Please answer all of the following: 1.) Using the Henderson-Hasselbalch equation

Question

Please answer all of the following:
1.) Using the Henderson-Hasselbalch equation, show that, for a weak acid, the pKa is the pH at which the concentration of the acid equals the concentration of the conjugate base.
2.) For an acid HA, the concentrations of HA and and A are 0.075 and 0.025, respectively, at pH 6.0 what is the pKa value for Ha?
3.) A dye that is an acid and that appears as different colors in its protonated and deprotonated forms can be used as a pH indicator. Suppose that you have a 0.001M solution of a dye with a pKa of 7.2. From the color, the concentration of the protonated form is found to be 0.0002M. Assume that the remainder of the dye is in the deprotonated form. What is the pH of the solution? Please answer all of the following:
1.) Using the Henderson-Hasselbalch equation, show that, for a weak acid, the pKa is the pH at which the concentration of the acid equals the concentration of the conjugate base.
2.) For an acid HA, the concentrations of HA and and A are 0.075 and 0.025, respectively, at pH 6.0 what is the pKa value for Ha?
3.) A dye that is an acid and that appears as different colors in its protonated and deprotonated forms can be used as a pH indicator. Suppose that you have a 0.001M solution of a dye with a pKa of 7.2. From the color, the concentration of the protonated form is found to be 0.0002M. Assume that the remainder of the dye is in the deprotonated form. What is the pH of the solution?
1.) Using the Henderson-Hasselbalch equation, show that, for a weak acid, the pKa is the pH at which the concentration of the acid equals the concentration of the conjugate base.
2.) For an acid HA, the concentrations of HA and and A are 0.075 and 0.025, respectively, at pH 6.0 what is the pKa value for Ha?
3.) A dye that is an acid and that appears as different colors in its protonated and deprotonated forms can be used as a pH indicator. Suppose that you have a 0.001M solution of a dye with a pKa of 7.2. From the color, the concentration of the protonated form is found to be 0.0002M. Assume that the remainder of the dye is in the deprotonated form. What is the pH of the solution?

Explanation / Answer

Henderson- Hasselbalch equation can be written as

pH= PKa + log [Concentration of conjugate base/ Concentration of conjugate acid]

Since concentration of conjugate base = concentration of conjuagate acid

pH= pKa

2. pH= PKa+ log[A-]/[HA]

6= PKa + log[0.025/0.075)

pKa= 6.4777

3. pKa =pH + log (concentration of protanated form/ concentration of unprotanated form)

7.2= pH+ log [ 0.0002/ 0.001-0.0002)

pH= 7.2+0.6=7.8

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