Titration of strong acid with weak base is a laboratory technique used to determine the concentration of an acid by reacting it with a known concentration of a base. This allows for the calculation of the acid's concentration and can also be used to determine the acid's dissociation constant.
In this titration, a burette is filled with a known concentration of a base and the acid is slowly added to it until the equivalence point is reached. The equivalence point is where the moles of acid and base are equal, and it is determined by using an indicator or a pH meter. The volume of acid used at the equivalence point is used to calculate the acid's concentration.
Using a strong acid and a weak base allows for a more precise determination of the acid's concentration. This is because the pH at the equivalence point will be closer to 7, making it easier to determine the endpoint using an indicator or pH meter.
The most commonly used indicators in this titration are phenolphthalein and methyl orange. Phenolphthalein changes color at a pH of around 8.3, making it ideal for titrations involving weak bases. Methyl orange changes color at a pH of around 4.4, making it useful for titrations involving strong acids.
Some sources of error in this titration include impurities in the chemicals used, inaccurate measurements of volume, and incomplete neutralization due to the presence of excess acid or base. It is important to perform multiple trials and calculate an average to minimize these errors.