chemistry

• When analysing markets, a range of assumptions are made about the rationality of economic agents involved in the transactions
• The Wealth of Nations was written

  1776
• Rational


  (in classical economic theory) economic agents are able to consider the outcome of their choices and recognise the net benefits of each one
• Consumers act rationally by


  Maximising their utility
• Producers act rationally by


  Selling goods/services in a way that maximises their profits
• Workers act rationally by


  Balancing welfare at work with consideration of both pay and benefits
• Governments act rationally by


  Placing the interests of the people they serve first in order to maximise their welfare
• Groups assumed to act rationally


  • Consumers
  • Producers
  • Workers
  • Governments
• Rationality in classical economic theory is a flawed assumption as people usually don't act rationally
• Marginal utility


  The additional utility (satisfaction) gained from the consumption of an additional product
• If you add up marginal utility for each unit you get total utility
• Elements that form normal oxides

  • Beryllium
  • Magnesium
  • Calcium
• Elements that form peroxides


  • Strontium
  • Barium
• General Reactions for normal oxides

  2M + O2 → 2MO (Where M = Be, Mg, Ca)
• General Reactions for peroxides

  M + O2 → MO2 (Where M = Sr, Ba)
• Reaction with water for alkali metals

  2M + 2H2O → 2MOH + H2 (Where M = Li, Na, K, Rb, Cs)
• Beryllium does not react with either cold or steam, but magnesium reacts with steam
• Reaction with water for alkaline earth metals

  M + 2H2O → M(OH)2 + H2↑ (Where M = Mg, Ca, Sr and Ba)
• Reaction with halogens for alkali metals


  2M + X2 → 2MX (Where M = Li, Na, K, Rb, Cs) & (X = Cl, Br, I)
• Reaction with halogens for alkaline earth metals


  2M + X2 → MX2 (Where M = Be, Mg, Ca, Sr, Ba)
• Reaction with nitrogen for alkali metals

  6M + N2 → 2M3N (M = Li, Na, K, Rb, Cs)
• Reaction with nitrogen for alkaline earth metals


  3M + N2 → M3N2 (M = Be, Mg, Ca, Sr, Ba)
• Reaction with hydrogen for alkali metals

  2M + H2 → 2MH (M = Li, Na, K, Rb, Cs)
• Reaction with hydrogen for alkaline earth metals


  M + H2 → MH2 (M = Ca, Sr, Ba)
• Reaction with alcohols for alkali metals

  2M + 2C2H5OH → 2C2H5OM + H2 (M = Li, Na, K, Rb, Cs)
• Alkaline earth metals have a very limited reactivity with alcohols
• Reaction with acids for alkali metals

  2M + 2HCl → 2MCl + H2 (Where M = Li, Na, K, Rb, Cs)
• Alkaline earth metals can react with acids but their reactivity is generally lower compared to alkali metals
• Flame test


  A qualitative method used to identify the presence of alkali metals based on their characteristic flame colours
• Flame colours of alkali and alkaline earth metals

  • Lithium - Red
  • Sodium - Yellow
  • Potassium - Violet
  • Calcium - Orange red
  • Strontium - Deep Red
  • Barium - Pale Green
  • Beryllium - Blue Violet
  • Magnesium - Silver white
• Beryllium has no characteristic flame colour
• Sodium Hydroxide (NaOH)


  Also known as 'Caustic Soda', it is one of the most important chemicals
• Manufacture of Sodium Hydroxide by Castner-Kellner's Process

  1. Raw Material: 25% (W/W) solution of sodium chloride

  2. Apparatus: Castner-Kellner's cell

  3. Ionization: 2NaCl → 2Na+ + 2Cl-

  4. Reaction at Anode: 2Cl- → Cl2 + 2e-

  5. Reaction at Cathode: 2Na+ + 2e- → 2Na

  6. Reaction in Denuder: 2Na + 2H2O → 2NaOH + H2
• Advantages of Castner-Kellner's Process

  • The process is very efficient
  • The products are of high purity
  • The possible reaction between NaOH and Cl2 is avoided by obtaining NaOH and Cl2 in separated compartment
• Disadvantages of Castner-Kellner's Process

  • This process consumes large amount of electricity
  • Some mercury vapors escapes into environment and producing the pollution of food chains
• The use of Castner-Kellner's process has been banned and is being replaced by Gibb's diaphragm cell process which does not use mercury but gives the products of high purity
• Physical Properties of Sodium Hydroxide (NaOH)

  • State: Solid at room temperature
  • Odor: Odorless
  • Melting Point: Approximately 318°C
  • Solubility: Highly soluble in water
  • Density: Approximately 1.52 g/cm³ for 50% concentration at room temperature
  • Corrosiveness: Highly corrosive
• Reaction of Sodium Hydroxide with acids

  NaOH + HCl → NaCl + H2O

  2NaOH + H2SO4 → Na2SO4 + 2H2O
• Reaction of Sodium Hydroxide with Ferric Chloride

  3NaOH + FeCl3 → Fe(OH)3 + 3NaCl
• Reaction of Sodium Hydroxide with Aluminium and Zinc

  2NaOH + 2Al + 2H2O → 2NaAlO2 + 3H2

  2NaOH + Zn → Na2ZnO2 + H2