Rates of Reaction and Energetics

Endothermic
1. Bring in heat from surroundings
  1. Measure: increase in temperature
2. Make bonds
3. Endothermic is posotive
4. Reactions that convert heat energy to chemical are called Endothermic reactions
Exothermic
1. gives out heat from the surroundings
  1. Measure: drop in temperature
2. Break bonds
3. Endothermic is negative
4. Combustion is an example of exothermic reaction
Breaking and making bonds needs/uses energy
Delta H= Reactants-Products
Bond Energies
1. The energy released when a bond is formed or absorbed when it is broken.
Energy released= m x c x delta T
Energy per gram= Energy released/mass of fuel burned
Reactions occur when the rectant particles collide with each other
1. The more collisions between reactants is a given time, the faster the rate
2. Reaction rates can't be determined by the amount of product per second
3. More energy=more likely to overcome activation energy.
4. Effect of surface area=the larger the surface area the more chance that the particles will collide, so the rate of reaction will increases.
5. Soon all surface will have been reacted with so the surface area soon becomes the limiting factor.
  1. This will be indicated by a line flattening on a graph
6. Trend-as the surface area increases so does the reaction rate
7. catalysts increases the rate of reaction
  1. They bring the particles together in the right allignment
  2. A substance which increases the rate of reaction without affecting itself
  3. Neutralise-Nitrous oxide Carbon monoxide and unreacted hydrocarbons
as the temperature increases, the number of collisions between particles also increases. The collisions will be more energetic , so overall the rate of reaction increases.

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Rates of Reaction and Energetics

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