CHEM 191 Lecture 6

Question 1

what is Ka a measure of

Answer 1

acid strength; the larger the value of Ka the more extensive the dissociation at equilibrium and the strong the acid

Question 2

what is Kb a measure of

Answer 2

base strength; the larger the value of Kb, the more extensive the formation of OH- at equilibrium and the stronger the base

Question 3

what does a small Ka or Kb mean

Answer 3

a weak acid or base

Question 4

what does a large pKa or pKb mean

Answer 4

a weak acid or base

Question 5

in all cases are Ka and Kb greater or lesser than 1

Answer 5

lesser than 1. Therefore the extent of dissociation of the weak acid or base in small in water

Question 6

Ka x Kb =

Answer 6

Kw (1x10^-14) at 25 degrees celsius

Question 7

pKa + pKb =

Answer 7

pKw (14) at 25 degrees celsius

Question 8

if you have a strong acid or base is it’s conjugate likely to be strong or weak

Answer 8

weak (pKa+pKb=pKw)

Question 9

iff you have a weak acid/base can you assume it’s conjugate base/acid is strong

Answer 9

no, in fact if you have a weak acid its conjugate base is likely to be weak as well

Question 10

how can transition metals compounds acts as weak acids

Answer 10

transition metal complexes are a class of molecule where molecules called ligands (lewis bases) form bonds to a transitional metal cation (lewis acid). when the ligands are water molecules the resulting complex can act as a base.