Flame Test
What needs to be done before starting the flame test
Wear goggles and lab coat
Flame colour of sodium?
yellow/orange
How to test oxygen
glowing splint relights
What can you observe if you burn a magnesium ribbon?
bright white flame
What should be used to test lithium carbonate?
bunsen burner, nichrome wire, concentrated hydrochloric acid
What needs to be added to the metal before the test?
concentrated hydrochloric acid
Flame colour of calcium?
brick-red / orange-red
How to test ammonium ion?
+NaOH, + damp red litmus paper
What is ground state and excited state?
ground state: lowest possible level
excited state: higher energy level
potassium
Name the wire used to obtain the sample
clean metal wire (platinum or nichrome) or silica rod
Flame colour of barium
apple green
What substance can react with ammonia to form white smoke?
HCl gas (or concentrated hydrochloric acid)
Why magnesium has no flame colour?
the electron transition in magnesium corresponds to a wavelength outside the visible spectrum
How does the presence of magnesium affect the appearance of the flame colours of caesium?
No change
What impurities does many metal compounds contain and how will it affect the result?
Sodium which may hide other colors
Flame colour of rubidium
red/purple
Describe how will you test strontium ion?
flame test - crimson red
(needs to describe the process of flame test)
If there is impurities of sodium in the sample, what can you do to reduce the effect of sodium?
See through a blue glass (so the yellow light will be absorbed)
Why carrying out the flame test on a mixture of potassium chloride and stronium chloride cannot show the two different ions are present?
The crimson red will mask the lilac colours
Why we say some traditional descriptions of colours are problematic?
describing colours with words is subjective
Flame colour of caesium?
blue/violet
Why we dip the nichrome in acid then heat it before conducting a flame test of a new solution? Why we then dip it in concentrated HCl?
To create volatile chloride
What causes the colours in flame tests?
electron transition
Why the wire used in flame test is made of nichrome not iron? Give two reasons
nichrome has no flame colours and is unreactive