Acid Base Titration

The purpose of this lab was to perform titration curves so that the percent of active ingredients in two commercial cleansers, Lysol and Liquid Plummer, could be found. Another purpose of this lab was to find the diluted concentration of NaOH. Titration is a common method of determining the amount of concentration of an unknown substance. It is an experiment in which a measured amount of one reactant is placed in a beaker and the second reactant is added slowly from a buret.

In this experiment, instead of using the normal method of titration, which involves slowly adding the titrant drop by drop into the buret, the flow rate method was used. The flow rate is quicker, but is also quite accurate. Flow rate is calculated by determining the volume of titrant used divided by the amount of time required. [F=V(ml)/t(s)]

If a solution of an acid is titrated with a solution of a base (or visa versa), the equivalence point can be found. The equivalence point is the point at which chemically equivalent quantities of acid and base have been mixed. The equivalence point can be found two ways: by the means of an indicator, which changes color at the equivalence point, or by the steepest region of the titration curve. In this experiment, the second way was used.

A titration curve is a plot of the pH of a solution against the volume of titrant. The pH can be measured directly with a pH meter while titrant is added through a buret. In this experiment, the titrants were a diluted solution of NaOH and HCl.

The molarity of the diluted NaOH solution was found by a simple M1V2=M2V2 calculation, because the molarity was listed on the box in the lab. The percent of the active ingredients in the cleansers was found by the titration curves. Using the titration curves, the equivalence point, pH, and volume of titrant added could be determined, which allowed for the calculation of percent weight.

Lysol is an acidic cleanser, containing hydrochloric acid as an active ingredient. Liquid-Plumr is a basic cleanser containing sodium hypochlorite.

There are many practical applications of titrations. For example, one could use titration to determine which orange juice has the most vitamin C. In this example, titration is used to determine the different concentrations of vitamin C in different orange juices.

Methods:

Standard safety precautions were taken and wastes were disposed properly.

First, using MicroLAB, the pH electrode was calibrated with pH 4.0, 7.0, and 10.0 buffer, placing pH on the y-axis. Keyboard was added as a sensor and was labeled volume, placing it on the x-axis.

Next, a plastic pop bottle was obtained and rinsed thoroughly with deionized water. Using a 50 mL graduated cylinder, 15 mL of 2.5 M NaOH solution was poured into the bottle and then 400 mL of deionized water was added