Purpose: The purpose of this experiment was to learn and use the techniques of titration which would then determine the amount of acid in an unknown.
Introduction: .
One of the most common reactions in chemistry is the reaction of an acid with a base. This reaction is called neutralization. In this process an aqueous solution is the combination of hydronium ions with hydroxide ions to form water. The process of determining the concentration of a solution is called standardization and is achieved by the procedure of titration. A specific volume of a solution reacts with a standard solution of another substance where the concentration is known. The concentration of the unknown solution can then be calculated. In this experiment, this reaction will be used to determine the concentration of a sodium hydroxide solution. An indicator solution (phenolphthalein in this experiment) is used to show when the amount of acid equals the amount of base in the solution. It then changes color when this happens. This color change is called the "end point" of the titration. Phenolphthalein changes from colorless to pink at a pH of 9. The pH scale goes from 1 to 14. The pH of a substance is the negative logarithm of the concentration of hydrogen ions in a solution. This means that as the pH increases, the amount of hydrogen ions is decreasing and, therefore, the substance is less acidic. Since this is a logarithmic scale, each time the pH increases by one, it represents a ten-time decrease in the amount of hydrogen ions. In this experiment, sodium hydroxide was titrated against potassium hydrogen phthalate of known weight and KHP. .
Procedure:.
In this experiment there was a change in the procedure. In the standardization of NaOH, thewater was not boiled. This was on page 68 part A. The experiment was started by taking three Erlenmyer flasks and .4 to .6 grams of KHP was exactly weighed and added to the flasks.
