ch6-chemical analysis Flashcards
whatre mixtures
2 or more elements that ARENT chemically combined
whatre the 4 physical ways of seperating mixtures
1-filtration
2-crystalisation
3-distilation
4-chromotography
whatre the 2 types of distilation
fractional and simple
whatre the differences between fractional and simple distilation
they both use a condenser (surrounded by cool water) but simple is used to seperate solid from liquid while fractional is used to seperate 2 liquids with different boiling points
when is filtration used
to seperate insoluble solids from a liquid
when is crystalisation used
to seperate a soluble solid from a liquid by heating the liquid which evaportaes away from the solid thats colleted at the beaker
why is paper chromotography used
to identify pure substances from mixtures and analyse unkknown substances in solutions
descrube the method of paper chromotography
1- draw a starting line in pencil (cause it wont dissolve) on the bottom of the paper
2-place 2 dots woth different colors
3-place paper in solvent
4-pure substances will produce 1 dot while mixtures will produce more than 1
5-calculate rf value
what happens in paper chromotography if a substance is more soluble
itll move farther up the paper and be in mobile phase for longer
what is in stationary phase and whats in mobile phase
mobile- solvent since its continuesly moving
stationary-paper since it doesnt move
how do we calculate rf values from chromorography
distance traveled by substance/distance traveled by solvent
why do we use rf values
to identify different substances thatre matched against databases
what are the characteristics of ammonia
sharp chocking smell
whats the positive test for ammonia
damp red litimus paper turns blue and white smoke of ammonium chloride when near hydrogen chloride gas (from hcl)
whats type of white smoke is released when ammonia is held near hyrodgen chlorine gas (from hcl)
ammonium chlride smoke
