Chemical industry

• CI1 What are 2 features of ammonia?

  colourless gas and strong smell
• CI1 Why is ammonia hard to make?

  nitrogen is a very unreactive gas
• CI1 What are the conditions needed for the Haber process?

  high pressure

  450 °c

  iron catalyst
• CI1 Why is nitrogen gas so unreactive?

  need to break the triple bond which has very high bond enthalpy so needs lots of energy (high temperature and catalyst)
• CI1 Why can ammonia form a dative covalent bond?

  has a lone pair of electrons not used in bonding that can so is a base as can donate the pair of electrons to another atom (proton to form ammonium)
• CI1 What is the equation of making ammonia?

  N₂(g) + 3H₂(g) → 2NH₃(g)
• CI1 What is the equation showing ammonium being formed?

  NH₃(g) + H⁺(aq) ⇌ NH₄⁺(aq)
• CI1How is nitrogen (IV) dioxide made? What is the equation showing this?

  nitrogen (II) oxide formed in combustion process turns to brown nitrogen (IV) dioxide in air

  Nthe ₂(g) + O₂(g) → 2NO(g)

  2NO(g) + O₂(g) → 2NO₂(g
• CI1 What is the sequence of bacteria reducing nitrate (V) ions in anaerobic conditions to form nitrogen gas?

  NO₂⁻(aq) → NO (aq) →N₂O(g) → N₂(g)
• CI1 What are the 2 nitrate ions used in the carbon cycle? How soluble are they in water?

  nitrate (III) - NO₂⁻

  nitrate (v) - NO₃⁻

  they are very soluble in water
• CI1 How are NO₂⁻ and NO₃⁻ made?

  nitrification - oxidation of ammonium ions by aerobic bacteria in soil - to get energy. Ammonium is oxidised to NO₂⁻ which is then further oxidised to make NO₃⁻
• CI1 What is the equation showing the formation of NO₂⁻ from ammonium?

  NH₄⁺(aq) + 1.5O₂(g) → NO₂⁻(aq) + 2H⁺(aq) + H₂O(l)
• CI1 What is the equation showing the formation of NO₃⁻ from further oxidation of NO₂⁻?

  NO₂⁻(aq) + ¹/₂O₂(g) → NO₃⁻(aq)
• CI1 How do you test for nitrate (v) ions?

  NaOH solution and Devarda's alloy (copper, aluminium and zinc) added and gently heated

  aluminium = reducing agent

  if test has nitrate (v) ammonia gas will be produced and turns damp red litmus paper blue

  white fumes of ammonium chloride with hydrogen chloride from gas fumes of hydrochloric acid
• CI1 What is the equation showing test for nitrate (v)?

  3NO₃⁻ + 8Al + 5OH⁻ + 18H₂O → 3NH₃ + 8[Al(OH)₄]⁻
• CI1 How do you test for ammonium ions?

  add NaOH and gently heat. If ammonium ions present, ammonia gas will be made
• CI1 What is the equation showing test for ammonium ions?

  NH₄⁺(aq) + OH⁻(aq) → NH₃(g) + H₂O(l)
• CI3 How are phosphate fertilisers (e.g. ammonium sulfate) made?

  from phosphoric acid which is made from sulfuric acid
• CI3 How is sulfuric acid produced?

  1. extraction of sulfur

  2. conversion of sulfur to sulfur dioxide

  3. conversion of sulfur dioxide to sulfur trioxide

  4. conversion of sulfur trioxide to sulfuric acid
• CI3 What are the uses of sulfuric acid?

  phosphate fertilisers

  making phosphates

  making fibres

  making hydrofluoric acid

  making paints and pigments

  making paper

  metal processing
• CI3 What is the rate of a reaction?

  the rate at which reactants are converted into products
• CI3 What can be used to find the rate of a reaction?

  the concentration of reactants/products
• CI3 How can you measure the rate of a reaction?

  1. the rate of products produced/reagents used up

  2. measuring volume of gases evolved

  3. measuring mass change

  4. pH measurement

  5. colorimetry

  6. chemical analysis (including titration)
• CI3 What does colorimetry do?

  measures colour change of a reaction
• CI3 What is quenching?

  involves taking samples of reaction mixture at regular intervals and stopping the reaction before analysis
• CI3 What are 2 examples of quenching?

  1. acid-catalysed reaction between iodine and propanone. sample extracted and quenched by adding sodium hydrogencarbonate. neutralises the acid catalyst and stops the reaction. unreacted iodine found by titrating with thiosulfate solution

  2. Hydrolysis of methyl methanoate using NaOH. rate measuring by measuring the conc. of NaOH during reaction. samples quenched by diluting with known volume of ice cold water. Conc. of NaOH remaining found by titrating with acid (e.g. HCl)
• CI4 What is the catalyst used to make sulfuric acid?

  vanadium (v) oxide
• CI4 How do you find the initial rate of reaction?

  draw a tangent at t=0 and find the gradient of the line
• Why is the rate of reaction fastest at the beginning?

  the conc. of reactants is at its highest because hasn't been used up yet
• How can you tell when a reaction has stopped from a graph?


  When the curve becomes horizontal and the gradient is 0
• When finding Kc, when do you need to invert units?

  when you cancel out everything on top
• What is a 0 order reaction?

  if you double the concentration of reactants and the rate stays the same
• What is a 1 order reaction?

  if you double the concentration of reactants and the rate doubles
• What is a 2 order reaction?

  if you double the concentration of reactants and the rate quadruples
• How do you find the order of a reaction?

  add together the orders of the reactants

  for example [X]² + [Y]² = 4 the overall order of the reaction is 4
• What is the rate equation for the experiment A + B → C + D?

  rate = K x [A] x [B]
• What is K in the rate equation?

  the rate constant
• What does the rate equation rate = K x [A] x [B]² mean?


  the rate is directly proportional to [A]

  the rate will double if you double [A]

  the rate is directly proportional to the square of [B]

  the rate will quadruple if you double [B]
• What does the order of a reaction tell you?

  how much a reaction is affected by the concentration of reactants
• What are the units of K if the order of the reaction is 0?

  moldm⁻³sec⁻¹