A biochemical buffer is being prepared to operate at body temperature ( )
CHEMISTRY · Multi-part · A Level · Chemistry · Acids and bases · Acids and bases
Problem
A biochemical buffer is being prepared to operate at body temperature (40∘C). The solution is found to contain 5.00×10−6molL−1 hydroxide ions at this temperature. At 40∘C, the ionic product of water is Kw=2.92×10−14.
(a) Calculate the pOH of the buffer solution at 40∘C, showing every step in your calculation and maintaining correct significant figures.
(b) Using the given value of Kw, determine the hydronium‐ion concentration and the pH of the solution at 40∘C. Clearly indicate how you incorporate temperature effects into your work.
(c) Compare the pH you obtained in part (b) to the pH of neutral water at 40∘C. Explain, with quantitative support, whether the buffer is acidic, neutral, or basic under physiological conditions.
(d) Suppose the target pH for the buffer is 7.40 at 40∘C. Calculate the factor by which the hydronium‐ion concentration must be adjusted (expressed as a ratio [H3O+]desired/[H3O+]current) to achieve the desired pH. Discuss briefly one practical method a chemist might use to implement this adjustment in the laboratory.