The risks of titration
Titration is an analytical technique used in laboratories to determine the end point of a reaction. Two solutions are gradually mixed together until an equilibrium is reached. Standard chemistry glassware is used. The two solutions are typically an acid and a base.
The indicator is a chemical that produces a colour during the titration. Each aspect of a titration can cause injury, if the individual is not careful.
The burette, a graduated glass tube, is the essential tool required to perform a titration. The first burette was built by French chemist Francois Antoine Henri Descroizilles in 1791. Karl Friedrich Mohr took the concepts of volumetric analysis and redesigned the burette. In 1855, he established the methods for chemical analysis by titration.
Titration is used to determine the concentration of a known solution. Titration is also used to determine the exact reaction equation that takes place between two solutions of known concentration. By recording the volume of titrant added and the corresponding concentration or pH reading, one can establish a titration curve. This can identify whether an acid or base is weak or strong.
The required tools to perform a titration are a burette, a beaker or Erlenmeyer flask, ring stand with clamp, and a pH meter. Additional equipment like graduated cylinder and pipettes are required to prepare the solutions. All glassware poses a risk of cuts from broken glass. Check the burette stopcock for leaks to reduce risk of exposure to chemicals.
The titrant is poured into the burette to a desired volume. The analyte solution is in a beaker and placed under the burette. An indicator is added to the analyte solution. The burette is opened and allowed to pour into the beaker until a colour change is observed. Acids and bases used for the titrant and analyte can cause skin irritation or burns. Methyl orange and phenolphthalein are two indicators. They can stain the skin, cause irritation and can be toxic. Phenolphthalein is suspected as a carcinogen.
When handling acids, bases and chemical indicators, wear safety gloves. Neoprene, nitrile or natural rubber gloves provide adequate protection. The skin should be immediately washed with water for several minutes if exposed to any chemical. Wear safety glasses to protect eyes from splashing of chemicals during preparation and titration. During the titration, maintain a slow, steady stream of titrant. Avoid sudden stops and starts. This can weaken the stopcock and cause leaks. If the glassware breaks, use a dustpan and brush to clean up.