You will use indicators to observe end points in neutralization reactions with titrations of strong acids and bases.
After completing this tutorial, you will be able to complete the following:
A neutralization reaction is the reaction of an acid and a base to produce a salt and water. Since antacids are basic salts, they act to neutralize excess stomach acid, which can help to alleviate acid indigestion.
A substance that changes color in either an acid or a base is called an indicator. Many dyes and natural substances can act as indicators, such as the juice of red cabbage. Red cabbage juice turns red with vinegar (acid) and blue-green with baking soda (base). There are a variety of indicators that can change colors within the pH spectra and the correct indicator should be used accordingly. Bromothymol blue is used in this experiment as it changes color near pH seven, which is the endpoint of a reaction between a strong acid and strong base.
A titration is a procedure in which a solution of known concentration (titrant) is used to determine the concentration of a second unknown solution (analyte). In the presence of an indicator, the titrant is added in small quantities to the analyte until the color change is observed. The color change indicates the endpoint of the reaction has occurred and the analyte is neutralized. The pH of the analyte can then be recorded with a pH meter.
|Approximate Time||20 Minutes|
|Pre-requisite Concepts||Learners should be familiar with identifying pH of substances, molarity and molality, properties of acids, properties of bases.|
|Type of Tutorial||Experiment|
|Key Vocabulary||acid, analyte, antacid|