Problem: Based on the Henderson-Hassalbach equation how many mmols of Tris-HCl are there in a 100 mL of a 100 mM Tris-HCl buffer solution at pH 8.1? Note that the 100 mM refers to the sum of Tris and Tris-HCl concentrations. Answer in mmols.You now generate a NEW buffer solution by adding 0.1 mL of 10 M HCl to the solution in the previous question, how many mols of Tris-HCl would you now have in the NEW buffer solution? Answer in mmols.What is the ratio of Tris-HCl to Tris (mmols) in the NEW buffer solution?Based on the Henderson-Hassalbach equation, what is the pH of the NEW buffer solution?

FREE Expert Solution

We’re being asked to calculate the mmols of Tris-HCl are there in a 100 mL of a 100 mM Tris-HCl buffer solution at pH 8.1.


A solution that contains a weak acid and its conjugate base is a buffer solution. The pH of a buffer solution can be determined using the Henderson-Hasselbalch equation.

pH=pKa+log (conjugate baseweak acid)


Given solution:

    Tris-HCl    ⇌   Tris
(weak acid)    (conjugate base)


We can use the Henderson-Hasselbalch Equation to solve for the ratio of the weak acid and the conjugate base.

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Problem Details

Based on the Henderson-Hassalbach equation how many mmols of Tris-HCl are there in a 100 mL of a 100 mM Tris-HCl buffer solution at pH 8.1? Note that the 100 mM refers to the sum of Tris and Tris-HCl concentrations. Answer in mmols.

You now generate a NEW buffer solution by adding 0.1 mL of 10 M HCl to the solution in the previous question, how many mols of Tris-HCl would you now have in the NEW buffer solution? Answer in mmols.

What is the ratio of Tris-HCl to Tris (mmols) in the NEW buffer solution?
Based on the Henderson-Hassalbach equation, what is the pH of the NEW buffer solution?

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