Chemical Analysis - HIGHER Only Flashcards
To learn how to analyse different chemicals
What is the test for carbon dioxide gas?
Turns limewater (aqueous calcium hydroxide) milky
What is the test for oxygen gas?
Relights a glowing splint
What is the test for hydrogen gas?
Squeaky pop test
What is the test for chlorine gas?
Red litmus turns blue and is then bleached white
Why colour flame do you get with lithium compounds?
Crimson
Why colour flame do you get with sodium compounds?
Yellow
Why colour flame do you get with potassium compounds?
Lilac
Why colour flame do you get with calcium compounds?
Orange - Red
Why colour flame do you get with copper compounds?
Green
What is an anion?
A negatively charged ion
What is a cation?
A positively charged ion
What colour precipitate do solutions of copper(II) ions form when sodium hydroxide solution is added?
A blue precipitate of Copper (II) hydroxide
What colour precipitate do solutions of iron(II) ions form when sodium hydroxide solution is added?
A green precipitate of iron (II) hydroxide
What colour precipitate do solutions of iron(III) ions form when sodium hydroxide solution is added?
A brown precipitate of iron (III) hydroxide
What is the balanced equation for the reaction of calcium nitrate with sodium hydroxide solution?
Ca(NO3)2 + 2NaOH –> 2NaNO3 + Ca(OH)2
What is the balanced equation for the reaction of aluminium nitrate with sodium hydroxide solution?
Al2(NO3)3 + 3NaOH –> 3NaNO3 + Al(OH)3
What is the balanced equation for the reaction of magnesium nitrate with sodium hydroxide solution?
Mg(NO3)2 + 2NaOH –> 2NaNO3 + Mg(OH)2
a) How can you test for a carbonate?
b) How can the gas produced be tested?
a) React with dilute acids to form carbon dioxide gas.
b) Carbon dioxide gas can then be identified by turning limewater cloudy
1) How can we identify chloride ions in a solution?
2) What colour is the precipitate?
1) Add a few drops of dilute nitric acid
2) Add a few drops of dilute silver nitrate solution
3) Silver chloride is a white precipitate
1) How can we identify bromide ions in a solution?
2) What colour is the precipitate?
1) Add a few drops of dilute nitric acid
2) Add a few drops of dilute silver nitrate solution
3) Silver bromide is a cream precipitate
1) How can we identify iodide ions in a solution?
2) What colour is the precipitate?
1) Add a few drops of dilute nitric acid
2) Add a few drops of dilute silver nitrate solution
3) Silver iodide is a yellow precipitate
1) How can we identify sulfate ions in a solution?
2) What colour is the precipitate?
1) Add a few drops of dilute hydrochloric acid
2) Add a few drops of barium chloride solution
3) Barium sulphate forms a white precipitate
What are the advantages of using instrumental methods to detect elements and compounds compared with the chemical tests
- Speed
- Sensitivty
- Accuracy
What can flame emission spectroscopy be used for?
Data from a spectroscope can be used to:
1) Identify metal ions in a sample.
2) Determine the concentration of metal ions in dilute solutions.
a) What colour precipitate will a solution of magnesium ions form when sodium hydroxide solution is added?
b) What happens when excess sodium hydroxide solution is added?
a) A white precipitate of magnesium hydroxide
b) No change
What is the balanced equation for the reaction of copper (II) nitrate with sodium hydroxide solution?
Cu(NO3)2 + 2NaOH –> 2NaNO3 + Cu(OH)2
What is the balanced equation for the reaction of calcium carbonate with hydrochloric acid?
CaCO3 + 2HCl –> CaCl2 + CO2 + H2O
What is the balanced equation for the reaction of calcium carbonate with sulfuric acid?
CaCO3 + H2SO4 –> CaSO4 + CO2 + H2O
What is the balanced equation for the reaction of calcium carbonate with nitric acid?
CaCO3 + 2HNO3 –> Ca(NO3)2+ CO2 + H2O
How does flame emission spectroscopy work to identify metal ions?
1) A sample is put into a flame
2) The light given out is passed through a spectroscope.
3) The output is a line spectrum that can be compared with known samples.
