Chemistry 1121

MEASUREMENT OF pH: pH TITRATION OF STRONG AND WEAK ACIDS AND pH MEASURMENT OF BUFFERS

Name:

Lab partner(s) name: N/A

Instructor’s name: Raji Balagopal

Course name: Chemistry 1123 Date: April 1, 2021 Due Date of the lab: April 14, 2021 Location: VCC

Objective: • Here the objectives of the experiments are provided.

• Remember to include all important chemical equations. Methods:

Wallace, J.G et al. (2016) Chemistry 1121 Laboratory Manual, Revised Edition. Vancouver BC: VCC. p (47-55)

Introduction:

The Introduction is presented in paragraph form. The intention of the introduction is to “introduce” the topic of the paper. For the

formal report it should provide a brief overview of the literature (background) such that the reader can evaluate and understand the

rational for conducting the experiments. It should not be considered as an exhaustive review of the literature.

Within the body of the introduction and for the informal lab report, the experimenter should define the purpose of these experiments.

The purpose should clearly define the problem. Note: if the problem is not clearly defined the reader will not understand why this

work was carried out.

To get a better idea of what is required, it is recommended that you review some recently published chemistry articles. Be sure to

consider the following:

• Why was the study necessary and how did you resolve it?

• What techniques/protocols were used?

Following are few points to consider when writing this section.

Background

• Definitions may be included in this section as long as they do not define something that the reader is already familiar with.

• Do not make references to anything that comes as a result of doing the experiment.

Write about Lab Manual pg 47:

i) pH titration

ii) Titration curves

iii) equivalence point

iv) half equivalence point

v) pKa and Ka (Write in paragraph form)

Results:

•Table 1- pH and volume data for titration of HCl and NaOH

•Table 2- pH and volume data for titration of CH3COOH and NaOH

(Please make a new copy of the table and attach the rough one)

•Graph -1 Titration of HCl and NaOH to determine the molarity of NaOH solution

•Graph-2 Titration of acetic acid and NaOH to determine molarity and pKa of acetic acid

?In the graph draw and show how the equivalence point is determined.

?Circle the equivalence point in graph -1

?Circle the equivalence point, half equivalence point and pH at the half equivalence point in graph 2 Calculations:

· From the data obtained from graph 1-determine the molarity of NaOH solution

· From the data obtained from graph 2- determine the molarity of acetic acid, pKa and Ka of acetic acid-Follow steps given in prelab

· From the appendix in Textbook find Ka of acetic acid (Acetic CH3COOH 1.8 x 10- 5)

· Calculate % accuracy % accuracy =(| Experimental value-Theoretical value|)/(Theoretical value) x100

(Note: for the value to be accurate, % accuracy value should be less than 1%)

· Compare the theoretical Ka and the experimental Ka – ie is the value accurate?

· Reasons for difference- if the Ka value is not accurate

Conclusion

Reference

References