Titrations and Buffers

The buffer solution is able to maintain pH by some events, except . . .

• The addition of a little acid

• The addition of a little base

• Dilution

• Addition of water

• The addition of excess acid

The pH solution that consist of CH₃COOH 0.01 M and CH₃COONa 0.01 M with Ka = 10^-5 is . . .

• 4

• 5

• 6

• 8

• 9

Acidic buffer is made up of

• weak acid and weak base
• weak acid and its conjugate salt
• weak acid and its conjugate base
• strong acid and its conjugate base

Which solution A and B of equal volume and concentration mixed together to form a buffer?

• Nitric acid and potassium hydroxide
• Nitric acid and potassium nitrate
• Propanoic acid and potassium hydroxide
• Propanoic acid and potassium propanoate

Which of the following could be added to a solution of excess ethanoic acid to prepare a buffer?

• NaOH

• HCI

• NaCI

• More ethanoic acid

Which of the following statements is TRUE about buffer solution?

• pH of buffer solution will never change despite addition of small amount of base or acid

• An acidic buffer can be made by mixing weak acid and salt of its conjugate base or by mixing excess of weak acid with a strong base.

• the closer the ratio of concentration weak acid/base to the concentration of salt of its conjugate base/acid, the less effective the buffer to resist pH change

What statements CAN BE TRUE about acidic buffer?

(you may choose more than one answer)

• It's made of a mixture of weak acid and salt of its conjugate base

• Concentration of H⁺ ions in acidic buffer is greater than concentration of OH^- ions which is present in the solution

• Dilution of buffer by adding small amount of water doesn't change the pH of buffer solution

• acidic buffer usually works effectively at pH range of above 7

a buffer solution is made of mixture of aqueous methanoic acid, HCOOH, with aqueous sodium methanoate, NaHCOO.

the equilibrium reaction takes place in buffer solution is :

HCOOH ↔ HCOO^- + H⁺

small amount of NaOH is then added to that buffer solution.

What reaction take places at the buffer solution to resist change of pH caused by addition of base?

• HCOOH + H⁺ → HCOOH₂

• HCOO^- + H⁺ → HCOOH

• HCOOH + OH^- → HCOO^- + H₂O

• HCOO^- + OH^- → COO^2- + H₂O

a buffer solution is made of mixture of aqueous ethanoic acid, CH₃COOH, with aqueous potassium ethanoate, KCH₃COO.

the equilibrium reaction takes place in buffer solution is :

CH₃COOH ↔ CH₃COO^- + H⁺

small amount of HCl is then added to that buffer solution.

What reaction take places at the buffer solution to resist change of pH caused by addition of acid?

• CH₃COO^- + H⁺ → CH₃COOH

• CH₃COO^- + OH^- → CH₂COO^2- + H₂O

• CH₃COOH + H⁺ → CH₃COOH₂

• CH₃COOH + OH^- → CH₃COO^- + H₂O

Equilibrium reaction of carbon dioxide (CO₂) and hydrogencarbonate (HCO₃^-) ions in blood is one of the important buffer system that contribute to stabilise pH of the blood

CO₂(aq) + H₂O(l) ↔ H⁺(aq) + HCO₃^-

Which one take place on the buffer system when blood are slightly acidic than it would be normally ?

• equilibrium of the buffer system shifts to the right

• more hydrogencarbonate (HCO₃^-) ions are consumed in reaction with excess acid to produce more dissolved CO₂

• more dissolved CO₂ are consumed from the blood to remove excess acid and produce more hydrogencarbonate (HCO₃^-) ions

• No shift of the equilibrium take place on the buffer system

Tags

NGSS.HS-PS1-4