CHEM 110 Lecture Notes - Lecture 1: Buffer Solution, Conjugate Acid, Titration CurveExam


Department
Chemistry
Course Code
CHEM 110
Professor
Xu
Study Guide
Final

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Buffer Problem
1. Explain why an ‘effective’ acidic buffer, has a pH close to the value of the pKa of the acid.
2. What does a buffer with a pH significantly larger than the pKa tell one about the ratio of the acid to salt
(conjugate base) ratio?
3. What does a buffer with a pH significantly smaller than the pKa tell one about the ratio of the acid to salt
(conjugate base) ratio?
Lactic acid (C3H6O3) and hydrocyanic acid (HCN) have Ka’s of 1.38 x 10-4 and 6.17 x 10-10 respectively
a) Show how HCN dissociates in water and identify all of the acid/base conjugate pairs.
b) Which is the stronger acid? Explain.
c) What is the formula of the conjugate base of lactic acid?
A 20.0 mL 0.100 M solution of lactic acid is titrated with 0.100 M NaOH.
a) A buffer solution exists in the flask after 5.00 mL of NaOH have been added. Write equations to show the action
of each component of the buffer when acid or base is added from an external source.
b) Calculate the moles of lactic acid present in the flask before the titration
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