C4 Flashcards
Why use instrumental analysis? Why not?
A : Is faster and more accurate.
Is more sensitive.
D : Requires specialist knowledge. Expensive.
What does the word precipitate mean?
The solid formed as two liquid solutions react.
Which anions do you need to test for?
Carbonate, chloride, bromide, iodide, and sulfate.
How do you test for carbonate ions?
Add dilute acid to the sample. The solution will effervesce; this gas should be bubbled through limewater. If the limewater turns cloudy, then carbonate ions are present.
How do you test for halide ions?
Add dilute nitric acid, then silver nitrate.
What does a positive result for iodide ions look like?
Yellow precipitate.
What does a positive result for bromide ions look like?
Cream precipitate.
What does a positive result for chloride ions look like?
White precipitate.
How do you test for sulfate ions?
Add dilute hydrochloric acid to the sample.
Then add barium chloride or barium nitrate.
A white precipitate should be produced.
Which cations do you have to test for to pass these exams
Calcium, Copper, Iron (ii) and Iron (iii), Zinc.
How do you test for cations?
Add sodium hydroxide solution.
What does a positive result for calcium look like in a sodium hydroxide test?
White precipitate that does not dissolve in excess sodium hydroxide.
What does a positive result for iron (ii) look like?
A green precipitate that does not dissolve in excess.
What does a positive result for copper look like in a sodium hydroxide test?
A light blue precipitate that does not dissolve in excess.
What does a positive result for iron (iii) look like?
A red-brown precipitate that does not dissolve in excess.
What does a positive result for zinc look like?
White precipitate that dissolves in excess.
WHAT IS THE CHEMICAL RAINBOW
LITHIUM, CALCIUM, SODIUM, BARIUM, COPPER, POTASSIUM
