Topic 12- Acid Base Equilibria

Question 1

Define a Bronsted-Lowry acid

Answer 1

a proton donor

Question 2

Define a Bronsted-Lowry base

Answer 2

A proton acceptor

Question 3

Define a buffer solution

Answer 3

A solution made up of large amounts of weak acid and conjugate base to resist pH changes when small volumes of H+ and OH- are added.

Question 4

In the reaction of propanoic acid and sodium propanoate, why is the equivalence point not at 7?

Answer 4

At equivalence point, propanoate ions are present
-the propanoate ions react with water molecules and form OH- ions
-hence increasing the pH
propanoate ions + water = OH- ions + propanoic acid

Question 5

Define enthalpy change of neutralisation

Answer 5

the enthalpy change when an acid neutralises an alkali to form one mole of water under standard conditions

Question 6

How does buffer action work in the blood?

Answer 6

Carbonic acid and hydrogencarbonate form an equlibrium reaction within the blood
-adding alkali shifts equilbrium to the right as water is formed
-adding acid shifts equilibrium to the left as carbonic acid is formed
Overall equation: H2CO3(aq) ⇌ H+(aq) + HCO3–(aq)