chemical tests Flashcards
what do flame tests identify
metal ions
in a flame test what colour does lithium go
red flame
in a flame test what colour does sodium go
yellow flame
in a flame test what colour does potassium go
lilac flame
in a flame test what colour does calcium go
orange-red flame
in a flame test what colour does copper go
blue-green
how do you do a flame test
get a clean platinium wire loop by dipping it in diluted hydrochloric acid and holding it in the flame. Once you hold the loop in the flame and it burns without any colour you can dip it in the sample you want to test, then put it over the blue flame to see the colour.
does the flame test test for cations or anions
cations
what do some metals form with NaOH
coloured precipitate
explain how you test for metal ions using sodium hudroxide (NaOH)
add a few drops of sodium hydroxide to the unknown compound in a test tube and if you get a colourd insoluble hydroxide you can tell what was in the compound
what is the precipitate colour of copper(ii)
blue
what is the precipitate colour of iron(ii)
sludgy green
what is the precipitate colour of iron(iii)
red- brown
what is the charge on OH
-
how do you test for ammonia
use red litmus paper and if amonia is present it will turn blue
how do you test for carbonates
add dilute hydrochloric acid to the test sample and if carbonated are present carbon dioxide will be released
how do you test for sulfates
add dilute hydrochloric acid followed by barium chloride solution and a white precipitate should form for a postaive result
how do you test for chloride, bromide or iodide ions (halides)
add dilute nitric acid followed by silver nitrate solution.
what does a chloride ion give
white precipitate of silver chloride
what does a bromide ion give
a cream precipitate of silver bromide
what does a iodine ion give
yellow precipitate of silver choloride
how do you test for chlorine
bleached damp blue litmus paper, turning it white
how do you test for oxygen
re-lights a glowing splint
how do you test for carbon dioxide
turns lime water cloudy
how do you test for hydrogen
skueaky pop test
how do you test for ammonia
turns damp red litmus paper blue
how do you test for water
anhydrous copper (ii) sulfate and see if it turns blue
how do tou test for alkenes
if you add an alkene to bromine water, they will stay orange
