AQA A-Level Chemistry - Practicals.
Study online at https://quizlet.com/_3inifn
1. (1) Outline how to 1. All apparatus rinsed with distilled water.
prepare a Stan-
dard Solution in a 2. Solute weighed out accurately, on a weighing boat, using a balance accurate to
Volumetric Flask 2 dp.
(for an acid-base
3. Solid placed in beaker and dissolved in about 100cm3 of water.
titration).
4. Weighing boat rinsed with a small quantity of water and washings added to
beaker - or, weighing boat should be reweighed and the difference calculated.
5. Solution transferred to a 250cm3 volumetric flask.
6. Beaker rinsed with distilled water and washings added to volumetric flask.
7. Distilled water added to volumetric flask until made up to graduation mark -
bottom of meniscus should rest on the mark.
- If mark overshot, solution is more dilute than expected => start again.
8. Volumetric flask then inverted 20 times to ensure thorough mixing.
2. (1) Outline how 1. All apparatus rinsed with distilled water and then with the relevant solution.
to carry out an
acid-base titra- 2. Using a pipette and pipette filler, pipette 25cm3 of NaOH into a conical flask.
tion. Touch surface of solution with tip of pipette to ensure correct quantity is trans-
ferred.
3. Using a funnel, fill burette with acid and then remove funnel
- otherwise, some drops may fall through the titration after the initial reading has
been taken => lower volume recorded than used.
4. Allow a small quantity of the acid to flow through the burette to ensure jet space
is filled. Note initial reading on burette.
, AQA A-Level Chemistry - Practicals.
Study online at https://quizlet.com/_3inifn
- If jet space not filled, titre value higher than volume actually added.
5. Add 2-3 drops of phenolphthalein (or another suitable indicator) to the conical
flask and place it on a white tile - can see colour change better.
6. Add acid from burette into conical flask, swirling mixture during addition, until
indicator changes colour (pink ---> colourless).
7. During titration, rinse sides of conical flask with water ---> ensures all acid is in
solution.
8. Note the burette reading.
9. Repeat experiment but add acid dropwise (drop by drop) towards the end
point.
10. Continue repeating until at least two concordant results obtained (within
0.10cm3).
3. (1) Why do we use To see indicator colour change better.
a white tile?
4. (1) Why is a coni- Can be swirled without losing any solution.
cal flask used?
5. (1) Why is swirling To ensure that solutions mix and so react completely.
necessary?
6. (1) Why does rins- Water does not react ---> doesn't affect number of moles present.
ing the flask with
water not affect
the end point?
, AQA A-Level Chemistry - Practicals.
Study online at https://quizlet.com/_3inifn
7. (Other 1) Outline 1. Crucible weighed on a balance and its mass is recorded (mass 1).
how to carry out a
mass change ex- 2. Some sample placed in the crucible.
periment.
3. Crucible and contents reweighed on a balance and its mass recorded (mass 2).
4. Sample heated strongly in Bunsen.
5. Crucible and contents reweighed on a balance and its mass recorded.
6. The sample heated and reweighed until mass no longer changed ---> ensures
reaction completed.
8. (Other 1) Outline Include:
apparatus - dia-
gram. - Bunsen.
- Tripod.
- Pipe-clay triangle.
- Crucible.
- Lid.
- HEAT.
9. (Other 1) What 1. Formulae determination.
things would we
use mass change 2. Water of crystallisation.
experiments for?
3. Decomposition.
10. (Other 1) How Heat until constant mass.
can we ensure
that the (mass
change) experi-
ment has gone to
completion?
Study online at https://quizlet.com/_3inifn
1. (1) Outline how to 1. All apparatus rinsed with distilled water.
prepare a Stan-
dard Solution in a 2. Solute weighed out accurately, on a weighing boat, using a balance accurate to
Volumetric Flask 2 dp.
(for an acid-base
3. Solid placed in beaker and dissolved in about 100cm3 of water.
titration).
4. Weighing boat rinsed with a small quantity of water and washings added to
beaker - or, weighing boat should be reweighed and the difference calculated.
5. Solution transferred to a 250cm3 volumetric flask.
6. Beaker rinsed with distilled water and washings added to volumetric flask.
7. Distilled water added to volumetric flask until made up to graduation mark -
bottom of meniscus should rest on the mark.
- If mark overshot, solution is more dilute than expected => start again.
8. Volumetric flask then inverted 20 times to ensure thorough mixing.
2. (1) Outline how 1. All apparatus rinsed with distilled water and then with the relevant solution.
to carry out an
acid-base titra- 2. Using a pipette and pipette filler, pipette 25cm3 of NaOH into a conical flask.
tion. Touch surface of solution with tip of pipette to ensure correct quantity is trans-
ferred.
3. Using a funnel, fill burette with acid and then remove funnel
- otherwise, some drops may fall through the titration after the initial reading has
been taken => lower volume recorded than used.
4. Allow a small quantity of the acid to flow through the burette to ensure jet space
is filled. Note initial reading on burette.
, AQA A-Level Chemistry - Practicals.
Study online at https://quizlet.com/_3inifn
- If jet space not filled, titre value higher than volume actually added.
5. Add 2-3 drops of phenolphthalein (or another suitable indicator) to the conical
flask and place it on a white tile - can see colour change better.
6. Add acid from burette into conical flask, swirling mixture during addition, until
indicator changes colour (pink ---> colourless).
7. During titration, rinse sides of conical flask with water ---> ensures all acid is in
solution.
8. Note the burette reading.
9. Repeat experiment but add acid dropwise (drop by drop) towards the end
point.
10. Continue repeating until at least two concordant results obtained (within
0.10cm3).
3. (1) Why do we use To see indicator colour change better.
a white tile?
4. (1) Why is a coni- Can be swirled without losing any solution.
cal flask used?
5. (1) Why is swirling To ensure that solutions mix and so react completely.
necessary?
6. (1) Why does rins- Water does not react ---> doesn't affect number of moles present.
ing the flask with
water not affect
the end point?
, AQA A-Level Chemistry - Practicals.
Study online at https://quizlet.com/_3inifn
7. (Other 1) Outline 1. Crucible weighed on a balance and its mass is recorded (mass 1).
how to carry out a
mass change ex- 2. Some sample placed in the crucible.
periment.
3. Crucible and contents reweighed on a balance and its mass recorded (mass 2).
4. Sample heated strongly in Bunsen.
5. Crucible and contents reweighed on a balance and its mass recorded.
6. The sample heated and reweighed until mass no longer changed ---> ensures
reaction completed.
8. (Other 1) Outline Include:
apparatus - dia-
gram. - Bunsen.
- Tripod.
- Pipe-clay triangle.
- Crucible.
- Lid.
- HEAT.
9. (Other 1) What 1. Formulae determination.
things would we
use mass change 2. Water of crystallisation.
experiments for?
3. Decomposition.
10. (Other 1) How Heat until constant mass.
can we ensure
that the (mass
change) experi-
ment has gone to
completion?
