Extended Essays 2021

Procedure:

Appendix #4-7 for risk assessment & extended methodology

Calibration Curve:

1. All chemicals and equipment were organised ( Appendix #8 ).

2. The Ferric chloride calibration curve was graphed by preparing the 0.01% Ferric chloride

solution and five dilutions of pure methyl salicylate (10, 20, 30, 40, 50%) with pure

ethanol as the solvent ( Appendix #9 ).

3. Once volumes of the ferric chloride solution, diluted methyl salicylate and additional

ethanol were combined, the solution was transferred into the glass cuvette and measured

of the light absorbance in the UV spectrophotometer at 515nm

4. The absorbance values of the diluted methyl salicylate with ferric chloride were recorded

for three trials and averaged to graph the calibration curve seen in Figure #4 .

Methyl salicylate synthesis 5. The reaction mixture - Salicylic acid (28g), methanol (80 3 ), and conc. Sulfuric acid (8 3 ) were placed into the 250 3 round-bottom flask and set under reflux for 1 hour

at 100V.

6. After reflux, the solution was refined through the evaporation of methanol on the hot plate

for 30 minutes. 7. Once formed the aqueous layer was separated from the oil by adding 250 3 of deionized water into the separatory funnel with the solution. 8. The oil was transferred into the 50 3 volumetric flask and was ‘dried’ of the excess

water with 5g magnesium sulphate. The flask was then shaken and left to stand for at least

half an hour.

9. The solution was then filtered through the funnel and filter paper.

10. Once filtered, the mass of the solution was weighed on the electronic balance 11. 2 3 of the synthesized solution was then combined with 1 3 of the ferric chloride solution and 7 3 of ethanol. This solution was transferred into another glass cuvette and

measured of its light absorbance value in the UV spectrophotometer.

12. Steps 5-11 were completed for the rest of the reflux durations (2, 3, 4 & 5 hours), three

trials each. The average absorbance for each of the solutions were then used with the

equation of the standard calibration curve to determine the percentage concentration of

synthesized methyl salicylate.

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