Unit 2 Assignment A - Part 1 and Part 2 of Overview of a Titration
5 views 0 purchase
Course
Unit 2 Assignment A
Institution
PEARSON (PEARSON)
Part 1 and 2 combined. no plagiarism of spelling errors. in depth and clear. marked learner work. overview of a titration in the BTEC course Applied Science.
The purpose of a titration is to determine an unknown concentration of a solution, and to do so a
standard solution (know concentration) must be included for the complete procedure to have
accurate results. It is a neutralisation reaction meaning an acid and alkali (base) will be titrated to
one another. (1)
Equipment required:
-three clean conical flasks (250cm3)
-a calibrated burette (with burette stand and a clamp)
-volumetric glass pipette
-pipette filler (rubber bulb pipette filler)
-a suitable indicator (e.g. phenolphalein)
-funnel
-distilled water
-solutions, both standard and unknown (e.g. hydrochloric acid for standard)
1.attach a pipette filler (preferably rubber bulb one) on the end of the calibrated glass pipette
2.press the appropriate button (A valve) on the pipette filler and gently squeeze to expel air (until
the bulb ‘caves in’ on itself)
3.place the tip of the glass pipette into the unknown solution and press appropriate button again to
draw up solution (make sure no air bubbles are affecting the volume)
4.take more solution than intended (over the line which represents 25cm 3) to then press the E valve
to slowly empty the solution in a controlled manner until the bottom of the meniscus (U shape) is
touching the line
5.then place the tip of the pipette over a conical flask to hold the contents once releasing the
solution, this is done by holding down the E valve on the rubber bulb filler
,6.once all of the solution is in the conical flask, ‘kiss the surface’ by gently putting the end of the
pipette in the released solution to collect any remaining solution
How to use a burette:
1.clamp the burette to the burette stand to keep it in place (do this on a stool instead of a table so
the equipment is eye level and in arms reach)
2.place a funnel in top of the burette and pour in the standard solution making sure to slightly
elevate the funnel to ensure nothing spills out (make a note of the reading on the burette for later),
may also use a Pasteur pipette to transfer small amounts of solution in order to get an accurate
volume within the burette
3.add a few drops of indicator into the conical flask holding the unknown concentration (2-3 drops,
e.g. phenolphalein)
4.place flask under the burette on a white tile (to view colour change better/end point) and add
solution by twisting the tap horizontally, start off with a slow stream until there is a slight colour
change then adjust the tap so only drops are coming out (this ensures an accurate end point) do this
until a permanent colour change occurs
5.record final burette reading to work out the volume of the solution which was added from the
burette (work this out by a simple subtraction to find the titre from the initial and end point)
How to read a burette:
-make sure your eye is the same level as the meniscus to avoid an error
-all burette readings are given to an accuracy of 0.05ml
-the meniscus is a concave shape (U shape), read the centre and not the sides (bottom of the
meniscus)
(13)
method of titration only:
1.start off by running a rough titration in order to get a rough end point for better accuracy and
timing when carrying out the other titrations (to evaluate amount of standard solution required and
when to expect the end point)
, 2. before beginning, glassware must be rinsed with appropriate solutions, 5cmmhrough conical flask,
volumetric pipette, and beaker then 10cmmhrough the burette, this gets rid of air bubbles, ensures
the equipment is accurate and cleans it (no other substances inside)
3.complete the ‘how to use a volumetric glass pipette’ method which has been explained previously
4.then complete the ‘how to use a burette’ method which has been explained previously
5.after this record all the results down on to a table and repeat this same titration another 2-3 times,
this allows you to gather concordant results and exclude any anomalies, having an accurate end
result
-can drop a similar amount of volume identified by the rough titration first until there is a slight
colour change, then start dripping the solution from the burette tap
Rough titration:
-purpose is to get a rough measurement of standard solution and when to predict an end point
1.before beginning, glassware must be rinsed with appropriate solutions, 5cm through conical flask,
volumetric pipette, and beaker then 10cm through the burette, this gets rid of air bubbles, ensures
the equipment is accurate and cleans it (no other substances inside)
2.do the method of a titration (explained above) however the method differs when the standard
solution is being filled into the unknown solution through the burette
3. record the measurement of the meniscus in the burette before letting any solution gets out,
should be roughly 25cm3
4.then twist the tap horizontally to let out a consistent stream of standard solution
5.when a slight colour change is identified start letting in tiny amounts of solution (but not dripping
it) in at a time until at the end point
6.record the measurement of the meniscus now and do a simple subtraction to find out the rough
amount of standard solution needed to reach the end point; this helps with the following titrations
as there is an estimated measurement
(5)(6)
After running a rough titration to predict the end point, 3-4 more accurate titrations must be
completed in order to produce concordant results (no anomalies). This ensures the procedure has
been done sufficiently each time, that the equipment is accurate and also gives an average result for
all the experiments combined.
The benefits of buying summaries with Stuvia:
Guaranteed quality through customer reviews
Stuvia customers have reviewed more than 700,000 summaries. This how you know that you are buying the best documents.
Quick and easy check-out
You can quickly pay through credit card or Stuvia-credit for the summaries. There is no membership needed.
Focus on what matters
Your fellow students write the study notes themselves, which is why the documents are always reliable and up-to-date. This ensures you quickly get to the core!
Frequently asked questions
What do I get when I buy this document?
You get a PDF, available immediately after your purchase. The purchased document is accessible anytime, anywhere and indefinitely through your profile.
Satisfaction guarantee: how does it work?
Our satisfaction guarantee ensures that you always find a study document that suits you well. You fill out a form, and our customer service team takes care of the rest.
Who am I buying these notes from?
Stuvia is a marketplace, so you are not buying this document from us, but from seller macyparsons06. Stuvia facilitates payment to the seller.
Will I be stuck with a subscription?
No, you only buy these notes for $16.11. You're not tied to anything after your purchase.
