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Chemistry LibreTexts

Solutions that are Mixtures of Acids and Bases, Problem B

5.  Calculate the pH of a solution that is prepared by mixing 75 mL of 0.088 M aniline with 50 mL of 0.097 M nitrophenol (2-).

Since this is just another neutralization reaction, the groups can usually advance through the following steps with minimal prompting.

Which is the acid and which is the base?

What is the chemical equation representing this system at equilibrium?

What is Kn for this neutralization? Does it go to completion?

In this case, the value of Kn is small and most groups realize that they know how to do a set up a calculation for a reaction with a small K value.

What assumptions can we make? What is the value of x for this system?

What do we have in the solution when it has reached equilibrium?

Which conjugate pair should we use to calculate the pH? Does it matter?

It is useful to have every group or different groups calculate the pH using the two different sets of conjugate pairs to show that the pH is the same for each of the two.