Extraction of Caffeine

Students will learn about caffeine which is a type of alkaloids. Caffeine is a stimulant found naturally in tea, coffee and kola nuts. Other examples of alkaloids include cocaine (a drug of abuse), strychnine (a poison), morphine (a pain killer), piperine (found in black pepper) and quinine (used to treat malaria and added to tonic). Clearly some alkaloids are beneficial and others extremely harmful.In this project, students will learn how to extract caffeine from different beverages.

In the experiment, caffeine is to be extracted from the tea that will be brewed. Techniques such as Buchner filtration, solvent extraction and distillation using a rotary evaporator will be utilised during the process

A useful rule of thumb for judging solubility is “like dissolves like”. Organic compounds tend to be soluble in organic solvents. Polar materials, such as salts tend to be more soluble in polar solvents, such as water.

Some organic compounds are exceptions and are more soluble in water than in organic solvents. This is because they have a large number of polar functional groups, such as hydroxyl groups, relative to the amount of hydrocarbon. Glucose is an example of this kind of molecule. 

In general, an organic compound and an inorganic salt can be easily separated using these solubility differences. If a mixture of 1,4-dimethoxybenzene and lithium chloride is dissolved in a mixture of diethyl ether and water, both will dissolve. The mixture will separate into two clear layers. One will be the “organic layer” and it will contain the 1,4- dimethoxybenzene. The other will be the aqueous layer, and it will contain the lithium chloride. If the organic layer is separated from the aqueous, dried to remove traces of water and then evaporated, pure 1,4-dimethoxybenzene will be obtained. 

Fastest Ball Challenge

The main objective of this challenge is to determine the angle of inclination, θ, for which the time of travel across the horizontal track will be least (See Figure 1). Students will have to make use of the concepts of conservation of energy, kinetic and potential energy to win this challenge. Students will also make use of a stopwatch and photogate sensors in their data acquisition.

The group needs to adjust the angle of inclination of horizontal track, such that the time travelled across the whole track is as minimal as possible. Photogate sensors and stopwatches are provided to acquire data.

Newton's laws are used for the solution of many standard problems, but often there are methods using energy which are more straightforward. For example, the solution for the impact velocity of a falling object is much easier by energy methods. The basic reason for the advantage of the energy approach is that just the beginning and ending energies need be considered; intermediate processes do not need to be examined in detail since conservation of energy guarantees that the final energy of the system is the same as the initial energy.

In order to help us in understanding “work”, we introduce the concept of vectors, and a useful tool, the scalar product, also known as the dot product.
A vector quantity is completely specified by a magnitude with appropriate units and has a direction. The convention for vectors in this manual is bold face, with an arrow on top of the quantity.

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