Gareth Price Flashcards
What needs to be considered when formulating the problem?
Cost Convenience Ease of analysis Time available Equipment Personnel
How would you get statistically valid results?
Take several samples
What needs to be considered when calculating the result?
Express concentration in appropriate units
Appropriate sig figs
Appropriate uncertainty
Define accuracy
How close is the result to the true value
Define precision
How close together are repeat measurements
Is chromatography qualitative or quantitative ?
Qualitative
What does all chromatography depend on?
A compound being distributed between two phases
How does chromatography work?
Different components interact with solids to different extents so they move at different rates
What is the term used to describe the distribution of a component between two phases?
Phase equilibrium
What is he IUPAC definition of chromatography?
A physical ,ethic of separation in which the components to be separated are distributed between two phases, one of which is stationary while the other is mobile and moves in a definite direction
What are two properties of gas chromatography ?
- A large range of samples can be analysed as long as they are volatile and stable
- Uses an inert gas to carry sample over various types of stationary phase - solid or liquid coated onto a solid
What effects can we exploit to separate compounds?
Solubility Ionic interactions Van der Waals forces Hydrogen bonding Size Shape
How are samples separated in gas chromatography?
Their boiling points
How they interact with the stationary phase in the column
How can separation occur with solid stationary phases?
Different condensation / evaporation rates
Different interaction with polar groups
How can separation occur with gas liquid chromatography?
Differing solubility to liquid
