LECTURE 10 (Instrumental chemistry) Flashcards
What do extraction, precipitation and distillation have in common?
They separate components between two phases based on differences in the components’ physical properties
What is the difference between extraction, precipitation and distillation?
Extraction = components distributed between two immiscible liquids based on their similarity in polarity to two liquids (like dissolves like)
Precipitation = separation between solid and liquid phases depends on relative solubility in liquid phase
Distillation = separation of mixture liquid phase and its vapour due to relative vapour pressures of components at different temperatures
What can chromotography do?
Separate very complex mixtures composed of many very similar components
Why do components separate in paper chromatography?
Because the different components spend different amounts of time in the “stationary phase” and the “moving phase” depending on their solubility in the solvent
What is Spectroscopy?
The study of the interaction of electromagnetic radiation and matter
What is a Spectrometer?
An instrument which measures and records the wavelengths at which samples emit or absorb light
What are the components of the Spectrometer?
- Source = continuously emits a broad range of wavelengths of light
- Diffraction grating/prism = separates the wavelengths of light by spreading at different angles
- Cell = transparent to the incident light
- Detector = measures the intensity of light beam emerging from the cell
What is Electrophoresis?
Migration of ions in solution under the influence of an electric field
Explanation: Cations move towards the cathode, Anions move towards the anode
What is Retention time?
The time taken for a compound to pass through the apparatus and reach the detector
What does Gas chromatography do?
Check the purity or identity of volatile liquid samples
What are the properties of X-rays?
- Have shorter wavelengths and higher energy than UV radiation
- Generated by deceleration of electrons in matter or by electronic transitions of inner core electrons
What is Mass spectrometry?
A technique for creating gas phase ions from the molecules or atoms in a sample, separating the ions according to their mass-to-charge ratio and measuring the abundance of the ions formed
What is Electrochemistry?
The study of reduction-oxidation reactions in which electrons are transferred from one reactant to another
