- Purpose
The purpose behind conducting this experiment is to separate or extract Caffeine, which is an alkaloid and a weak organic base from the de-carbonated cola drink.
- Procedure
- A 125mL separatory funnel supported by an iron ring is taken and positioned on an iron stand. 60mL of de-carbonated cola drink is then transferred into it followed by the addition of 5.0mL Methylene Chloride (CH2Cl2) and insert the stopper.
- The pressure built inside the flask must be released by inverting it and opening up the stopcock instantly. The stockcock must be closed again while the contents of the flask are mixed by slowly inverting it. The process of pressure-release has to be repeated at least a couple of times.
- Next, the separatory funnel has to be placed on the stand and left undisturbed after removing the stopcock. During this time the top aqueous layer begins to separate from the bottom layer of methylene-caffeine. If any emulsion formation is noticed it must be stirred gently using a glass rod.
- At this point, the bottom layer of methylene chloride has to be drained into an Erlenmeyer flask. 5mL Methylene chloride is again added to the aqueous layer left in the separatory funnel twice and the previous steps are repeated. The methylene caffeine extracts obtained can be combined in one flask.
- Thereafter, anhydrous Na2SO4 is added to the methylene caffeine extract and swirled.
- This methylene caffeine extract is then poured into a 150mL beaker containing two to three boiling chips. Then about 2mL of methylene chloride is added to Na2SO4 and rinsed. It is then decanted into the 150mL beaker.
- The beaker is heated on low flame so as to evaporate methylene chlorine present in it. Crude caffeine is the solvent that remains in the beaker after the evaporation process gets completed. The weight of this caffeine that has been extracted and its melting point needs to be measured and recorded.
- Data Analysis
Melting point of the extracted caffeine=217°-232°
Mass of crude caffeine=mass of 150mL beaker with boiling stones and crude caffeine-mass of 150mL beaker with boiling stones
∴Mass of crude caffeine=75.9gm-75.8gm=0.1gm
- Error Analysis
The mass of caffeine in both the containers is found to be the same and hence there is no error. In other words, the error rate is zero.
- Interpretation
In this experiment, crude caffeine can be extracted from the cola drink with adequate accuracy and precision as proved by the results.
- Conclusion
The separation of caffeine from the de-carbonated cola drink can be carried out successfully in laboratory by following a set of steps and procedures with negligible or no error rate.
Solutions
- Methylene chloride is a non-polar organic solvent with a low boiling point and unlike water it has a structure similar to that of caffeine. Therefore, caffeine dissolves well in methylene chloride. Hence, methylene chloride, CH2Cl2 and not just plain water is used for the extraction of caffeine.
- Liquid-liquid extraction refers to the process of separating the different compounds present in a solution based on the difference in their solubilities.
- The chemical formula of caffeine is C8H10N4O2. Its structural formula is shown below.
Structural formula of Caffeine (chem..purdue.edu)
- There are several products that contain caffeine content such as the nergy drinks, coffee, fizzy drinks, tea and chocolate.
Work Cited
“Structural Formula,” chem.purdue.edu. N.p. n.d. Web. 12 Apr. 2013.
