Soxhlet Extraction of Coffee Coffee components are extracted into water through specially designed glassware.
Purpose This simple experiment shows how a natural products are often extracted to concentrate soluble materials. A soxhlet extractor is specially designed for such extractions.
Demonstration This experiment shows the glassware setup required for a soxhlet extraction. Coffee is placed in the extraction “thimble” The experiment shows how vaporization and condensation occur throughout the apparatus.
Concepts Extraction Changes of State Solubility
Extraction Extractions are used when we want to separate substances. One way this can be done is by using a solvent in which a desired substance dissolves in and the undesired substance does not dissolve in. Coffee flavor from coffee grounds is a great example, as we leave behind the coffee grounds and obtain a great flavored morning beverage.
Changes of State Evaporation -the phenomenon in which liquid molecules have enough energy to convert to the gaseous state without boiling -evaporation can occur at nearly any temperature: at any time some of the molecules in a liquid will have enough energy to escape into the air Condensation -the phenomenon in which gas molecules lose energy required to be a gas and collect on a cool surface as a liquid -example, on a hot, humid summer day water condenses on the outside of a glass of ice water When molecules have lower energy their intermolecular attractions take hold
Solubility Solubility is a function of how well a substance dissolves in a solvent. Coffee grounds are insoluble in water (nothing dissolves) However, the flavorings in the coffee grounds are soluble in water (large amounts dissolve)—they are said to be the solute in the solution In this demonstration, the soluble flavorings are what we want in our water. Coffee is a solution: solutions include a solute (substance being dissolved) and a solvent (substance doing the dissolving)
Conclusions Using a soxhlet extractor is a way to separate soluble material from insoluble material A soxhlet extractor repeatedly extracts with fresh solvent until it is stopped. Thus, it is possible to extract all of the soluble material, if given enough time. This would make for really strong coffee in this demonstration!
Comments A soxhlet extraction is commonly used to extract compounds from plants to discover active compounds such as natural pharmaceuticals Compounds extracted from plants or animal material are commonly called natural products Some natural products are very useful chemical species for the production of drugs and ointments