Acid base

Question 1

Brønsted–Lowry acid and base

Answer 1

• Proton donor
• Proton acceptor

Question 2

Buffer solution.

Answer 2

Solution which resists change in pH when small amounts of acid or base are added

Question 3

How can we obtain a pH curve for a titration involving a acid in the conical

Answer 3

• Measure pH of the acid
• Add alkali in known small portions
• Stir mixture
• Measure pH after each addition
• Repeat until alkali in excess
• Add in smaller increments near endpoint

Question 4

Strong acid and Weak acid

Answer 4

• Completely dissociated
• Only slightly dissociated

Question 5

Explain how a buffer containing a weak acid HA and a NaA can act as a acidic buffer

Answer 5

• Large concentration of A- in buffer as NaA is completely ionised
• when extra H+ is acid ,it reacts with A–

equation: H⁺ + A^– → HA
* ratio [HA]/[A-] stays almost constant

Question 6

Why does a buffer solution change if left in air?

Answer 6

• CO_2, an acidic gas** present in **air
• pH decreases
• CO₂ + 2OH^– → CO₃ ^2– + H₂O

Question 7

Why is solution X weakly alkaline

Answer 7

• little OH^– formed so low [OH^–]

Question 8

Why doesn’t Kw formula include the concentration of water?

Answer 8

• [H₂O] is very high compared with [H+] and [OH–]
• [H₂O] is effectively constant