Ch. 15 Buffer Solution

The following solution mixture which is/are buffer . . .(you can select more than one)

• H₂PO₄^-1 and HPO₄^2-

• NH₃ and (NH₄)₂SO₄

• HCOOH and Ba(HCOO)₂

• H₃PO₄ and NaH₂PO₄

• NaOH and Ba(HCOO)₂

Which of the following mixtures of solutions that can form a buffer solution are . . .

• 50 mL CH₃COOH 0.2 M and 50 mL NaOH 0.1 M

• 50 mL CH₃COOH 0.2 M and 0 mL NaOH 0.2 M

• 50 mL HCl 0.2 M and 100 mL NH₄OH 0.1 M

• 50 mL HCl 0.1 M and 50 mL NH₄OH 0.2 M

• 50 mL HCl 0.2 M and 100 mL NaOH 0.1 M

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 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 have a pH greater than the pKa

What statement is true about basic buffer?

• basic buffer will have a pH greater than the pKa

• 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