Acid - Base Titrations Flashcards
What is a titration?
The experimental technique to finding the conc. of an unknown compund A through reaction with sol of compound B
How are the behaviours of a strong acid and weak acid titration curve different?
They result in different titration curves because even though they have essentially the same neutralisation reaction: H3O+ + OH- –> H2O
Strong acids dissociate completely into H3O+ ions which react with OH-
But weak acids only partly dissociate so there is an equilibrium
Resulting in different curves to be produced
Key features of a weak titration curve
Refer to paper
When is the end of the titration?
At the equivalence point when n(acid) = n(base) i.e the reaction is finished.
Why is there a sudden jump in pH on the titration curve of a weak A-B titration?
The no. of HA molecules drastically decrease and this causes the sudden spike in pH as the A- molecule cumber increases i.e it has reached it’s buffer capacity
What happens at the half equivalence point?
The concentration of HA = A-
Therefore, pH = pKa
At what point is the perfect buffer?
At the equivalence point
What happens if we add rogue acid to the buffer point and vice versa?
The pH decreases slightly but not by a lot (more acid to buffer initially means that equi suddenly shifts to the left)
And vice versa
What happens beyond the equivalence point?
The curve tries to reach its max point, but doesn’t fully due to the dilution factor on the base.
pH of eqivalence pts of strong acids?
7 as its proper neutralisation
What happens in a strong acid titration?
Strong acid completely dissociates, so the H+ completely reacts with added base to neutralise the sol
Diprotic acid
Will give two protons at once if possible
What is an amino acid?
Has a weak acid and base in the same molecule
Standard form of an amino acid
H2N — C (bonded to R and H) —COOH
What is the simplest form of the amine?
Glycine, where R group is subbed with an H
