C8 Identifying Ions Tests Flashcards
Learn colours and tests for each ion (27 cards)
Flame test: Copper
Green
Flame test: Lithium
Red
Flame test: Potassium
Purple/lilac
Flame test: Calcium
Orange
Flame test: Sodium
Yellow
How does flame emission spectroscopy work?
Sample placed in flame
Ions heat up — electrons become excited
When they drop to their original levels they transfer energy as light
Spectroscope detects different wavelengths
Each combination can be used to identify ions and calculate their concentrations
Test for Calcium
Add Sodium Hydroxide (NaOH (aq) )
Test for calcium result
White precipitate
Test for copper
Add Sodium Hydroxide (NaOH (aq) )
Test for copper result
Blue precipitate
Test for iron II
Add Sodium Hydroxide (NaOH (aq) )
Test for iron II result
Green precipitate
Test for iron III
Add Sodium Hydroxide (NaOH (aq) )
Test for iron III result
Brown precipitate
Test for aluminium
Add Sodium Hydroxide (NaOH (aq) )
Test for aluminium result
White precipitate that redissolves in excess NaOH to form a colourless solution
Test for magnesium
Add Sodium Hydroxide (NaOH (aq) )
Test for magnesium result
White precipitate
Test for carbonates
React substance with an acid and bubble gas produced through limewater
Test for carbonates result
Carbon dioxide gas produced so when bubbled through lime water it goes cloudy
Test for halides
Add nitric acid and silver nitrate solution
Why not use hydrochloric acid in the halide test?
Hydrochloric acid contains chloride ions which would always cause a positive result
Test for halide: chloride result
White precipitate
Test for halides: bromide result
Cream precipitate
