quiz 5 Flashcards
(16 cards)
During
Chromatograph, explain why the substances are place on a pencil line
Pencil will not dissolve in the solvent
In everyday language,define a pure substance
A substance that has nothing added to it
State the test and result for oxygen
Test: place a glowing splint in the gas
Result:splint relights
Explain how chromatograph can show the difference between pure and impure substances
Pure substances will not separate into a number of different spots
State the test and result for carbon dioxide
Test: bubble the gas through limewater
Result: limewater turns milky
State the variables that a substances Rf value depends on
How soluble the substance is in the solvent
How attracted the substance is to the paper(or other stationary phase)
In chemistry,
define a pure substance
A substance made of single element or compound that is not mixed with anything else
Define formulation
A complex mixture designed as a useful product
State the test and result for chlorine
Test: place a piece of damp litmus paper in the gas
Result: litmus bleaches(turns white)
In paper chromatogaph, identify the stationary and the mobile phase
Stationary phase-paper
Mobile phase-solvent(usually water or ethanol)
State the test and result for hydrogen
Test:place a lit splint near the gas
Result:squeaky pop
Give the equation for Rf value
Rf value= distance moved by the substance divided distance moved by solvent
Give 3 examples of formulations
Fuels
Paints
Medicines
Cleaning agents
Alloys
Fertilisers
Describe how pure substances can be distinguished from impure ones
Pure substances have specific melting and boiling points
Impure substances melt and boil across a temperature range
In chromatograph, explain why the solvent height must be lower than the pencil line
So that the substances dont dissolve off the paper into the solvent
