5/28/25, 4:47 PM AQA A LEVEL CHEM PRACTICALS - PAPER 3 Flashcards | Quizlet
AQA A LEVEL CHEM PRACTICALS - PAPER Save
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Enzymes specimen 2015 paper 1 Transition metals 2018 GC
23 terms 8 terms 24 terms 31 terms
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Terms in this set (35)
The standard cell potential is the e.m.f. between two half cells making up the
cell, measured under standard conditions.
clean piece of each metal, e.g. copper and zinc. degrease using propanone,
place copper in a beaker with around 50cm₃ 1moldm⁻³ copper sulfate
solution, place zinc in a seperate beaker of same concentration and volume
zinc sulfate solution
measuring e.m.f. of electrochemical
join the two beakers with filter paper coated in NaCl/potassium nitrate - acts
cells
as a salt bridge
connect one end to positive terminal of voltmeter and the other electrode to
the negative terminal, ensuring the reading is positive - if it is negative,
reverse the connections to the electrodes
record the reading of the voltmeter, writing which electrode is connected to
the positive and negative terminals
- place a known mass of a sample in a beaker, add 100cm³m of distilled water
to beaker to dissolve sample, record mass to 2 d.p.
- use a glass rod to stir
- pour this solution into a graduated flask via a funnel
standard solution - rinse beaker and funnel using distilled water and add washings to volumetric
flask
- make up to the mark with distilled water so that the meniscus sits on the
line
- invert flask several times to ensure uniform solution
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, 5/28/25, 4:47 PM AQA A LEVEL CHEM PRACTICALS - PAPER 3 Flashcards | Quizlet
- rinse burette with deionised water and then with the solution you're using
- fill the burette past the mark (using funnel) and empty the burette until
meniscus is on the line
- removal funnel so no more solution can enter
- rinse pipette with deionised water and then with the solution you're using.
when filling pipette go past the line then empty until meniscus is on the line
-rinse conical flask with deionised water
Titration - known concentration in - pipette 25cm³ of required solution into conical flask
burette, unknown concentration in - add required indicator
conical flask - swirl to mix
- titrate the solution from the burette, about 1cm³ at a time, until indicator
changes colour
*any drops or splashes up the side of the flask should be washed with
deionised water
*repeat titration adding solution dropwise when reaching end point - record
all to 2.d.p but only ending in 0 or .5 repeat until results are concordant
(within .1)
may lose some solution before it starts
don't remove funnel so some drops fall during titration
What may go wrong with titration? may rinse conical flask with solution so you have added more solution to the
flask
may not include all of the washings
strong acid - strong base = either methyl orange or phenolphthalein ( pink to
colourless)
weak acid - strong base = phenylphthalein, strong acid - weak base = methyl
Which indicator should be used?
orange ( yellow to red/orange)
Indicator must change sharply at the equivilance point, so the pH range of the
indicator should fall within the 'vertical section' (region of rapid pH change)
solution of alkali of known concentration added from a burette to a measured
What happens in an acid-base titration amount of an acid. indicator used to find end point - from volume of base
required, concentration of acid can be calculated
titrate the aq solution, with known volume in a conical flask and acid in
burette, repeat titration until concordant results found.
How can number of molecules of water
Use added volume to work out moles using molar ratio.
of crystallisation be determined in a
calculate mr using known mass and number of moles found - then calculate
practical?
'x' using found mr - mr of each molecule in substance, divided by 18 to find
number of H2O molecules
- pipette 25cm³ acid and add indicatir, place beaker on a magnetic stirrer and
place magnet in the beaker, fill burette with base
- rinse electrode with distilled water as readings may have changed over time,
dip it into the acid in the beaker, recording pH
Acid-base titration -switch on stirrer and ensure magnet doesnt strike the electrode.
