Carrying out an acid base titration Flashcards
1
Q
How is the equipment prepared?
A
- rinsed
- rine burette with acid
- pipette with alkali
- conical flask with distilled water
2
Q
What is added to conical flask? How is it done?
A
- pipette 25cm3 of alkali into the conical flask
- touch surface of alkali with pipette
- to ensure the right amount is added
3
Q
What is added to burette? How is it done? What is recorded
A
- acid
- make sure jet space is filled with acid
- record initial burette reading
4
Q
How much indicator is added
A
few drops
5
Q
What must the flask be placed on ? why?
A
- white tile
- help observe colour change
6
Q
What must be done when the acid is being added to the alkali?
A
swirl mixture
7
Q
How are results obtained?
A
- add dropwise near end point
- estimate using rough value
- stop adding acid when colour change observed
- record final burette reading
- repeat titration until at least 2 concordant results are obtained
- two reading within 0.1 of each other
8
Q
What will happen if the jet space is not filled
A
obtain a larger value then expected
9
Q
Why are concial flasks used over beaks
A
easier to swirl
10
Q
why must only a few drops of indicator added?
A
indicators are usually weak acids
adding too much will affect result
11
Q
WHat are the two indicators used?
A
- phenopthalein
- pink (alkali) to colourless (acid)
- end point - pink colouir disappears
- use if NaOH used
- methyl organge
- yellow (alakli) to red (acid)
- end point orange
- use if HCl is used
12
Q
WHy do you need concordant results
A
reduce the effect of random error
calculate mean titre
13
Q
HOw is percentage uncertainty measured?
A
- instrument uncertainty / value measured x 100
