How do you find the equivalence point on a titration graph
To find the equivalence point on a titration graph, you need to identify the point at which the moles of the titrant (added from the burette) completely react with the moles of the analyte (present in the sample). The equivalence point represents the stoichiometrically equivalent amount of titrant required to react with the analyte.
There are a few methods you can use to find the equivalence point on a titration graph:
1. Phenolphthalein indicator: For acid-base titrations, phenolphthalein is commonly used as an indicator. It changes color at a pH around 8. At the equivalence point, when the moles of acid and base are equal, the solution should reach the pH at which phenolphthalein changes color. This color change can be seen as a sudden, sharp change in pH on the titration curve.
2. Endpoint determination: This method requires adding a solution, known as the indicator, that undergoes a color change near the equivalence point. Common indicators include phenolphthalein, bromothymol blue, or methyl orange. By observing the color change during the titration, you can determine the approximate point where the equivalence point occurs.
3. Calculation: In some cases, the equivalence point can be calculated mathematically based on the stoichiometry of the reaction. If you know the balanced chemical equation and the volumes and concentrations of the analyte and titrant used, you can perform stoichiometric calculations to find the exact point where the equivalence point occurs.
It is important to note that finding the equivalence point precisely is crucial for accurate results. However, experimental errors or uncertainties can make it challenging to determine the exact equivalence point on the graph.