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Heat changes in chemical reactions
Heat changes in chemical reactions
Heat changes in chemical reactions
Heat changes in chemical reactions
Heat changes in chemical reactions
Heat changes in chemical reactions
Heat changes in chemical reactions
Heat changes in chemical reactions
Heat changes in chemical reactions
Heat changes in chemical reactions
Heat changes in chemical reactions
Heat changes in chemical reactions
Heat changes in chemical reactions
Heat changes in chemical reactions
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Heat changes in chemical reactions

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  • 1. HEAT CHANGES IN CHEMICAL REACTIONS<br />
  • 2. The chemical reaction that results in heat produced is called an exothermic reaction.<br />Example- Dissolving sodium hydroxide in water.<br />
  • 3. Exothermic reaction accompanied by a rise in temperature of the surrounding.<br />
  • 4. The chemical reaction that absorbs heat from the surrounding is called an endothermic reaction.<br />Example- Dissolving ammonium chloride in water.<br />
  • 5. Endothermic reaction resulting a drop of the temperature of the surrounding.<br />
  • 6. Energy graph for an exothermic reaction<br />
  • 7. Energy graph for an endothermic reaction.<br />
  • 8. The change of energy level in a chemical reaction is denoted by the symbol <br />
  • 9. When the energy level of the product is higher than that of reactants , energy is absorbed.<br />The reaction is endothermic and is (+) ve.<br />
  • 10. When the energy level of the product is lower than the reactants, energy is released.<br />The reaction is exothermic and is (-) ve.<br />
  • 11. HEAT CHANGES IN INDUSTRIAL CHEMICAL REACTION<br />If a reaction is exothermic and reversible, heating the process to a very high temperature would decrease the yield of the products.<br />Example- Production of ammonia<br />
  • 12. HABER PROCESS<br />Production of ammonia<br />Nitrogen + Hydrogen Ammonia + Heat<br />Heat is given off. So a low temperature will give better yield.<br />But a low temperature will cause the reaction to proceed slowly.<br />A moderate temperature of 450-500 is used.<br />
  • 13. CONTACT PROCESS<br />Production of sulphuric acid.<br />Sulphur dioxide + Oxygen Sulphurtrioxide + Heat<br />Heat is given off. So a low temperature will give better yield.<br />But a low temperature will cause the reaction to proceed slowly.<br />A moderate temperature of 400-500 is normally used.<br />
  • 14. The sulphur trioxide is passed into concentrated sulphuric acid to form oleum.<br />Sulphur trioxide + Con. Sulphuric acid Oleum<br />Oleum + Water Sulphuric acid<br />

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