c8, chemical analysis Flashcards
what is a pure substance
only contains one compound or element throughout, not mixed in with anything else
how can melting or boiling points tell you how pure a substance is
comparing its melting/boiling point to one of a pure substance, the closer the two the purer your sample
what are formulations
formulations are useful mixtures with a precise purpose that are made by following a ‘formula’ (recipe)
each component in a measured quantity
what are the two phases of chromotography
mobile and stationary
what is the mobile phase in chromotography
- where the molecules can move
- always a liquid or gas
what is the stationary phase in chromatography
- where the molecules can’t move
- sold or a really thick liquid
how would you test for chlorine
place damp blue litmus paper on the mouth of the boiling tube
- chlorine will bleach the damp blue litmus paper white
how would you test for oxygen
introduce a glowing splint just inside the test tube and the oxygen will relight it
how to test for carbon dioxide
put bubble gas into the limewater
- causes the solution to turn milky white/ cloudy
how to test for hydrogen
introduce a lit split at the open end of the test tube
- hear a ‘squeaky pop’
what will impurities in a substance do to it’s melting and boiling points
impurities in the sample will lower the mp and increase the bp
resulting in your sample possibly meting and boiling at a range of temperatures
what is a solution
a solute dissolved in a solvent
what is a solute
a substance that is dissolved in a solvent
what is a solvent
a liquid in which chemicals dissolve to make a solution (e.g water, ethanol)
what is chromatography
paper chromatography is a technique for separating components of a mixture between a mobile and a stationary phase
what is the Rf value
the ratio between the distance travelled by the substance (solute) and the distance travelled by the solvent
what is the equation for Rf
distance travelled by the substance / distance travelled by the solvent
what is the solvent front
how far the water travelled up the chromatography paper
how can you use chromatography to see if 2 substances are most likely the same
if 2 substances have the same Rf value under the same conditions (same solvent) then they are probably the same
