Pre combustion methods

  • physical cleaning

  • mineral beneficiation

    • example: crushing and then floating the coal before burning to remoce sulphur 

  • Removal of up to 80%-90% of impurities ​

Post combustion methods

  • Removal of gases before releasing in the atmosphere

    • example: car catalysts​

Effects of acid rain

  • Damage in limestone or marble buildings due to exposure to acid rain, as shown in the following reaction​​

Arrhenius's theory of acid and base

  • Definition of acid: substance that when ionized in water produces 

  • Definition of base: substance that when ionized in water produces

Brønsted-Lowry acids and bases

  • Definition of acid: substance that donates protons

  • Definition of base: substance that accepts protons

Note: do not confuse with Lewis acid and bases!!!

  • conjugate acid acid-base pair:

    • species that differ by a single proton​

    • ​example​:

Amphiprotic species

  • Definition: species that may donate or accept protons

  • example:

Note: do not confuse with amphoteric

Proprieties of acids

  • sour taste

  • pH<7.0

  • litmus is red

  • phenolphthalein is colourless

  • methyl orange is red

Proprieties of bases

  • bitter taste 

  • ph>7.0

  • litmus is blue

  • phenolphthalein is pink

  • methyl orange is yellow


  • acid + metal --> salt + hydrogen

  • Example:

  • acid + base --> salt + water

  • Example:

  • acid + metal carbonate/ hydrogen carbonate --> salt + carbon dioxide 

  • Example:

Used to measure the concentration of hydrogen ions H+ in a solution

Ionization of Water

Strong acid

  • An effective proton donor, that is assumed to completely dissociate in water.

  • There is no equilibrium.

  • Weak conjugate base.

  • Example:

Weak acid

  • A poor proton donor, dissociates only partially in water.

  • There is equilibrium.

  • Example:

Strong base

  • An effective proton acceptor, that is assumed to completely dissociate in water.

  • There is no equilibrium.

  • Weak conjugate acid.

  • Example:

Weak base

  • A poor proton acceptor, dissociate only partially in water.

  • There is equilibrium.

  • Example:

Conductivity: is proportional to the concentration of ions in the solution.

  • Strong acids and bases are good conductors

  • Weak acids and bases are bad conductors

Energy changes in neutralization

  • The weaker the acid the lower enthalpy change of neutralization

Acid deposition

  • Formation of pollutants that are deposited on Earth's surface, from acids

Acid rain

  • Due to         in the atmosphere

  • Reaction pathways:

  • pH< 5.6 (normal pH of rain)

Major pollutants (both cause acid rain)

  • Nitrogen Oxides

    • Reaction pathways:

  • Sulphur dioxide

    • Reaction pathways:

Topic 8: Acids and Bases

8.1 Theories of Acids and Bases

8.2 Properties of Acids and Bases

8.3 The pH Scale

8.4 Strong and Weak Acids and Bases

8.5 Acid Deposition and are student initiatives to provide free material to help international students prepare themselves for the IB exams.

Contact: Fernando Alonso Bilfinger |