year 12 chemistry unit 3 – aos 1 chemical analysis
TRANSCRIPT
Year 12 Chemistry
Unit 3 – AOS 1 Chemical Analysis
Quantitative and Qualitative Analysis
• Qualitative Analysis: - Identification of chemicals present
• Quantitative Analysis: - Identification of how much of each chemical is present
Physical Properties
• Physical Properties: - Colour, mass, solubility, melting point, response to electromagnetic radiation.
• Chemical Properties: - reactions with acids, bases, oxidants or reductants, precipitates.
• Gas Chromatography – Nick & Arafath• High Performance Liquid Chromatography – Thilag
& Stephen• UV-Visible Spectroscopy – Pricilla, Maria, Samira • Atomic Absorption Spectroscopy – Mae & Claire• Infra-Red Spectroscopy – Sandip, Amy & Jocelyn• Nuclear Magnetic Resonance Spectroscopy – Sahil
& James• Mass Spectroscopy– Sandip, Amy & Jocelyn
Types of Analysis
Gas Chromatography (GC) Description
Stationary Phase: Gel coated solidMobile Phase: GasA sample is injected into a column with a carrier gas. The components of the sample travel through the column at different rates to a flame.
Basic TheoryComponents of a sample move at different rates through a column. Qualitative results based on rt.. Once the components have been separated a quantitative results can be obtained based on the flame responds to the material.
Gas Chromatography (GC)Major Uses
Provides both qualitative and quantitative analysis of compounds with a molar mass of less than 300. Compounds must be easily vapourised, without decomposing. Used for analysis of blood and urine for the presence of drugs
Typical Analyte:Low molecular mass compounds
Typical Sample:Foods, drugs, biological samples
Advantages:Highly sensitive and precise
Disadvantages:Moderately expensive
Gas Chromatography
High Performance Liquid Chromatography (HPLC)
DescriptionStationary Phase: Gel covered solidMobile Phase: SolventA sample is injected into a column under high pressure, The components of the sample travel through the column at different rates.
Basic TheoryComponents of a sample move at different rates through a column. Qualitative results based on rt..
High Performance Liquid Chromatography (HPLC)
Major UsesProvides both qualitative and quantitative analysis of large molecular substances. Ideal for identifying compounds that do not vaporise or will decompose. Used for the analysis of proteins and organic compounds.
Typical Analyte:Medium to high mass organic compounds
Typical Sample:Foods, drugs, biological samples
Advantages:High sensitivity and precision
Disadvantages: Moderately expensive
High Performance Liquid Chromatography (HPLC)
Ultra-Violet Visible Spectroscopy Description
UV light of a complimentary colour to the colour of the substance tested is passed through the substance to a receiver.
Basic TheoryLight is absorbed by some molecules. The amount of light absorbed is proportional to concentration of the molecule, allowing in quantitative results being obtained.
Ultra-Violet Visible SpectroscopyMajor Uses
Generally used as a quantitative analysis to determine the concentration of organic compounds and metal ions in urine, blood, plastics or water. Can be used as qualitative using the unique spectra as a fingerprint
Typical Analyte:Low mass organic compounds
Typical Sample:Liquid and gas samples
Advantages:Simple to operate
Disadvantages:Not suitable for low concentrations
Ultra-Violet Visible Spectroscopy
Atomic Absorption Spectroscopy (AAS)
DescriptionA light of a specific wavelength is passed through a flame which contains a vaporised sample. The light passes through a wavelength selector to a detector
Basic TheoryWhen a metal atom absorbs energy its electrons will jump to higher energy states. The wavelength of the light absorbed identifies the element, the intensity of the light absorbed identifies the concentration.
Atomic Absorption Spectroscopy (AAS)
Major UsesUsed in quantitative analysis to determine the concentration of metals in blood, urine, air, soil, water and foods. May by used qualitatively to determine the presence of metals.
Typical Analyte:Metals
Typical Sample:Low viscosity solutions
Advantages:Highly sensitive and precise
Disadvantages:Moderately expensive
Atomic Absorption Spectroscopy (AAS)
Infrared Spectroscopy (IR)
DescriptionInfrared light is passed through a sample to a detector. The percentage absorption and wavelength is measured, resulting ina unique IR spectrum.
Basic TheoryFunctional groups absorb infrared light at specific wavelengths. Based on the was the sample responds to IR light the functional groups and overall structure can be identified
Infrared Spectroscopy (IR)Major Uses
Used for qualitative analysis to determine the types of bonds and functional groups present.
Typical Analyte:Organic molecules
Typical Sample:Solids, liquids or gases
Advantages:Huge range of analytes
Disadvantages:Moderately expensive
Infrared Spectroscopy (IR)
Nuclear Magnetic Resonance Spectroscopy (NMR)
DescriptionA sample is placed in a test tube that spins between a powerful magnet. A radio transmitter coil produces a short powerful pulse of radio waves, a radio then detects the radio frequencies emitted from the nuclei as they relax to a lower energy level
Basic TheoryAny atom with an odd number of protons or neutrons will absorb energy, resulting in being in a state of resonance. Atoms in different configurations result in different energy shifts. The resulting shift in energy can be used to identify the configuration of the atom.
Nuclear Magnetic Resonance Spectroscopy (NMR)
Major UsesUsed in qualitative analysis to provide information in the determination of the structure of the carbon-hydrogen backbone of organic compounds
Typical Analyte:Organic molecules
Typical Sample:Liquid or solids
Advantages:Highly sensitive and precise
Disadvantages:Very expensive
Nuclear Magnetic Resonance Spectroscopy (NMR)
Mass SpectroscopyDescription
A gaseous sample is injected into the chamber, where it is ionised. Positive ions are accelerated in a magnetic field. Ions move in a curved path depending on their mass/charge ratio. The detector measures the relative abundance of each m/e ratio.
Basic TheoryCharged particles move in a curved path relative to the mass/charge ratio. Using an ion collector we can detect the amount of ions in each mass/charge ratio. The mass/charge ratios can be compared to a book of data to identify fragments.
Mass SpectroscopyMajor Uses
Used in qualitative analysis to determine the structure and identity of a compound. Can be used in quantitative analysis as a detector for Atomic Emissions Spectroscopy, Gas Chromatography and Liquid Chromatography
Typical Analyte:Any elements/compounds that can be volatised
Typical Sample:Anything that can be volatised
Advantages:Highly sensitive and precise for wide range of analytes
Disadvantages:Expensive and requires training to operate
Mass Spectroscopy