ChemistryCode 5070
Identification of ions and gases
What this topic asks you to be able to do
- Describe the tests used to identify these anions: (a) carbonate, CO3 2–: react it with dilute acid, then test the gas given off for carbon dioxide (b) chloride, Cl –, bromide, Br –, and iodide, I –: acidify with dilute nitric acid and then add aqueous silver nitrate to it (c) nitrate, NO3 –: reduce it using aqueous sodium hydroxide and aluminium foil, then test the gas given off for ammonia (d) sulfate, SO4 2–: acidify with dilute nitric acid and then add aqueous barium nitrate to it (e) sulfite, SO3 2–: react it with acidified aqueous potassium manganate(VII)
- Describe how aqueous sodium hydroxide and aqueous ammonia can be used to recognise the aqueous cations listed here: (a) aluminium, Al 3+ (b) ammonium, NH4 + (c) calcium, Ca2+ (d) chromium(III), Cr3+ (e) copper(II), Cu2+ (f) iron(II), Fe2+ (g) iron(III), Fe3+ (h) zinc, Zn2+
- Describe the tests used to recognise the following gases: (a) ammonia, NH3, with moist red litmus paper (b) carbon dioxide, CO2, with limewater (c) chlorine, Cl2, with moist litmus paper (d) hydrogen, H2, with a lit splint (e) oxygen, O2, with a glowing splint (f) sulfur dioxide, SO2, with acidified aqueous potassium manganate(VII)
- Describe how a flame test is used to identify these cations: (a) lithium, Li+ (b) sodium, Na+ (c) potassium, K+ (d) calcium, Ca2+ (e) barium, Ba2+ (f) copper(II), Cu2+