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CHEMISTRY > C12 > Flashcards

C12 Flashcards

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1
Q

define solute

A

a substance which dissolves

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2
Q

what is a solvent

A

the substance which does the dissolving

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3
Q

what is a solution

A

a substance with a mix of the solvent and solute

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4
Q

what is paper chromatography

A

a method to separate mixtures of colour compounds

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5
Q

what are some examples of substances which are suitable for paper chromatography

A

inks, dyes and food colourings

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6
Q

what is the base line

A

the line at which the inks are placed on

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7
Q

what is the mobile phase

A

it is the solvent chosen which moves up through the chromatography paper

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8
Q

what is the stationary phase

A

the chromatography paper

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9
Q

If a substance has a stronger force of attraction to the mobile phase, what happens

A

the compound will travel a greater distance in a given time

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10
Q

If a substance has a stronger force of attraction to the stationary phase, what happens

A

the compound will not travel far in the same time

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11
Q

what is Rf value

A

the retention factor

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12
Q

what is Rf value used for

A

it is used for comparing the components of various samples

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13
Q

what is the solvent front

A

the point at which the solvent stopped moving up the paper

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14
Q

what is the solvent front also known as

A

the solvent height

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15
Q

how do you calculate the Rf value

A

distance from base line to the centre of the ink spot divided by distance from base line to the solvent front

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16
Q

if two substance have the same Rf value, what does that mean

A

this means they are likely to be the same compound. this is not 100% guaranteed though.

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17
Q

if two substances do not have the same Rf value, what does that mean

A

they are 100% not the same compound

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18
Q

can a Rf value be over 1

A

NO, NOT EVER WILL THE Rf VALUE BE OVER 1

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19
Q

how many types of substances are there

A

there are 2 main types of substances: mixtures and pure substances

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20
Q

what is a pure substance

A

a substance where all the particles are the same

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21
Q

what is a mixture

A

a substance with different types of particles which are not chemically bonded together

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22
Q

how do you test if a substance is pure or not

A

you need to check if the melting or boiling point of a substance is exact.

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23
Q

what is the difference in melting or boiling points of a pure substance and a mixture

A

a pure substance melts at exact points while mixtures boil/melt at a range of temperatures

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24
Q

what is a formulation

A

a mixture which has been designed to produce a useful product

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25
Q

what does impurities do in a pure substance

A

they tend to lower the melting point and increase the boiling point

26
Q

what are 3 examples of formulations

A

alloys, fertilisers and medicines

27
Q

what is the test to test for hydrogen gas. list the steps

A

squeaky pop test
1. in a boiling tube add 3cm cubed of hydrochloric acid
2. add a piece of magnesium ribbon into the boiling tube an quickly cover the tube with a bung
3. 20 seconds later get a burning splint and remove the bung and instantly hold it at the mouth of the tube
4. the lighted splint should pop

28
Q

what is the test for carbon dioxide gas. list the steps

A

lime water turns cloudy
1. add 3cm cubed of lime water to a boiling tube
2. get another boiling tube which has a delivery tube attached and add 4cm cubed of hydrochloric acid
3. add a spatulas worth of sodium carbonate into the boiling tube with hydrochloric acid.
4. cover the top with a bung attached to a delivery tube and pass the gas into the limewater in the boiling tube.
5. the lime water should turn cloudy

29
Q

what is the test for oxygen gas. list the steps

A

glowing splint re-lights
1. add 5cm cubed of hydrogen peroxide into a boiling tube
2. add half a spatula of magnesium dioxide into the boiling tube
3. light a splint and gently blow it so that it is glowing but has no flame.
4. hold that splint at the mouth of the boiling tube. the splint should re-light

30
Q

how do you test for chlorine gas. list the steps

A

damp litmus paper test
1. hold a piece of the damp litmus paper in the gas
2. if it goes white (bleached) then it is chlorine gas

