4.2 - Acid Base Titrations Flashcards
What apparatus is used In a titration to accurately measure volumes?
- burette- measure the volume of solution added
- pipette and pipette filler - to measure a specific volume of solution into the conical flask
Describe how to carry out an acid-base titration
- Use a pipette to add 25cm^3 of acid to a conical flask
- Add a few drops of indicator
- Pour alkali into the burette
- Record the initial volume of the burette
- Complete a trial titre- the conical flask should be swirled constantly above a white tile
- Stop adding the alkali as soon as the end point is reached
- Record the final burette volume
- Repeat the titration until two concordat results are obtained
- Add alkali drop by drop near the end point
When transferring a solution from one beaker to another, how can you ensure as much of the dissolved substance has been transferred as possible?
Use distilled water to wash any left over solution from the old apparatus into the new beaker
How do you accurately fill a volumetric flask to the graduated mark?
-Fill so the bottom of the meniscus rests on the graduated mark
- the meniscus is the curve of the liquid
Define standard solution
A solution of a known concentration
Suggest 2 indicators that could be used in an acid-base titration
- Phenolphthalein
- Methyl orange
State the colour ofphenolphthalein in:
a) acidic conditions
b ) basic conditions
A) pink
B ) colourless
State the colour of methyl orange in
A ) acidic conditions
B ) basic conditions
A) Red
B ) yellow
( orange at the end point of a titration )
What are concordant results?
Titres that are within 0.10cm^3 of each other
What degree of precision should burette readings be recorded to?
Nearest 0.05cm^3
Why is a conical flask swirled during a titration?
To ensure all the reactants are combined so that the reaction is complete
Why is it better to have a titre volume of 25cm^3 than 10cm^3 ?
Larger the titre volume = smaller % error
