C5d- Titrations Flashcards
What are titrations used for?
to find out concentrations of unknown reactants
What is the equation linking moles, concentration and volume?
Moles = concentration x volume
Interpret a PH curve which starts at ph 4 and ends at ph 12
an alkali has been added to an acid
What is the endpoint?
halfway down the vertical line
What is the equivalence point?
where the moles of acid is equal to the number of moles of alkali
What apparatus do you need in an acid base titration?
burette
conical flask
pipette
pipette filler
Why is it important to use a pipette filler?
to stop alkali getting in your mouth
What is the method for carrying out a simple acid base titration?
1) place the acid (or alkali) into a burette
2) place some alkali(or acid) into a conical flask using a pipette
3) add a suitable indicator (name it)
4) note the initial reading
5) add acid (or alkali) to the flask until the colour changes. Do this drop wise near the endpoint
6) note the final reading
7) repeat
What does concordant mean?
the same
What colour do litmus and phenolphthalein turn in alkali?
litmus - blue
phenolphthalein - red
What colour do litmus and phenolphthalein turn in acid?
litmus - red
phenolphthalein - colourless
Why should an acid base titration use a single indicator rather than a mixed one?
because you want a sudden colour change
25cm3 of 0.1 mol/dm3 NaOH is needed to neutralise 25cm3 of a solution of hydrochloric acid. How would you calculate the concentration of the acid?
1) find the known solution (the one with volume and concentration)
NaOH
2) calculate the number of moles of the ‘known’
0.100 x (25 ÷ 1000) = 0.0025
3)write down the number of moles of the ‘unknown’ (the same as known)
0.0025
4) Calculate the concentration of the unknown
conc = moles ÷ volume
0.0025 ÷ 25 = 0.0001
0.1mol/dm3
