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CHEMISTRY GCSE > PAPER 2 REQUIRED PRACTICALS > Flashcards

PAPER 2 REQUIRED PRACTICALS Flashcards

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1
Q

rate of reaction

A

use a measuring cylinder to put 10cm3 of sodium thiosulfate solution into a conical flask
place conical flask onto printed black cross
add 10cm3 of HCL into conical flask
swirl solution and start stopwatch
look down into flask after a certain time the solution will turn cloudy, stop the stopwatch when you can no longer see the cross
repeat experiment again using lower concentrations of sodium thiosulphate solution
repeat whole experiment and calculate mean values for each concentration of the sodium thiosulphate solution

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2
Q

what shouldn’t you do when working out the mean values

A

use anomalies

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3
Q

problems with the rate of reaction

A

people have different eyesight that means that some people can see the cross for longer than others
however all the students use the same size cross

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4
Q

volume of a gas from reaction

A

use measuring cylinder to place 50cm
attach conical flask to a bong and delivery tube
place an upturned measuring cylinder filled with water over the delivery tube
add 3cm strip of magnesium to the hcl and start stopwatch
the reaction produces hydrogen gas which is trapped in the measuring cylinder
every 10 seconds measure volume of hyderogen gas in measuring cylinder until no hydrogen is given off
repeat experiment using different concentrations of HCL

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5
Q

what do both rate of reaction experiemts show

A

the greater the concentration of a chemical in a reaction the faster it takes place

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6
Q

paper chromatography

A

use a ruler to draw horizontal line on paper it should be 2cm from the bottom of the paper
mark pencil spots at equal spaces across the line
put the spots on the line using a capillary tube
pour water in beaker- attack paper to glass rod with selotape and dip the paer into water
make sure that the line is above the surface of the water so that the ink doesn’t wash off
use a pencil line to mark where water reached
compare the different colourings with the unkniwn colour

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7
Q

things to watch when doing paper chromatography

A

pencil line above surface of water
sides of the paper shouldn’t touch the sides of the beaker if this happens it will interfere with the way the water moves
lid to reduce the evaporation of the solvent

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8
Q

how do you work out rf value

A

distance moved by solvent

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9
Q

what does rf value tell you

A

the identity of the chemical

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10
Q

flame tests

A 
lithium-crimson
sodium- yellow
potassium- lilac
calcium- orange/red
copper-green
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11
Q

lithium flame test

A

crimson

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12
Q

sodium flame test

A

yellow

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13
Q

potassium flame test

A

lilac

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14
Q

calcium flame test

A

orange/red

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15
Q

copper flame test

A

green

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16
Q

barium flame test

A

green

17
Q

problems with the flame test

A

colour of flame test can be difficult to distinguish
if there is a low concentration of the metal compound
sometimes a sample contains a mixture of metal ions which mask the colour of the flame

18
Q

copper ii ions reaction with sodium hydroxide

A

blue precipitate of copper hydroxide

19
Q

iron ii ions reaction with sodium hydroxide

A

green precipitate of iron hydroxide

20
Q

iron iii ions reaction with sodium hydroxide

A

brown precipitate of iron hydroxide

21
Q

why are instrumental methods eg spectroscopy better than flame tests

A

you can analyse samples more rapidly than you could with flame tests

they are more sensitive flame emission spectroscopy will work even on a tiny sample of metal compound

instrumental methods are accurate, flame emission spectroscopy is more likely to identify a metal ion correctly than using a flame test

22
Q

non metal ions

A

carbonate
halides
sulfate

23
Q

test carbonate

A

add nitric acid to sample
the acid will react with the carbonate to make co2 gas we will see effervescence
bubble the gas through limewater, if the limewater goes cloudy this proves we have carbon dioxide

24
Q

test for halides

A

add dilute nitric acid to sample then add dilute silver nitrate solution
halide ions produce a precipitate of silver halide. each halide makes a different coloured precipitate

25
Q

the colour for the chloride precipate

A

white precipitate of silver chloride

26
Q

the colour bromide precipate

A

cream precipitate pf silver bromide

27
Q

the colour for the iodine precipate

A

yellow precipitate of silver iodide

28
Q

test for sulphates

A

add dilute hcl to sample
add barium chloride solution
if sulfate ions are present we will see white precipitate

29
Q

calcium ions reaction with sodium hydroxide

A

white precipitate of calcium hydroxide

30
Q

aluminium ions reaction with sodium hydroxide

A

white precipitate at first, but then redissolves in excess NaOH to form a colourless solution

31
Q

magnesium ions reaction with sodium hydroxide

A

white precipitate

32
Q

how to do the flame test

A

first clean a platinum wire loop by dipping it in some dilute HCL and then holding it in a blue flame from a Bunsen burner until it burns without any colour
then dip the loop into the sample you want to test and put it back in the flame, record the colour of the flame

33
Q

distilled water

A

given an sample water
check ph of water by placing a small amount of the water onto a piece of universal indicator paper

if ph of water isn’t 7 then the water sample contains dissolved acid or alkali and is therefore not pure

use balance a weigh an empty evaporating balance and record mass
fill evaporating basin with water sample and place this on a tripod and gauze
use Bunsen burner to gently heat the water until it has all evaporated allow the basin to cool then weigh it again if the basins weight increased that means that there were dissolved solids in the water, these dissolved solids would’ve created crystal which increases the mass on the evaporating basin

if it didn’t increase the water didn’t contain any dissolved solids and the water was pure

34
Q

how to purify water by distillation

A

put water sample inside a conical flask, put the conical flask on a tripod and a gauze
the top of the conical flask has a delivery tube and this is pointing into a test tube
the tt is sitting in a beaker containing ice and water
gently heat the water using a Bunsen burner
water will evaporate and form water vapour, the water vapour now travels along a collecting tube
when the water vapour enters the cold test tube it condenses back into liquid water,
this is distillation

CHEMISTRY GCSE (13 decks)

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