The benzoic acid is used in industry as a food preservative under the E220 code. It is a white silky-looking solid. To determine the concentration of this additive in a soda, one can realize a pH titration: a strong base (the titrant) is progressively added to a sample of the soda (the analyte), and pH is then read.
The generated curve is typical, and has an area where pH brutally increases: it is the pH-jump.
To find the concentration of preservative in the soda, the volume of added titrant at the equivalence point (ie at the middle of the pH-jump) must be read. There are two main approaches to do so:
- the derivative method, which consists in calculating the derivative of the curve; the equivalence point matches with the maximum of this derivative
- the parallel tangents method, which consists in drawing two parallel tangents from one part and another of the pH-jump, then to draw a third straight line equidistant from the two first. The equivalence point is at the intersection between this last line and the curve.
See the subject for further details !
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Grade : B | Mark : 13.2
| Category | Percentage | Tests | Crash ? |
|---|---|---|---|
| Basic | 100% | 2/2 | x |
| Derivative | 100% | 3/3 | x |
| Edge cases | 0% | 0/3 | x |
| Interpolation | 33.3% | 1/3 | x |
| Rigor | 88.9% | 8/9 | x |
| End scores | 70% | 14/20 | No |
Made with Quentin TREHEUX (LuciferBahamut)
Beware of -42 Epitech students !!!