C3 Analysis Flashcards
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)
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)
If you had no indicator, what device could you use to measure the pH?
A pH meter or a pH sensor on a data-logger.
What equation could you use to find the number of moles of a substance in solution?
Moles = concentration x volume in dm-3
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.
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 identify which halide you had?
Silver chloride is a white precipitate, silver bromide is cream and silver iodide is yellow.
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.
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 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)
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.
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.
If you know the concentration of the alkali, how would you find the concentration of the other reactant?
the results of a titration can be used to find the concentration of the other reactant.
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.
