Test For cations and anions Flashcards
What are anions?
Anions are negative ions
Non metal ions
Gained electrons
What are cations?
Positive ions
Metal ions
Lost electrons
How is ammonium made?
By the haber process
How do you do a flame test?
1) clean a nichrome wire by putting in a Bunsen flame and then into hydrochloric acid
2) dip the nichrome into powdered substance
3) put in a blue Bunsen flame and observe colour of flame
What ions are present with a lilac flame?
Potassium ions (K+)
What colour is the flame in a flame test if calcium (Ca2+) ions are present?
Brick red
What ions are present if the flame goes a crimson/dark red colour ?
Lithium ions (Li+)
What colour flame does sodium (Na+) ions show in a flame test?
Yellow/orange
How do you test for ammonium ions?
- Add sodium hydroxide to sample and gently heat it
2. Put Damp red litmus paper in and if it goes blue ammonium ions are present
What colour does red litmus paper turn if ammonium ions are present?
Blue
What is a precipitate?
Insoluble solid formed from 2 aqueous solutions
How do you so a precipitation reaction to test for cations?
- Add sodium hydroxide into a text tube with solution
2. See if a precipitate forms
If copper ions are present what colour will the precipitate be?
Blue
Does iron (II) or iron (III) produce a red/ brown precipitate?
Iron (III)
What colour precipitate is formed when iron (II) ions are present?
Dark green
What is the definition of an ion?
Substances that have been given a charge by either gaining or losing electrons which gives them either a positive or negative charge
How do you test for sulphate ions?
- Add hydrochloric acid to a test tube with the sample
- Add few drops of barium chloride
- shake gently
What is the formula for sulphate ions?
SO4
What is formed when barium chloride is added to hydrochloric acid?
Barium sulphate
What colour is the precipitate formed when sulphate ions are present?
White precipitate
How do you test for halide ions?
- Add few drops of nitric acid to test tube
- Add few drops of silver nitrate
- Gently shake
What colour is the precipitate when chloride (Cl-) ions are present?
White
do bromide ions form cream precipitate or a yellow precipitate?
Cream precipitate formed when bromide ions are present
What colour is the precipitate formed when iodide ions are present?
Yellow
How do you test for carbonate ions?
- Add dilute hydrochloric acid to test tube with sample
2. if carbonate ions are present carbon dioxide releases
How can you tell if carbon dioxide is produced?
Carbon dioxide turns limewater cloudy or milky
What is the formula for carbonate ions?
2-
CO3
