Advertisements
Advertisements
प्रश्न
Explain buffer action of sodium acetate-acetic acid buffer.
Advertisements
उत्तर
- Sodium acetate-acetic acid buffer is an example of an acidic buffer in which weak acid \[\ce{(CH3COOH)}\] and its salt with strong base are present.
Here sodium acetate \[\ce{(CH3COONa)}\] salt is a strong electrolyte, which dissociates completely in water.
Acetic acid is a weak electrolyte, hence does not dissociate completely.
Sodium acetate dissociates as given below:
\[\ce{CH3COONa_{(aq)} -> CH3COO{_{(aq)}^-} + Na{_{(aq)}^+}}\]
Due to the presence of the common ion \[\ce{(CH3COO^-)}\], dissociation of acetic acid is further suppressed. - Reserve acidity: When a small quantity of a strong base \[\ce{OH-}\] is added, the hydroxide ions react with the acid as follows:
\[\ce{CH3COOH_{(aq)} + OH{_{(aq)}^-} <=>CH3COO{_{(aq)}^-} + H2O_{(l)}}\]
This removal of added \[\ce{OH-}\] ions is called reversed acidity. - Reserve basicity: When a small quantity of strong acid is added to the solution, the added \[\ce{H+}\] ions will be consumed by the conjugate base \[\ce{CH3COO-}\] present in large concentration as given below:
\[\ce{CH3COO{_{(aq)}^-} + H{_{(aq)}^{+}} <=> CH3COOH_{(aq)}}\]
The removal of added H+ ions is called reversed basicity. - The acid or base added thus cannot change the \[\ce{[H+] or [OH-]}\] concentration, and the pH of the buffer remains unchanged. Dilution does not have any effect on pH of buffer. This is because the concentration ratio term in the following equation remains the same.
`"pH" = "pK"_"a" + log_10 "[Salt]"/"[acid]"`
`"pOH" = "pK"_"a" + log_10 "[Salt]"/"[base]"`
Hence, dilution does not change this ratio.
APPEARS IN
संबंधित प्रश्न
The ionization constant of benzoic acid is 6.46 × 10–5 and Ksp for silver benzoate is 2.5 × 10–13. How many times is silver benzoate more soluble in a buffer of pH 3.19 compared to its solubility in pure water?
When NH4 Cl and NH4OH are added to a solution containing both, Fe3+ and Ca2+ ions, which ion is precipitated first and why?
Cu is precipitated as CuS while Zn is not precipitated when H2S is passed through an acidic solution of Cu(NO3 )2 and Zn(NO3)2 respectively.
Choose the most correct answer:
Which of the Na following is a buffer solution?
Answer the following in one sentence :
Write one property of a buffer solution.
Answer the following in one sentence :
Classify the following buffers into different types :
NH4OH + NH4Cl
Answer the following in one sentence :
Classify the following buffers into different types :
Sodium benzoate + benzoic acid
Answer the following in one sentence :
Classify the following buffers into different types :
Cu(OH)2 + CuCl2
In biochemical system, pH of blood in our body is maintained due to the following buffer:
Name the buffer which is used to maintained pH of 8 to 10 for precipitation of cations III A group in qualitative analysis.
Write the formula to calculate pH of buffer solution.
Write one application of the following buffer:
Citrate buffer
Write one application of the following buffer:
`"HCO"_3^- + "H"_2"CO"_3`
____________ forms a basic buffer solution.
The hydrogen ion concentration of a buffer solution consisting of a weak acid and its salts is given by ____________.
On the basis of the equation \[\ce{pH}\] = – log \[\ce{[H+]}\], the \[\ce{pH}\] of 10–8 mol dm–3 solution of \[\ce{HCl}\] should be 8. However, it is observed to be less than 7.0. Explain the reason.
Assertion (A): A solution containing a mixture of acetic acid and sodium acetate maintains a constant value of \[\ce{pH}\] on addition of small amounts of acid or alkali.
Reason (R): A solution containing a mixture of acetic acid and sodium acetate acts as a buffer solution around \[\ce{pH}\] 4.75.
Assertion (A): An aqueous solution of ammonium acetate can act as a buffer.
Reason (R): Acetic acid is a weak acid and \[\ce{NH4OH}\] is a weak base.
Which of the following combinations will constitute a buffer solution?
Write any four applications of buffer solution.
Calculate pKa of HF if Ka= 7.2 x 10-4.
What is the pH of buffer solution prepared by mixing \[\text{0.2MNH4OHand0.4MNH4Cl}\] solution. \[(\mathrm{pK_{b}~of~NH_{4}OH=4.620})\]
A buffer solution is prepared by mixing 0.1 M ammonia solution and 0.25 M solution of NH4CI. What is the value of pKb to maintain its pOH at 6?
