Chemical Analysis Flashcards
What colour flame does lithium produce?
Crimson
A crimson flame means which element?
lithium
A lilac flame means which element?
potassium
An orangered / brick red flame means which element?
calcium
A yellow flame means which element?
sodium
A green flame means which element?
copper
what colour flame does potassium produce?
lilac
what colour flame does copper produce?
green
what colour flame does sodium produce?
yellow
what colour flame does calcium produce?
crimson
which metals give a white precipitate when a hydroxide is added?
aluminium, calcium and magnesium
which metal gives a green precipitate when a hydroxide is added?
iron 2
which metal gives a blue precipitate when a hydroxide is added?
copper 2
which metal gives a brown precipitate when a hydroxide is added?
iron 3
what colour precipitate is produced when hydroxide is added to aluminium?
white
what colour precipitate is produced when hydroxide is added to copper 2?
blue
what colour precipitate is produced when hydroxide is added to calcium?
white
what colour precipitate is produced when hydroxide is added to magnesium?
white
what colour precipitate is produced when hydroxide is added to iron 2?
green
what colour precipitate is produced when hydroxide is added to iron 3?
brown
How do you distinguish between aluminium, calcium and magnesium
AlOH precipitate dissolves to form a colourless solution when more NaOH is added
MgOH and CaOH remain unchanged
How do you test for a carbonate ion?
acid (usually dilute HCl but any works) added to test compound
CO2 bubbles
limewater test
how do you test for copper?
green flame
blue precipitate when hydroxide added
how do you test for calcium?
crimson flame
white precipitate when hydroxide added
how do you test for aluminium?
white precipitate when hydroxide added. when more is added it dissolves to form a colourless solution
how do you test for iron 2?
green precipitate when hydroxide added
how do you test for iron 3?
brown precipitate when hydroxide added
how do you test for sulfate ions?
barium ions react with sulfate ions to form
white precipitate:
add a few drops of dilute HCL
add a few drops of dilute BaCl
how do you test for halide ions?
add silver nitrate
which halide ion produces white ppt when silver is added?
chloride
which halide ion produces cream ppt when bromide is added?
bromide
which halide ion produces yellow ppt when silver is added?
iodide
what colour ppt is produced when silver nitrate is added to bromide?
cream
what colour ppt is produced when silver nitrate is added to iodide?
yellow
what colour ppt is produced when silver nitrate is added to chloride?
white
what are the problems with simple tests?
not very sensitive
subjective-> false positives
can’t cope w/ mixtures
not quantitative
slow, one at a time
give an example of an instrumental method for chemical analysis
flame emission spectroscopy-
uses a prism to split wavelengths from a flame
each element has a unique series of wavelengths
what are the advantages of instrumental methods?
can do dilute solutions and mixtures
objective; is there or not
v. sensitive
quantitative
can be automated
disadvantages of instrumental methods?
expensieve, needs calibration, needs training
