Nirave Gondhia – Titration Coursework
Skill Area P
Aim:
To find the percentage composition of citric acid in lemon squash. I will do this by finding out the molar concentration of the citric acid in 1L of water.
Prediction:
I predict that there will be around 2% of citric acid in lemon squash.
I say this, because otherwise the lemon squash would be too acidic, and would not be drinkable.
Background Knowledge:
Introduction- The goal of this experiment is to determine which fruit , lemon, lime, grapefruit, or orange has the most citric acid (C6H8O7) in it. This will be determined by collecting the juice of each fruit and then titrating the juice with NaOH. By determining the amount of NaOH that is needed to reach the endpoint in the tiration, it will be possible to determine which fruit has the most citric acid in it. This acid-base titration will work because the NaOH that will be added to the juice will react with the citric acid in the fruit juice and once enough NaOH has been added, the moles of NaOH will equal the moles of citric acid. The reaction that will govern the process is;
C6H8O7 + NaOH -> C6H7O7 + H20 + Na+.
This reaction will create a change in pH that can be detected using an indicator such as phenolphthalein. The juice that requires the most NaOH to reach an endpoint, which will occur when the solution turns pink, contains the most citric acid.
Materials & Methods- In order to complete the acid-base titration that will be used in this experiment, several pieces of equipment need to be obtained. The equipment that will be used during this experiment includes a 50mL buret, 100mL volumetric flask, 10mL pipet, ring stand, phenolphthalein indicator, 0.1028M NaOH, a knife, 2 oranges, 2 lemons, 4 limes, 1 grapefruit, and other common lab equipment. All chemicals, samples, and equipment described above were provided by the Chemistry Department Preparation Room except for the oranges, lemons, limes, and grapefruit, which were provided by the researcher.