GEORGIA MILITARY COLLEGE

NATURAL SCIENCE DEPARTMENT

ONLINE CAMPUS

LABORATORY 4 ACID-BASE TITRATIONS

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STUDENT NUMBER

CLASS

PROFESSORS TITLE AND NAME

Introduction

Acid-base titration is a process used to determine the concentration of an acid (or base) whose concentration is unknown by neutralizing it with a base (or acid) of known concentration (Spencer, 2024). The solution whose molarity is known is referred to as the titrant, while that of unknown molarity is the titrand (Spencer, 2024). In the general titration process, the titrand is placed in a flask along with a small quantity of indicator (Spencer, 2024). The titrant is added to a burette and added gradually to the mixture containing the titrand and indicator until the mixture changes color (Spencer, 2024). The volume of the titrant when the color change occurs is recorded and used to calculate the concentration of the titrand using the relationship below:

n acid = n base

But n = MV; and hence

MacidVacid = MbaseVbase

So

Mbase = (MV) acid/Vbase

The above equation (equation 1) gives the formula for obtaining the concentration (M) of a base whose concentration is unknown. Vacid is the volume of the acid (titrant) used in the process of titration, Macid is the concentration of the titrant (acid), and Vbase is the initial volume of the titrand (base). From the titration data, one could generate an acid-base titration curve, which is a plot of the titrands pH against the added titrants volume at different points of the titration process. The slope of the titration curve will be negative or positive, depending on whether the titrant is an acid (curve will have a positive slope) or a base (curve has a negative slope).

This laboratory sought to realize three core objectives:

i) To enhance understanding of the titration technique

ii) To enhance understanding of neutralizing reactions

iii) To increase ability to develop the titration curve and calculate the concentration of a titrand from titration data.

The laboratory uses phenolphthalein as the indicator. Phenolphthalein changes color...

This text hypothesizes that in an alkaline environment, phenolphthalein is pink, and will change to colorless as more acid is added (Spencer, 2024).

Materials and Methods

Preparing the Lab

i) Click on the link labeled Virtual Lab on the course home page to activate the lab environment.

ii) Wait for the lab environment to load, then choose File, and subsequently, Load an Assignment.

iii) In the category labeled Acids and Bases, choose the lab 4 assignment titled Prelab exercises:...

…caution was taken to ensure accurate results, the accuracy of the procedure can be improved further by conducting the experiment multiple times to check for consistency in the collected data.

From equation 1, the molarity of the titrand (NaOH) can be calculated as follows:

Mbase = (MV) acid/Vbase

At the equivalence point; Macid = 0.1M, Vacid = 2mL, and Vbase = 5mL; hence

Mbase = (0.1 x 2)/5

Mbase = 0.04M

Conclusion

This experiment entailed conducting a titration between NaOH (titrand) and HCL (titrant), and using the collected data to calculate the molarity of the titrand. The experiment sought to enhance understanding of titration techniques, neutralizing reactions, and to guide in developing a titration curve from titration data. 5mL NaOH mixed with 0.2mL phenolphthalein was titrated against 0.1M HCL that was added gradually in quantities of 2mL until the solutions volume was 40mL, and 1mL thereafter. The titrand solution was pink in color, and changed to colorless when the equivalent point was attained. No further color change was observed with addition of more HCL since phenolphthalein is colorless in acidic environments. The titration curve developed from the collected data showed the equivalence point was attained when the pH of the solution was 7. While the necessary steps were taken to ensure accuracy, the accuracy of the procedures…