Extraction and chromatography as a methods of separating and identifying mixtures
what a substance and a mixture are;
what safety rules should be observed in the school's chemical workshop;
what the terms 'physical properties' and 'chemical properties' mean as well as how the properties of a substance can be tested;
according to what criteria mixtures are classified.
what the methods are for separating homogeneous and heterogeneous mixtures;
what laboratory techniques are used to separate mixtures;
to plan chosen methods for separating mixtures into components and to perform appropriate actions yourself;
to describe the possibilities of using the methods for separating of mixtures at home and in industry;
to use basic terms pertaining to mixtures and the way to separate them.
Extraction as a method for separating mixtures
ExtractionExtraction consists in washing desired components out of a solid or liquid mixture using a solvent, and the subsequent evaporationevaporation of the solvent. An example of the extraction process, in the solid – liquid arrangement, is the process of brewing tea or coffee.
Coffee brewing in an espresso machine is a type of extraction in which a solvent (hot water – liquid) is added to a solid (ground coffee beans) in order to dissolve one or more components.
The flavors contained in coffee diffuse from the beans into water (the extractant).
*The extraction time when preparing espresso should be approximately 25 seconds. During this time, the cup should be filled with approx. 25–30 ml of the infusion created after the passage of water through 7 g (1 portion) of ground coffee.
Hot water increases the dissolution rate of the components to be extracted. In the espresso machine, a filtrationfiltration stage takes place after the extraction stage.
Watch the movie. Pay attention to what and how was extracted from the arugula leaves.
Film dostępny na portalu epodreczniki.pl
Film pokazuje eksperyment „Ekstrakcja”. Extraction. Będziesz potrzebować: liście rukoli, kawałki ceramiki, etanol, palnik. Do etanolu dodajemy kilka kawałków ceramiki i liście rukoli. Całość podgrzewamy. Z liści rukoli puścił zielony sok.
ChromatographyChromatography is used to purify and identify substances. This method of analysis of mixtures is used in biological research, pharmaceuticals manufacturing and many other fields. The name chromatography comes from the Greek chromos meaning „colour”. The first application of this method allowed to separate natural vegetable dyes, e.g. green – chlorophyll, yellow – xanthophil, orange – carotene.
Watch the movie. Take note of how the chromatographic separation of photosynthetic pigments of arugula leaves takes place.
Film dostępny na portalu epodreczniki.pl
Film pokazuje eksperyment „Rozdział chromatograficzny barwników fotosyntetycznych liści rukoli”. Chromatographic separation of photosynthetic dyes of arugula leaves. Będziesz potrzebować: wata, skrobia, patyczek, pipeta Pasteura z obciętym fragmentem zbiorniczka, etanol, probówka. Do pipety wciskamy patyczkiem do końca małą kulkę z waty. Następnie wsypujemy skrobię, na koniec pipetę zatykamy kolejną kuleczką z waty. Na górę wkraplamy ekstrakt z liści rukoli i etanol. Kolor zielony ekstraktu rozchodzi się w dół pipety. Intensywniejszy jest na dole.
Observation of the crystallization process – separation of rock‑salt crystals from the solution.
Design your own experiment.
Now compare your experiment with the description below.
Crystallization from the solution is carried out by cooling the solution or evaporating the solvent.
water,
rock‑salt,
jar,
thread,
pencil.
Pour hot water into the jar and dissolve rock‑salt in it, knowing that salt's solubility at 100°C in 100 g of water is 42 grams.
After cooling the prepared solution down, immerse the thread in it, tied to the pencil propped against the brim of the jar.
Assign appropriate examples of mixtures to the type of mixture.
water with rock‑salt, vinegar with water, rock‑salt with ground pepper, sulfur dust with iron dust, sand with water, dye for the marker, blue ink, sorrel leaf extract, peas with cabbage, flour with sugar
| Homogeneous mixtures: | |
|---|---|
| Heterogeneous mixtures: |
Conclusion
Mixtures can be separated using various techniques.
Separation methods depend on the type of mixture and they use the properties of its components.
Methods for separating homogeneous mixtures include chromatography.
In order to separate certain mixtures, several techniques must be used. When separating the mixture of rock‑salt and chalk, we should (in turn): dissolve the mixture in water (rock‑salt dissolves), filter it (the chalk will remain on the filter), evaporate the filtrate (rock‑salt remains).
Keywords
extraction, mixture, chromatography
Glossary
chromatografia – metoda służąca do rozdzielania lub badania składu mieszanin związków chemicznych; wykorzystuje różnice szybkości przemieszczania się składników mieszaniny – np.: różnych barwników po pasku bibuły zanurzonym w cieczy (ocet, spirytus, aceton)
ekstrakcja – wyodrębnianie składnika lub składników mieszanin metodą dyfuzji do cieczy lepiej rozpuszczających te związki chemiczne
krystalizacja – polega na wydzieleniu się substancji stałej w postaci kryształów wskutek np. obniżenia temperatury mieszaniny utworzonej przez rozpuszczenie maksymalnej ilości ciała stałego w cieczy
odparowanie – polega na ogrzewaniu ciekłej mieszaniny w celu odparowania cieczy
sączenie (filtracja) – metoda rozdzielania mieszaniny niejednorodnej ciała stałego od cieczy przy użyciu sączka, na którym pozostaje ciało stałe