31
Q

how can you test for positive metal ions

A
  1. by adding sodium hydroxide solution
  2. flame test
32
Q

what metal ions can be tested by the flame test

A

lithium 1+
sodium 1+
potassium 1+
calcium 2+
copper 2+

33
Q

what flame does lithium 1+ produce

A

crimson

34
Q

what flame does sodium 1+ produce

A

yellow

35
Q

what flame does potassium 1+ produce

A

lilac

36
Q

what flame does calcium 2+ produce

A

orange-red

37
Q

what flame does copper 2+ produce

A

blue

38
Q

how do you setup a flame test

A
  1. Dip the nichrome loop in hydrochloric acid to clean
  2. put the nichrome loop into the flame of a Bunsen burner to clean
  3. dip the loop back into acid
  4. put the loop into the metal compound
  5. put the loop into the flame of the Bunsen burner
  6. record the flame colour change in a table and repeat the test
39
Q

what metal ions work with the sodium hydroxide test

A

copper 2+
iron 2+
iron 3+
calcium 2+
magnesium 2+
aluminium 3+

40
Q

what is another name for positive metal ions

A

cations

41
Q

how do you setup a sodium hydroxide test

A
  1. add 1cm cubed of the cation to a test tube
  2. add 2cm cubed of sodium hydroxide to the test tube
  3. observe and record any changes
  4. further add 5cm cubed of sodium hydroxide
  5. observe and record any changes
42
Q

what precipitate forms when copper 2+ is added to sodium hydroxide

A

blue precipitate

43
Q

what precipitate forms when iron 2+ is added to sodium hydroxide

A

light green precipitate

44
Q

what precipitate forms when iron 3+ is added to sodium hydroxide

A

brown precipitate

45
Q

what precipitate forms when calcium 2+ is added to sodium hydroxide

A

white precipitate

46
Q

what precipitate forms when magnesium 2+ is added to sodium hydroxide

A

white precipitate

47
Q

what precipitate forms when aluminium 3+ is added to sodium hydroxide

A

white precipitate

48
Q

what observations is made with excess sodium hydroxide

A

only 1 chemical reacts the others don’t. aluminium 3+ forms a white precipitate which then dissolves in excess sodium hydroxide

49
Q

what is the test for negative ions

A
  1. carbonate test
  2. sulphate test
  3. halide test
50
Q

what are negative ions also known as

A

anions

51
Q

how do you setup a carbonate test for anions

A
  1. place 1cm cubed of the sodium solutions into separate test tubes
  2. add 2cm cubed of lime water into a separate test tube
  3. add 1cm cubed of hydrochloric acid into each sodium solution test tube
  4. if there is effervescence then collect the gas using a pipette
  5. place the gas into the lime water and if it turns cloudy then it is C02 gas
52
Q

how do you set up a sulphate test for anions

A
  1. add 1cm cubed of sodium solutions into separate test tubes
  2. add a few drops of hydrochloric acid into each test tube
  3. then add 1cm cubed of barium chloride solution to each test tube
  4. a white precipitate should form if sulphate is present
53
Q

how do you setup a halide test for anions

A
  1. add 1cm cubed of the sodium solutions into separate test tubes
  2. add a few drops of dilute nitric acid to each test tube
  3. add 1cm cubed of silver bitrate solution
  4. chloride should form a white precipitate, bromide should form a cream precipitate and iodide should form a yellow precipitate
54
Q

what are qualitative methods of tests

A

tests which use observations

55
Q

what are quantitative methods of tests

A

tests which rely on measurements

56
Q

what does instrumental methods for analysis rely on

A

machinery

57
Q

what are the advantages of instrumental methods of analysis

A
  • rapid
  • very sensitive
  • accurate
  • can be used on very small samples
58
Q

what are the disadvantages of instrumental methods of analysis

A
  • equipment is expensive
  • equipment can only be used by specialists
  • gives results that can often be interpreted only by comparison with data from known substances
59
Q

what is flame emission spectroscopy used for

A

analysing metal ions in solutions

60
Q

how does flame spectroscopy work

A
  1. the sample is placed into a flame
  2. the light given out is passed through a spectroscope
  3. the light is analysed once passed through the spectroscope
  4. each element emits different light so the compound is split up into the different colours made by the elements in the ion and can be used to measure their concentration.

CHEMISTRY (12 decks)

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