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

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Brønsted-Lowry acids and bases

• Definition of acid: substance that donates protons

• Definition of base: substance that accepts protons

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

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• conjugate acid acid-base pair:

  • species that differ by a single proton​

  • ​example​:

Amphiprotic species

• Definition: species that may donate or accept protons

• example:

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Note: do not confuse with amphoteric

Proprieties of acids​

• sour taste

• pH<7.0

• litmus is red

• phenolphthalein is colourless

• methyl orange is red

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Proprieties of bases

• bitter taste 

• ph>7.0

• litmus is blue

• phenolphthalein is pink

• methyl orange is yellow

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Reactions

• 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

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

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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

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Acid rain

• Due to         in the atmosphere

• Reaction pathways:

• pH< 5.6 (normal pH of rain)

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Major pollutants (both cause acid rain)

• Nitrogen Oxides

  • Reaction pathways:​

• Sulphur dioxide

  • Reaction pathways:​

​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 ​

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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​​