What are the concentrations of acetic acid (pka = 4.76) and acetate in a buffer solution of 0.10 m at ph 4.9?

Solution:

We have to use the Henderson-Hasselbalch equation: for this calculation

Henderson–Hasselbalch equation describes the derivation of pH as a measure of acidity by using pKa, the negative log of the acid dissociation constant in biological and chemical systems. The equation is also useful for estimating the pH of a buffer solution and finding the equilibrium pH in acid-base reaction.  

The equation is given by:

Here, [HA] is the molar concentration of the un dissociated weak acid, [A⁻] is the molar concentration (molarity, M) of this acid's conjugate base and pKa is −log10 Ka where Ka is the acid dissociation constant, that is:

         pH = pKa + log([A^-]/[HA])  

We look up the pKa for acetic acid:  

pKa = 4.76  

Let x = molarity of AcO^- and y = molarity of AcOH: Then we have the following two equations in two unknowns:  

(1) x + y = 0.10 M  

and  

(2) 4.9 = 4.76 + log(x/y)  

Further calcite the value of x and y by algebraic method and get the answer.

Solution:

We have to use the Henderson-Hasselbalch equation: for this calculation

Henderson–Hasselbalch equation describes the derivation of pH as a measure of acidity by using pKa, the negative log of the acid dissociation constant in biological and chemical systems. The equation is also useful for estimating the pH of a buffer solution and finding the equilibrium pH in acid-base reaction.  

The equation is given by:

Here, [HA] is the molar concentration of the un dissociated weak acid, [A⁻] is the molar concentration (molarity, M) of this acid's conjugate base and pKa is −log10 Ka where Ka is the acid dissociation constant, that is:

         pH = pKa + log([A^-]/[HA])  

We look up the pKa for acetic acid:  

pKa = 4.76  

Let x = molarity of AcO^- and y = molarity of AcOH: Then we have the following two equations in two unknowns:  

(1) x + y = 0.10 M  

and  

(2) 4.9 = 4.76 + log(x/y)  

Further calcite the value of x and y by algebraic method and get the answer.

explanation: it gains negative electrons, therefore becoming negatively charged. as charge cannot be created, nor destroyed, only transferred, this leaves the wool positive. now that they have opposite charges, the two items attract.

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