chemical analysis 3.5 Flashcards
chromatography
a technique used to separate the components present within a mixture, chromatography separates the substances by making use of differences in their polarity, solubility or molecular size
different peaks in a chromatography graph means…
different substances
the higher the peak on a chromatography graph means…
the higher the concentration
methods for the collection of gases
gas syringe and collecting gas over water
gas syringe
this is useful for soluble gases, but can be used for all gas collection
collecting gas over water
this is useful for insoluble gases only
safe methods for heating
bunsen burners, hot water baths and heating mantles
bunsen burner
can’t be used if any of the substances are flammable
water baths
are safe to use with flammable substances and stay at relatively low temperatures
heating mantles
safe to use with flammable substances, it’s easier to change the temperature and the temperature is relatively high
volumetric analysis
beakers, measuring cylinders, burettes, pipettes and volumetric flasks
beaker
provide only a rough indication of volume
measuring cylinder
sufficient accuracy for preparative work
burettes, pipettes and volumetric flasks
more appropriate for analytical work
preparation of a standard solution
- weight out the mass of solute you require into a beaker using a mass balance
- dissolve this in a small volume of water
- transfer this into a volumetric flask and transfer rinsings from beaker into the flask
- make the solution up to the mark using a droper
