Chromotography & Earths Resources Topic Flashcards
What is a pure substance
Single element or compound
How to work out purity
Pure substances have exact and specific melting and boiling points. The closer the values of your experiment are to those in a data book, the greater the purity of a sample.
How do impurities affect the boiling point
They increase the boiling point and widen the range of temperatures at which a sample will boil
How do impurities affect melting point
Impurities lower the melting point of a sample and widen the range of temperatures at which the sample will melt
What are formulations
Mixture of chemical components that are designed to create useful products
Examples of formulations
Fertilisers
Medicines
Metal alloys
Cleaning agents
Fuels
What are the 2 phases in chromatography
Substances are picked up and carried by a mobile phase (liquid or gas).
The mobile phase then moves through a stationary phase (solid or viscous liquid).
How does the separation of a substance depend on the distribution of a substance?
A substance moves far if it’s more attracted to the mobile phase.
A substance didn’t move far if it’s more attracted to the stationary phase.
How many chromatography spots are produced by pure samples?
1 because they consist of only a single element or compound
How does solubility effect distance traveled of components in chromatography?
The components that travel the furthest are highly soluble (dissolve easily) in the solvent. They are minimally attracted to the chromatography paper.
What is a chromatogram?
Chromatography uses chromatograms. We use them to identify compounds in mixture by calculating Rf values.
What are Rf values?
Rf = distance travelled by substance/distance travelled by solvent.
We can work this out for both referenced substances and tested substances.
What do Rf values depends on
The solvent
What does Rf stand for
Reference substances
This is a pure sample that’s rub next to the tested substance to see if it’s a component in the mixture.
What do you need to do to make potable water?
Drastically reduce the number of microbes found in it. Reduce concentrations of dissolved minerals and salts found in the water.
