C3 Analysis Flashcards
What are the distinctive colours in the flame tests of lithium, sodium, potassium, calcium and barium compounds?
lithium compounds result in a crimson flame
sodium compounds result in a yellow flame
potassium compounds result in a lilac flame
calcium compounds result in a red flame
barium compounds result in a green flame.
What happens when you add sodium hydroxide solution to solutions containing aluminium, calcium and magnesium ions?
Aluminium, calcium and magnesium ions form white precipitates of the metal hydroxide solids
Write ionic equations for the reactions when you add sodium hydroxide solution to solutions containing aluminium, calcium and magnesium ions
Al3+(aq) + 3OH-(aq) → Al(OH)3(s)
Ca2+(aq) + 2OH-(aq) → Ca(OH)2(s)
Mg2+(aq) + 2OH-(aq) → Mg(OH)2(s)
Which of the ions when you add sodium hydroxide solution to solutions containing aluminium, calcium and magnesium ions reacts further with excess sodium hydroxide solution?
Only the aluminium hydroxide precipitate dissolves in excess sodium hydroxide solution
Al(OH)3(s) + OH-(aq) → [Al(OH) 4]- (aq)
What happens when you add sodium hydroxide solution to Copper(II), iron(II) and iron(III) ions?
They form coloured precipitates with sodium hydroxide solution. Copper forms a blue precipitate, iron(II) a green precipitate and iron(III) a brown precipitate.
Write ionic equations for the reactions when you add sodium hydroxide solution to Copper(II), iron(II) and iron(III) ions
Cu2+(aq) + 2OH-(aq) → Cu(OH)2(s) (blue)
Fe2+(aq) + 2OH-(aq) → Fe(OH)2(s) (green)
Fe3+(aq) + 3OH-(aq) → Fe(OH)3(s) (brown)
What happens when dilute acids are added to metal carbonate powders or solutions?
Carbonates react with dilute acids to form bubbles of carbon dioxide.
How would you prove the identity of the compoundwhen dilute acids are added to metal carbonate powders or solutions
Carbon dioxide produces a white precipitate with limewater. This turns limewater milky.
How would you test for the presence of halide ions in solution?
Halide ions in solution produce precipitates with silver nitrate solution in the presence of dilute nitric acid.
How would you identify which halide you had?
Silver chloride is a white precipitate, silver bromide is cream and silver iodide is yellow.
Write ionic equations for the reactions you test for the presence of halide ions in solution
Ag+(aq) + Cl-(aq) → AgCl(s) (white)
Ag+(aq) + Br-(aq) → AgBr(s) (cream)
Ag+(aq) + I-(aq) → AgI(s) (yellow)
Why is dilute nitric acid added to the solution before the silver nitrate solution in a test for a halide?
The acid reacts with any carbonate present. Silver carbonate is a white solid and it would give a false positive in the test.
How would you test for the presence of sulphate ions in solution?
Sulphate ions in solution produce a white precipitate with barium chloride solution in the presence of dilute hydrochloric acid.
Write an ionic equation for the reaction to test for the presence of sulphate ions in solution
Ba2+(aq) + SO42-(aq) → BaSO4(s) (white)
How would you measure the volumes of a strong acid and alkali reacting together?
By titration. The alkali is pipetted into a conical flask. A suitable indicator is added. The acid is added carefully from a burette until the indicator shows that the solution is just neutralised.
