acid-base titration Flashcards
method
add measured volume of one solution into conical flask using pipette
add another solution to burette - record initial reading
add drops of a single indicator
add the solution in the burette into the flask - dropwise
when the indicator changes colour - end point
record final burette reading
repeat until concordant results
how to use this method to identify a carbonate
prepare a solution of unkown carbonate in a volumetric flask - need to weigh the mass
pipette 25 cm3 into conical flask
titrate against acid
use molar ratios to find Mr
errors
forcing all the liquid out of the pipette
solution not mixed
cant see colour change
fix errors
do not force all liquid out of the pipette - it is calibrated to account for the liquid that remains in the pipette
swirl the flask during titration
use a white tile
2 indicators and their colour change
phenolphthalein - colourless in acid + pink in alkaline
methyl orange - red in acid + yellow in alkaline
what degree of precision should a burette be recorded to
nearest 0.05 cm^3
what 3 things are required to make an accurate burette reading
- read from bottom of meniscus
- allow any liquid on walls of burette to settle before taking a reading
- ensure no airbubbles
