Zusammenfassung der Ressource
Elements, Compounds
and Mixtures
- Diatomic Molecules - two atoms which bond together COVALENTLY
- High melting point - means STRONG BONDS between particles
- Alloy - mixture of two or more elements at LEAST ONE OF WHICH IS A METAL
- HPLC - High Performance Liquid Chromatography
- Retention Time - the time each COMPONENT spends in the COLUMN
- Elements
- Only ONE type of atom
- Cannot be simplified by chemical means
- Two main kinds - metals and non-metals
- Mixtures
- ORIGINAL properties of components REMAIN
- Have VARIABLE COMPOSITION
- Formation involves NO ENERGY CHANGE
- Compounds
- Two or more elements CHEMICALLY JOINED TOGETHER
- Made by CHEMICAL REACTIONS
- Have properties DIFFERENT FROM REACTANTS
- Filtration - can be used to separate an INSOLUBLE LIQUID from a LIQUID
- Recrystallisation/Evaporation - can be used to separate a SOLUTE from a SOLVENT
- Simple Distillation - used to separate a SOLVENT from the SUBSTANCES DISSOLVED IN IT
- Fractional Distillation - used to separate MISCIBLE LIQUIDS with DIFFERENT BOILING POINTS
- Separating Funnel - used to separate IMMISCIBLE LIQUIDS
- Chromatography - used to separate SOLUBLE SUBSTANCES which are VERY SIMILAR
- Mass Spectrometers determine how heave the molecule is, and how it breaks up
- Ability to identify a substance and ensure its purity is important -
- to ensure purity of raw materials
- to check for adherence to claim on labels
- in drug design and manufacture
- to identify confiscated drugs and contraband
- to forensic scientists
- Area under the peak in HPLC is proportional to the amount of the COMPONENT in the MIXTURE, and is used to monitor the concentration -
- in drug testing in sport
- in environmental monitering
- in petrochemical industry
- in chemical, medical and biological research
- Advantages of Instrumental Analysis -
- Disadvantages of Instrumental Analysis -
- Instruments are extremely expensive
- Highly skilled chemists are required to use them
- Some compounds cannot be detected
- Can use minute samples
- Fully automated
- Almost 100% accuracy