Tests for Gases, Anions and Cations Flashcards
What are the four common gas tests?
Hydrogen, Carbon Dioxide, Oxygen, Chlorine
Hydrogen Test
Squeaky Pop Test
Put a lit splint in the area and if there is hydrogen there will be a pop
Carbon dioxide test
Cloudy limewater
Bubbling Carbon dioxide through will cause limewater o turn cloudy
Oxygen tests
A glowing splint will relight if oxygen is present
Chlorine
Bleaches litmus paper
What do tests for anions often give?
Precipitates
What do dilute acids detect?
Carbonates
Test for carbonates
Add a dilute acid to the sample and connect the test tube to a test tube containing limewater. If positive the limewater will go cloudys
What is a carbonate
Substance that contains CO3 2- ions
What is a sulphate
SO4 2-
Test for sulphates
Add hydrochloric acid and barium chloride solution to the sample
If positive a white precipitate will form
Test for hallides
Add nitric acid and silver nitrate solution to solution which will form a precipitate if positive (white, cream or yellow)
Positive Chloride test
White precipitate
Positive bromide test
Cream precipitate
Positive iodide test
Yellow
Test for metal ions
Flame test
Lithium Flame
Crimson flame
Sodium Flame
Yellow flame
Potassium Flame
Lilac flame
Calcium Flame
Orange-Red flame
Copper flame
Green flame
Metals+NaOH =?
Coloured precipitate
Calcium precipitate colour
white
Copper precipitate colour
blue
Iron (II) precipitate colour
Green
Iron (III) precipitate colour
Brown
Aluminium precipitate colour
White but redissolves
Magnesium precipitate colour
White
What is Flame Emission Spectroscopy?
When a sample is placed in a flame and electrons transfer light energy, which passes through a spectroscope. This detects different wavelengths of light. As no two ions contain the same charge and electron arrangement, they produce unique wavelength patterns
Why use Flame Emission SPectroscopy?
Can detect mixtures
Very sensitive
Very fast
Accurate
Uses small samples
Acromyn to remember flame tests
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