4. a. Define: Buffer or remain the same) pH of a buffer solution change if we ad

Question

4. a. Define: Buffer or remain the same) pH of a buffer solution change if we add water? (Gincreases, decreases, c. Consider the table given below and write a balanced chemical equation for any reaction taking place between solute particles. Then write the formulas of the major particles present ( just as you would for a net-ionic equation) in each of the following solutions below. Decide on which of the solutions below woald showa buffer action. s it a buffer? (Yes or No) Partides present Na2CO3 NaHSO4 NaF Equal volumes of 0.10 M HCN and 005M NaOH Equation: Equal volumes of 0.05 M H2S and 0.10 M NaOH Equation NaHC204

Explanation / Answer

a)

A buffer is any type of substance that will resist pH change when H+ or OH- is added.

This is typically achieved with equilibrium equations. Both type of buffer will resist both type of additions.

When a weak acid and its conjugate base are added, they will form a buffer

The equations:

The Weak acid equilibrium:

HA(aq) <-> H+(aq) + A-(aq)

Weak acid = HA(aq)

Conjugate base = A-(aq)

Neutralization of H+ ions:

A-(aq) + H+(aq) <-> HA(aq); in this case, HA is formed, H+ is neutralized as well as A-, the conjugate

Neutralization of OH- ions:

HA(aq) + OH-(aq) <-> H2O(l) + A-(aq) ; in this case; A- is formed, OH- is neutralized as well as HA.

b)

pH of a buffer remains similar since ratio of

pH = pKa + log(a-/HA)

A-/HA = remains, since dilution will not affect the ratio

c)

i)

Na2CO3 + 2Na+ + CO3-2

this is not a bufer

ii)

NaHSO4 = Na+ + HSO4-

this is not a buffer

iii)

NaF --> Na+ + F-

this is not a buffer

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