- add 5cm³ base and take readings of pH and indicator
- continue adding base taking 5cm³ readings each time then 1cm³ around end
point, then 5cm³ util most base has been added
- plot a graph of pH (Y axis) against volume of base added
https://quizlet.com/gb/302250142/aqa-a-level-chem-practicals-paper-3-flash-cards/ 2/7
AQA A LEVEL CHEM PRACTICALS - PAPER Save
3
5.0 (2 reviews) More
Students also studied
Flashcard sets Study guides
Enzymes specimen 2015 paper 1 Transition metals 2018 GC
23 terms 8 terms 24 terms 31 terms
teganbaileyyyy Preview hfdertyuyvb Preview hajsal777 Preview pee
Terms in this set (35)
The standard cell potential is the e.m.f. between two half cells making up the
cell, measured under standard conditions.
clean piece of each metal, e.g. copper and zinc. degrease using propanone,
place copper in a beaker with around 50cm₃ 1moldm⁻³ copper sulfate
solution, place zinc in a seperate beaker of same concentration and volume
zinc sulfate solution
measuring e.m.f. of electrochemical
join the two beakers with filter paper coated in NaCl/potassium nitrate - acts
cells
as a salt bridge
connect one end to positive terminal of voltmeter and the other electrode to
the negative terminal, ensuring the reading is positive - if it is negative,
reverse the connections to the electrodes
record the reading of the voltmeter, writing which electrode is connected to
the positive and negative terminals
- place a known mass of a sample in a beaker, add 100cm³m of distilled water
to beaker to dissolve sample, record mass to 2 d.p.
- use a glass rod to stir
- pour this solution into a graduated flask via a funnel
standard solution - rinse beaker and funnel using distilled water and add washings to volumetric
flask
- make up to the mark with distilled water so that the meniscus sits on the
line
- invert flask several times to ensure uniform solution
https://quizlet.com/gb/302250142/aqa-a-level-chem-practicals-paper-3-flash-cards/ 1/7
, 5/28/25, 4:47 PM AQA A LEVEL CHEM PRACTICALS - PAPER 3 Flashcards | Quizlet
- rinse burette with deionised water and then with the solution you're using
- fill the burette past the mark (using funnel) and empty the burette until
meniscus is on the line
- removal funnel so no more solution can enter
- rinse pipette with deionised water and then with the solution you're using.
when filling pipette go past the line then empty until meniscus is on the line
-rinse conical flask with deionised water
Titration - known concentration in - pipette 25cm³ of required solution into conical flask
burette, unknown concentration in - add required indicator
conical flask - swirl to mix
- titrate the solution from the burette, about 1cm³ at a time, until indicator
changes colour
*any drops or splashes up the side of the flask should be washed with
deionised water
*repeat titration adding solution dropwise when reaching end point - record
all to 2.d.p but only ending in 0 or .5 repeat until results are concordant
(within .1)
may lose some solution before it starts
don't remove funnel so some drops fall during titration
What may go wrong with titration? may rinse conical flask with solution so you have added more solution to the
flask
may not include all of the washings
strong acid - strong base = either methyl orange or phenolphthalein ( pink to
colourless)
weak acid - strong base = phenylphthalein, strong acid - weak base = methyl
Which indicator should be used?
orange ( yellow to red/orange)
Indicator must change sharply at the equivilance point, so the pH range of the
indicator should fall within the 'vertical section' (region of rapid pH change)
solution of alkali of known concentration added from a burette to a measured
What happens in an acid-base titration amount of an acid. indicator used to find end point - from volume of base
required, concentration of acid can be calculated
titrate the aq solution, with known volume in a conical flask and acid in
burette, repeat titration until concordant results found.
How can number of molecules of water
Use added volume to work out moles using molar ratio.
of crystallisation be determined in a
calculate mr using known mass and number of moles found - then calculate
practical?
'x' using found mr - mr of each molecule in substance, divided by 18 to find
number of H2O molecules
- pipette 25cm³ acid and add indicatir, place beaker on a magnetic stirrer and
place magnet in the beaker, fill burette with base
- rinse electrode with distilled water as readings may have changed over time,
dip it into the acid in the beaker, recording pH
Acid-base titration -switch on stirrer and ensure magnet doesnt strike the electrode.
- add 5cm³ base and take readings of pH and indicator
- continue adding base taking 5cm³ readings each time then 1cm³ around end
point, then 5cm³ util most base has been added
- plot a graph of pH (Y axis) against volume of base added
https://quizlet.com/gb/302250142/aqa-a-level-chem-practicals-paper-3-flash-cards/ 2/7
