pratical 1 AOS Flashcards
describe how to make up a standard solution
weigh the sample bottle containing the soild on a balance
transfer to the beaker and reweigh the sample bottle
record the difference in mass
add distilled water
stir
until all soild has dissolved
transfer to volumetric flask using a funnel
with washings
make up to 250cm^3 mark with water
shakes/inverts/mixes
what is a concordant result
results within 0.1cm^3 of each other
why is it important to remove any air bubbles from the burrette
volume of air bubble would be counted in the burette reading
if a 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 the titration
solution drops could fall from funnel into the burette and affect the reading
why is it good practice to swirl the conical flask and rinse the walls of the conical flask with distilled water during the titration
ensure all the reactants mix and no reagent is left unreacted on the sides of the flask
why does adding water to the conical flask not affect the titre
it doesnt change the number of moles in the conical flask
why should you use a conical flask over a beaker in a titration
less chance of splashing liquid whilst swirling
what should the burette be washed with before the titration
whatever solution its going to be filled with
what should the pipette used to fill up the conical flask be washed with
whatever solution is going in the conical flask
why is it bad practice to wash the burette with water before the titration
it would decrease the concentration of the solution in the burette increasing the titre
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 for complete titration
