Question

1) Explain what a high Ka value of an acid represents and what a low Ka value represents.

2) State and explain the difference between the endpoint and the equivalence point in a titration.

Answer 1

Q1

Ka is a measurement of dissociation in equilbirium of an acid

HA <-> H+ + A-

Ka = [H+][A-]/[HA]

therefore

large values of Ka, implies high dissociation, i.e. strong acid

low vlaues of Ka implise low dissociation, i.e. weak acids

therefore

this help us compare acidity between species

Q2

endpoint --> typically, the point in which we assume the equivalnec epoint has been achieved, it is marked by a change in pH / change in color if indicator is used

the equivalnece point --> the exact point in which mol of acid = mol of base, which is hard to achieve with 100% precision due to amounts of 10^-x being used

In lab, we approximate the end point to the equivalence point