Science - Chemistry - Chemical Analysis - C8 Flashcards
what is purity ?
a substance in its natural state which only contains one type of element
what does a chemically pure substance have ?
a specific melting point
how can you test a a substances purity ?
by measuring its melting/boiling point
what will impurites in substances do ?
lower your melting point and increase the melting range of your substance
increase boiling point over a range of temperatures
what are formulations ?
useful mixtures with a precise purpose made by a formula
give an example of a formula ?
paint
why are formulations important ?
- altering formulations of a pill makes sure that a drug is delivered to the right part of the body
what is chromatography ?
separating substances in a mixture
what are the 2 phases of chromatography ?
mobile phase
stationary phase
what is the mobile phase ?
where molecules can move in a liquid or gas
what is a stationary phase ?
molecules can’t move , can be a thick liquid or solid
what happens in chromatography ?
- substances in the sample moves between the 2 stages
- an equilibrium is formed between the 2 stages
- the mobile phase moves through the stationary phase and anything dissolved in the mobile phase moves with it
what does how quickly a chemical moves depend on ?
it distribution
what is a chemicals distribution ?
whether the chemical spends more time in the mobile or stationary phase
what phase to most components in a substance normally separates in ?
the stationary phase as long as all components spend different amounts of time in the mobile phase
why, in paper chromatography may the number of spots formed change in different solvents ?
the distribution of chemicals is the same in some solvents but different in others
how many spots will a pure substance always form ?
1 spot in any solvent
what is the stationary phase in paper chromatography ?
the filter paper
what is the the mobile phase in paper chromatography ?
the solvent
what does the amount of time spent in each phase in paper chromatography depend on ?
- how soluble they are in the solvent
- how attracted they are in the paper
what stage do molecules with a higher solubility spend longer in ? (paper chromatography)
the mobile phase
what do molecules with higher solubility do in paper chromatography ?
travel up the paper higher and are less attracted to the paper
what is a chromatogram ?
the result of a chromatography experiment
what is the RF value ?
the ratio between the distance travelled by the substance and the distance travelled by the solvent
how do you calculate RF value ?
distance travelled by substance / distance travelled by solvent
what is the test for oxygen ?
it will relight a glowing splint