Topic 4: Inorganic Chemistry and the Periodic Table Flashcards
Flame test: Sodium
yellow
Flame test: Potassium
lilac
Flame test: Calcium
yellow-red
Flame test: Barium
pale green
Flame test: lithium
red
Flame test: strontium
Crimson
Flame test: Rubidium
red-violet
what observation is made when dilute, aqueous sodium hydroxide is added to aqueous iron (II)
green precipitate
what observation is made when dilute, aqueous sodium hydroxide is added to aqueous iron (III)
red brown precipitate
what is the test for halides
make a solution of the halide
add dilute nitric acid
add silver nitrate solution
observe colour of precipitate formed
colour of precipitate formed by chloride ions
white precipitate
colour of precipitate formed by bromide ions
cream precipitate
colour of precipitate formed by iodide ions
yellow precipitate
after testing for a halide, ammonia solution can be added. describe the observations when dilute ammonia solution is added.
chloride- precipitate dissolves (soluble)
bromide- precipitate partially dissolves (insoluble)
iodide- precipitate doesn’t dissolve (insoluble)
after testing for a halide, ammonia solution can be added. describe the observations when concentrated ammonia solution is added.
chloride- precipitate dissolves
bromide precipitate dissolves
iodide- precipitate doesn’t dissolve
why does a precipitate form when testing for a halide with aqueous silver nitrate?
solid silver halide forms
write an ionic equation between the reaction of a halide and silver nitrate solution
Ag+(aq) + Br−(aq) → AgBr(s)
The dilute nitric acid is necessary to avoid a false positive in the presence of another anion. Identify this anion and explain why it would result in a false positive. [2]
Carbonate / CO32− [1] Silver carbonate is insoluble [1]
test for sulphate ions
make solutions of sulphate
add dilute hydrochloric acid
add barium chloride solution
white precipitate
observations of halides with concentrated sulfuric acid and the reaction products
chloride- steamy fumes (HI)
bromide- steamy fumes, brown vapour (HBr, Br₂, SO₂)
iodide-steamy fumes, purple vapour, black solid, yellow solid (HI, I₂,S, H₂S)
in cold dilute alkali bromine disproportionates.
write an ionic equation for this reaction
Br2(aq) + 2OH−(aq) → Br−(aq) + BrO−(aq) + H2O(l)
Potassium iodide reacts with concentrated sulphuric acid in two stages, the first of which can be represented by the following equation: KI(s) + H2SO4(l) → HI(g) + KHSO4(s)
i. Write an equation for the next stage of the reaction
8HI + H2SO4 → 4I2 + H2S + 4H2O
Test for ammonium ions
Add aqueous sodium hydroxide
(Warm)
Hold damp red litmus paper over tube
Turns blue
