CGIER 41 - Buffer system and Henderson-Hasselbalch equation

Question 1

henderson-hasselbalch equation

Answer 1

pH = pKa + log(Conjugate base/weak acid)
pH = pKa + log [Ionised or deprotonated acid]/[unionised]

Question 2

CH3COOH(Acetatic acid) + H2O

Answer 2

CH3COO-(Acetate ion) + H3O+

Question 3

when does the best buffering occur

Answer 3

when [acid] = [conjugate base] equal amounts

can with stand changes upon addition of acids and bases to equal extent

Question 4

useful buffer range

Answer 4

pKa +/-1

Question 5

find an acid that will give good buffering of pH 4

Answer 5

look at list of weak acids
find their pKa and find which one is the closest to 4
closer to 4 greater chance one will have equal amounts of weak acid and conjugate base

Question 6

the greater the amounts of conjugate acid base pair…..

Answer 6

the more resistant they are to change in pH

Question 7

How does concentration influence buffering capacity and what does that mean

Answer 7

greater concentration - greater buffering capacity

if a solution of different concentration and pH was added it wouldn’t make a vast difference in the solutions pH