Chemical Analysis Flashcards
What is a pure substance
A substance that only contains one type of compound only
What is an element made up of
One type of atom
What is a compound made up of
Two or more elements that are chemically bonded
What are mixtures
2 or more elements or compounds that are not chemically bonded
Describe the melting point of a pure substance
Precise - compared to impure substances which can have a broad range
What is a formulation
- Mixture of compounds or substances that do not react together
- producing a useful product with desired characteristics for a particular function e.g. soap
What is paper chromatography doing
Separating a mixture of soluble substances
What are the 2 phases in chromatography
- mobile phase
- stationary phase
What is the mobile phase
- the solvent
- it moves through the paper (stationary phase) carrying the different substances with it
What is the stationary phase
The absorbent paper
What is a chromatogram
What is produced when the two dissolved substances separate
What can we use chromatograms for
Distinguish pure and impure substances apart
- pure = 1 dot
- impure = 2 or more dots
How do you calculate the Rf values
Distance travelled by substance / distance travelled by solvent
What determines how far up the page the dots go
The substance’s solubility
How would you carry out a chromatography
- Use ruler; 1cm up make a dot and draw a line horizontally thru it (in pencil)
- Leaving a gap between each drop, use a pipette to drop each droplets of the ink onto the line you created
- Let paper’s bottom tip just touch the solvent. (Important the solvent doesn’t go over the spots)
- Allow solvent to move up paper
- Before the solvent moves all the way to the top, remove it and allow it to dry
- Once dry, measure distance travelled by solvent
- Measure different travelled by each spot
- Calculate the Rf value of each spot
