practicals titration Flashcards
Why is it important to remove any air bubbles from the burette tap?
The volume of the air bubble would be counted in the burette reading
If the bubble was not removed from the burette tap, how would this affect the titre?
Increase it
Why is it important to remove the funnel used to fill up the burette before starting a titration?
Solution drops could fall from the funnel into the burette and affect the burette reading
- Why is it good practice to swirl the conical flask and rinse the walls of the conical flask with distilled water during a titration?
Ensures all reactants mix and no reagent is left unreacted on sides of flask
Why does adding water to the conical flask not affect the titre?
It doesn’t change the number of moles in the conical flask
What should the burette be washed with before a titration?
Whatever solution it is going to be filled with
Why is it bad practice to wash the burette with water before a titration?
Water would decrease the concentration of the solution in the burette, which would increase the titre
What should the pipette used to fill up the conical flask be washed with?
Whatever solution is going to be put in the conical flask
Why is it bad practice to wash the pipette with water before using it to fill up the conical flask?
Water would take up space in pipette and decrease the number of moles transferred to the conical flask, which would reduce the volume needed from the burette (titre) for complete reaction
Making up a standard (volumetric) solution
a) Weigh the sample bottle containing the solid on a (2 dp) balance
b) Transfer to beaker* and reweigh sample bottle
c) Record the difference in mass
a) Add distilled / deionised water
b) Stir (with a glass rod) or swirl
c) Until all solid has dissolved
a) Transfer to volumetric / graduated flask using a funnel
b) With washings
c) Make up to 250cm3 / mark with water
d) Shakes/inverts/mixe
Percentage error =
Error of the equipment x100%
/
Amount measure
