ka lab report

Topics: PH, Acetic acid, Base Pages: 3 (692 words) Published: December 9, 2014
Determination of : Titration of a Weak Acid
Introduction:
We will be using the LoggerPro and LabPro in order to help us determine our data. The purpose of this experiment is to follow the changes of pH during the titration of an acid and a base in order to determine the of the weak acid, . is a constant for a given acid at a given temperature. In this experiment we determined the Ka using two different methods: 1) the measurement of the pH of a solution containing a known concentration of a weak acid, and 2) measurement of the pH at the half-neutralization point in the titration of a weak acid and a strong base. Theory and Concept:

When titrating a weak acid, HA, with a strong base the equilibrium between the weak acid and its ion is reestablished after every addition of base. The reaction in this titration is pushed towards the right after every addition of a base. At the beginning of a titration between a weak acid and a strong base, there is mostly HA in the solution with small amounts of H30+ and A- because only a small amount of base has been added therefore a small amount of ionization has occurred. As we added more base, more HA is ionized and more salt formation occurs meaning the concentration of HA will decrease while the concentration of A- will increase. The pH rises above the equivalence point because we are adding base to a solution with a relatively large volume. At the end of the titration the ratio of [A-]/[HA] goes from low to high. This means that all of the HA will be neutralized, causing the pH to change. Because of the rapid pH change around the equivalence point, the titrant has to be added in lesser and lesser amounts as we approach the equivalence point. Procedure:

CHM 113 Lab Manual, 2014, Determination of : Titration of a Weak Acid, pgs.89-96

Equations/Experimental Equipment and Apparatus:
LoggerPro, LabPro, pH probe, drop counter, 60 mL reagent reservoir, stir station

=p
Data and Observations:
Data:...
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