Buffer solution (qualitative)

Which of the following statements ARE TRUE about buffer solution?

(you may choose more than one answer)

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

• Buffer can be made by mixing weak acid and salt of its conjugate base or by mixing weak base with salt of its conjugate acid

• Buffer has acid and base components that can work specifically to resist pH change

• 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

What statements CAN BE TRUE about basic buffer?

(you may choose more than one answer)

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

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

• adding small amount of strong acid to the solution of basic buffer can significantly alter the pH of the buffer solution

• diluting solution of basic buffer cause pH of that solution to change drastically

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

Which of the following mixture that may produce buffer solution to work at pH of below 7?

(you may choose more than one answer)

• NaOH (in excess) + HCN

• KOH + NaCH₃COO

• HCOOH + NaHCOO

• KOH + HF (in excess)

• HCOOH + CH₃COOH

Which of the following mixture that may produce buffer solution to work at pH of above 7?

(you may choose more than one answer)

• HCl + NH₃ (in excess)

• Mg(OH)₂ + HF (in excess)

• NaCN + HCN

• NH₃ + NH₄NO₃

• H₂SO₄ (in excess) + NH₃

Which of the following mixture that won't produce a buffer solution?

(you may choose more than one answer)

• LiOH + LiF

• HCl (in excess) + KOH

• HNO₃ (in excess) + NH₃

• NaOCl + NaOH

• CH₃COOH + Mg(CH₃COO)₂

Which of the following composition or mixture will, in general, form a solution of acidic buffer ?

(you may choose more than one answer)

• strong acid + weak base (in excess)

• strong base + weak acid (in excess)

• weak acid + salt of its conjugate base

• weak base + salt of its conjugate acid

• strong acid (in excess) + strong base

Which of the following composition or mixture will, in general, form a solution of basic buffer ?

(you may choose more than one answer)

• strong acid + weak base (in excess)

• strong base + weak acid (in excess)

• weak acid + salt of its conjugate base

• weak base + salt of its conjugate acid

• strong acid + strong base (in excess)