C4.2 Identifying Products Of Chemical Reactions

Test using limewater, mixture of calcium hydroxide solution Bubbling carbon dioxide through limewater Goes cloudy white

Damp blue litmus paper Paper turns red then white (Also never say “chlorine ions”, chlorine is an element, “chloride ions”.) Anion test: Add few drops of silver nitrate solution and white precipitate should form

Lit splint in test tube Squeaky pop

Glowing splint relights when put near mouth of the test tube

When metal ions are heated energy is transferred to their electrons This makes them move to higher electron shells When they move back to their normal electron shells energy is transferred to the surroundings as radiation seen as light Different metal ions produce different colours of light

Ion: Li+ Flame: Red or crimson Sodium hydroxide test: N/A

Ion: Na+ Flame: yellow Sodium hydroxide test: N/A

Ion: K+ Flame: lilac Sodium hydroxide test: N/A

Ion: Ca2+ Flame: orange-red Sodium hydroxide test: White precipitate

Ion: Cu2+ Flame: green-blue Sodium hydroxide test: Blue precipitate

Clean nichrome wire loop before test by dipping in hydrochloric acid Rinse with distilled water Dip clean loop in test powder or solution Hold above a roaring flame Clean for each test

Group 1 hydroxides are soluble in water but most other metal hydroxides are insoluble Different metals produce different coloured precipitates Add a few drops of sodium hydroxide solution to a solution containing metal ions

Ion: Fe2+ Flame test: N/A Sodium hydroxide test: green precipitate

Ion: Fe3+ Flame test: N/A Sodium hydroxide test: orange-brown precipitate

Ion: Zn2+ Flame test: N/A Sodium hydroxide test: white precipitate

Zinc hydroxide dissolves to form a colourless solution

Add dilute HYDROCHLORIC ACID to remove any carbonate ions Then add few drops of BARIUM CHLORIDE solution (BaCl2(aq)) White precipitate if sulfate ions are present Example: BaCl2(aq) + K2SO4(aq) -> 2KCl(aq) + BaSO4 Ionic equation: Ba 2+(aq) + SO4 2-(aq) -> BaSO4(s)

Add metal carbonate to dilute acid Bubbles of carbon dioxide gas will be produced Check by bubbling the carbon dioxide through limewater Metal carbonate + acid -> salt + water + carbon dioxide Example: MgCO3(s) + 2HCl(aq) -> MgCl2(aq) + H2O(l) + CO2(g) Ionic equation: CO3 2- + 2H + -> CO2 + H2O

Add a few drops of nitric acid Add few drops of silver nitrate solution (AgNO3(aq)) If chlorine: Cl: white precipitate If bromine: Br: cream precipitate If iodine: I: yellow precipitate Example: NaCl(aq) + AgNO3(aq) -> NaNO3(aq) + AgCl(s) Ionic equation: Ag +(aq) + X -(aq) -> AgX(s)

Relies on a machine to carry out an analysis of a substance Can analyse very small amounts of substances if difficult to obtain, very sensitive Very accurate results, calibrated using international standards Instruments can carry out analyses quickly and they can run all the time

Each peak represents a substance present in the mixture Areas under each peak show the relative amount of each substance in the mixture Retention time for a substance to travel through the chromatography column is different for different substances

Can measure masses of atoms and molecules Used to analyse relative amounts of different isotopes of an element and structure of molecules Used to detect toxic substances Harmful as it ionises the sample and breaks it down into fragments Each peak represents a fragment of the molecule Peak on the far right represents the molecular ion Molecular ion peak = relative formula mass of the molecule