chemistry

• Uses for bitumen


  Making roads
• Test fo H2 (hydrogen gas)

  Burns with squeaky pop
• Test for O2 (oxygen gas)


  Relights glowing splint
• Test for CO2 (carbon dioxide gas)

  Turns limewater cloudy (then colourless again)
• Test for Cl2 (chlorine gas)

  Turns damp blue litmus red, then bleaches it
• Test for NH3 (ammonia)

  Turns damp red litmus paper blue
• Test for NH4+ ion (ammonium ion)

  Add NaOH (sodium hydroxide)

  Turns damp red litmus paper blue
• Test for carbon=carbon multiple (double, triple etc.) bond


  Decolourises bromine water (Br2(aq))

  Orange -> colourless
• Test for copper (II) ion (Cu2+)


  Blue precipitate with OH- ion
• Test for iron (II) ion (Fe2+)

  Green precipitate with OH- ion
• Test for iron (III) ion (Fe3+)

  Brown precipitate with OH- ion
• Test for Cl- (chlorine ion)


  Warm with HNO3(aq) (nitric acid)

  Add AgNO3 (silver nitrate)

  White precipitate forms (AgCl/silver chloride)
• Test for Br- (bromine ion)


  Warm with HNO3(aq) (nitric acid)

  Add AgNO3 (silver nitrate)

  Cream precipitate (AgBr/silver bromide)
• Test for I- (iodine ion)


  Warm with HNO3(aq) (nitric acid)

  Add AgNO3 (silver nitrate)

  Yellow precipitate (AgI/silver iodide)
• Test for Li+ (lithium ion)

  Bright red flame test
• Test for Na+ (sodium ion)

  Orange-yellow flame test
• Test for K+ (potassium ion)

  Lilac flame test
• Test for Ca2+ (calcium ion)

  Brick red flame test

  (NB brick red isn't red, looks more orange)
• Test for Mg2+ (magnesium ion)

  No colour change in flame test (specifically no change)
• Test for SO4 2- (sulfate ion)

  Add HCl (hydrocloric acid) and BaCl2 (barium chloride)

  White precipitate forms (BaSO4)
• Test for CO3 2- (carbonate ion)

  Add HCl (hydrochloric acid)

  Produces CO2 - test for CO2 (limewater goes cloudy)
• Test for PRESENCE of water

  Changes anhydrous copper sulfate from white to blue

  CuSO4 + 5H2O -> CuSO4.5H2O (equation must be learnt)
• Test for PURITY of water

  Melting/freezing point at 0°C

  Boiling point at 100°C (BOTH must be used together)
• Nitrates solubility

  All soluble
• Chlorides, bromides, and iodides solubility

  All soluble except silver (AgCl/AgBr/AgI) and lead (PbCl2/PbBr2/PbI2)
• Sulfates solubility


  All soluble except barium (BaSO4) and calcium (CaSO4)
• Carbonates solubility

  All insoluble except sodium (Na2CO3), potassium (K2CO3) and ammonium ((NH4)2CO3)
• Hydroxides solubility


  All insoluble except sodium (NaOH), potassium (KOH) and ammonium (NH4OH)
• Salts with these 3 cations (positive ions) are always soluble:


  Sodium (Na+)

  Potassium (K+)

  Ammonium (NH4 +)
• Which two substances are heated together to produce ammonia in the laboratory?

  Calcium hydroxide and ammonium chloride.
• What are the important properties of ammonia?

  Colourless, pungent gas.

  Less dense than air.
• What is the equation for the reversible reaction which occurs in the "Ammonia Smokescreen" experiment?

  NH3 + HCL = NH4CL
• Which two elements must be reacted together to make ammonia industrially

  Nitrogen and hydrogen.
• What raw material does nitrogen come from?


  Nitrogen comes from the air.
• What is the equation for the exothermic reaction which produces ammonia?

  N2 (g) + 3H2 (g) = 2NH3 (g)
• When is a reversible reaction said to have reached dynamic equilibrium?

  When it is going both ways at the same rate.
• At what pressure is the Haber Process normally done?

  About 200 atmospheres.
• What are the advantages of doing the Haber process under high pressure?

  The reaction is faster.

  The yield of ammonia is higher.
• What is the disadvantage of using too high a pressure?

  Very high pressures are too expensive.
• What problem occurs if the temperature is too low in the Haber process

  The reaction is too slow.