Problem 13
What is the relation between the \(\mathrm{p} K_{\mathrm{a}}\) of an acid and the strength of the acid? \( 6\)
Problem 14
The \(\mathrm{p} K_{\mathrm{a}}\) of acetic acid is 4.76 and the \(\mathrm{p} K_{\mathrm{a}}\) of trichloroacetic acid, which is used to remove warts, is 0.7. Calculate the dissociation constant of each acid. Which is the stronger acid? \(6\)
Problem 16
For an acid HA, the concentrations of HA and \(\mathrm{A}^{-}\) are 0.075 and \(0.025,\) respectively, at \(\mathrm{pH} 6.0 .\) What is the \(\mathrm{p} K_{\mathrm{a}}\) value for \(\mathrm{HA} ? 6\)
Problem 17
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 \(0.001 \mathrm{M}\) solution of a dye with a \(\mathrm{p} K_{\mathrm{a}}\) of \(7.2 .\) From the color, the concentration of the protonated form is found to be \(0.0002 \mathrm{M} .\) Assume that the remainder of the dye is in the deprotonated form. What is the \(\mathrm{pH}\) of the solution? \( {6}\)
Problem 18
An acid with a \(\mathrm{p} K_{\mathrm{a}}\) of 8.0 is present in a solution with a pH of 6.0. What is the ratio of the protonated to the deprotonated form of the acid?\( {6}\)
Problem 20
. Calculate the concentration of acetic acid and acetate ion in a \(0.2 \mathrm{M}\) acetate buffer at \(\mathrm{pH}\) 5. The \(\mathrm{p} K_{\mathrm{a}}\) of acetic acid is \(4.76 . \%\) 6
Problem 21
You are working in a high-powered clinical biochemistry lab. The chief scientist rushes in and announces, "I need \(500 \mathrm{ml}\) of \(0.2 \mathrm{M}\) acetate, \(\mathrm{pH}\) 5.0. STAT! Who is the best and brightest in this room?" All eyes turn toward you. You have solid anhydrous sodium acetate \(\left(\mathrm{MW}=82 \mathrm{g} \mathrm{mol}^{-1}\right)\) and a solution of \(1 \mathrm{M}\) acetic acid. Describe how you would make the buffer. \(\quad 6\)
Problem 22
Following a bout of intense exercise, the \(\mathrm{pH}\) of the exerciser's blood was found to be \(7.1 .\) If the \(\mathrm{HCO}_{3}^{-}\) concentration is \(8 \mathrm{mM},\) and the \(\mathrm{p} K_{\mathrm{a}}\) for \(\mathrm{HCO}_{3}^{-}\) is \(6.1,\) what is the concentration of \(\mathrm{CO}_{2}\) in the blood? \({6}\)
