Determination of the concentration of ethanoic acid in vinegar by titration against standard sodium hydroxide solution Flashcards
(41 cards)
Apparatus
- Safety glasses
- Funnel
- Conical flask
- Pipette
- Burette
- 250cm3 volumetric flask
- Retort stand
- Wash bottle of deionised water
- White tile
Materials
- 0.1M NaOH
- Vinegar
What is the first step (method)
The pipette, burette and conical flask were rinsed with deionised water to clean them.
What happens after the pipette, burette and conical flask were rinsed (2nd step)?
25cm3 of the vinegar were diluted to 250cm3 in the volumetric flask.
What was the dilution factor?
10
Why did the vinegar need to be diluted? (L.C)
Original vinegar would be too concentrated and would require an excessive amount of sodium hydroxide to react with it.
What happened after the vinegar was diluted in the volumetric flask?
The pipette was washed with some of the DILUTED vinegar.
Why was the pipette washed with diluted vinegar?
To prevent further dilution of the solution.
What happened after the pipette was washed?
25cm3 of the diluted vinegar were transferred to a clean dry conical flask observing the usual precautions.
Is acid usually placed in the conical flask?
No (but is in this experiment)
What was added to the conical flask after the diluted vinegar?
2-3 drops of phenolphthalein indicator
What colour is phenolphthalein in acid solution?
Colourless
What happened after the indicator was added?
The burette was washed with the sodium hydroxide solution.
Why was the burette washed with the sodium hydroxide solution?
To prevent a change in concentration.
Is the base usually placed in the burette?
No
Is the base placed in the burette in THIS experiment?
Yes
What is the base in this experiment?
NaOH solution
What happened after the burette was washed with the solution?
The burette was filled with the NaOH solution observing the usual precautions and was clamped vertically.
What happened after the burette was filled with NaOH solution and clamped vertically?
The conical was placed on a white tile and the titration was carried out observing the usual precautions until a colour change occurs.
What is the colour change that is seen?
Colourless to pink
What happened after the first titration is over?
The titration was repeated two more times more accurately.
When is the titration over?
When the solution changes to pink.
What was cleaned when the titration was done?
The burette was washed out thoroughly.
Why was the burette washed out thoroughly at the end?
To prevent the base from clogging up the tap.
