Explore BrainMass
Share

# Acids, Bases and Indicators

This content was COPIED from BrainMass.com - View the original, and get the already-completed solution here!

4) Aniline, a weak base, reacts with water according to the reaction represented above.

a) Write the equilibrium constant expression, Kb, for the reaction represented above.
b) A sample of aniline is dissolved in water to produce 25.0mL of a 0.10M solution. The pH of the solution is 8.82. Calculate the equilibrium constsant, Kb, for this reaction.
*Note I have already figured out A and B to this problem...I just wanted to give it to you because the others build off of it. I do not understand how to calculate the pH, especially at the equivalence pt.
c)The solution prepared in part (b) is titrated with 0.10 m HCl. Calculate the pH of the solution when 5.0 mL of the acid has been added.
d) Calcuate the pH at the equivalence point in the titration in part (c).
e) The pKa values for the several indicator are given below. Which of the indicators listed is most suitable for this titration? Justify your answer.
Indicator pKa
Erythrosine 3
Litmus 7
Thymolphthalein 10