what is lime water?
an aqueous solution of calcium hydroxide
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what is the test for chlorine?
chlorine will bleach damp litmus paper white.
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what colour is litmus paper?
Red
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what colour does lithium go when burning?
Crimson
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what colur does sodium go when burning?
yellow
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what colour does potassium go when burning?
lilac
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what colour does calcium go when burning?
orange-red
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what colour does copper go when burning?
green
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what are the problems with a flame test?
the colour of the flame can be hard to distinguish and sometimes a sample can contain a mixture of metal ions, which masks the colour of the flame.
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what two things can flame emission spectroscopy tell us?
which metal ions are included and the concentration of them.
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what does 'instrumental method' mean?
it is carried out by a machine.
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is flame emission spectroscopy an instrumental method?
yes.
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what are the three benefits of flame emission spectroscopy?
they are rapid, sensitive and accurate.
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when aluminium ions are mixed with sodium hydroxide, what happens?
it forms a white precipitate.
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when sodium hydroxie is added in excess to aluminum ions, what happens?
the white precipitate formed redissolves.
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what happens what copper 2 ions react with sodium hydroxide?
a blue precipitate is formed.
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what happens when iron 2 ions react with sodium hydroxide?
a green precipitate is formed.
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what happens when iron 3 ions react with sodium hydroxide?
a brown precipitate is formed.
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what happens when calcium ions are added to sodium hydroxide?
a white precipitate is formed.
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what happens when magnesium ions are added to sodium hydroxide?
a white precipitate is formed.
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how do scientists distinguish between calcium and magnesium ions?
by using a flame test, as they both produce a white precipitate.
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what happens when a carbonate ion is added to a dilue acid?
the acid will rect with the carbonate to make carbon dioxide gas.
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what does effervescence mean?
fizzing
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what colour precipitate do chloride ions go?
white
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what colour precipitate do bromide ions go?
cream
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what colour precipitate do iodide ions go?
yellow
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Other cards in this set

Card 2

Front

does a pure substance have a range of melting and boiling points, or one specific melting and boiling point?

Back

one specific melting and boiling point

Card 3

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does an impure substance have one specific melting and boiling point of a range of melting and boiling points?

Back

Preview of the front of card 3

Card 4

Front

on a temperature/time graph, what do the flat lines represent?

Back

Preview of the front of card 4

Card 5

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define the term 'formulation' -

Back

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