Understanding Pure Substances and Chromatography in Chemistry
This page introduces fundamental concepts in chemistry, focusing on the nature of pure substances and the technique of chromatography. It provides essential definitions and explanations crucial for understanding chemical composition and separation methods.
Definition: Pure substances contain only one type of element or compound and are in their natural state without any additions.
The page distinguishes between elements, compounds, and mixtures:
- Elements are composed of one type of atom.
- Compounds consist of two or more elements chemically joined together.
- Mixtures contain two or more elements or compounds that are not chemically bonded.
Vocabulary: Formulations are specific mixtures of compounds or substances that do not react together but produce a useful product for a particular function, such as deodorants or sunscreams.
The concept of chromatography is introduced as a method to separate mixtures of soluble substances. It involves two phases: mobile and stationary.
Highlight: In chromatography, pure substances produce a single spot, while impure substances result in two or more spots.
The page also explains the calculation of Rf values in chromatography:
Rf = distance travelled by substance / distance travelled by solvent
An illustration demonstrates the chromatography process, showing the separation of different colored inks on chromatography paper.
Example: A chromatography setup is shown with blue, green, yellow, and black ink spots separated on paper, with the solvent front reaching 10cm and one substance traveling 8cm.
