Chemistry C3.3
- Created by: Will Pound
- Created on: 09-03-14 14:47
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- Chemistry C3.3
- Comparing the energy released by fuels
- When fuels and food react with oxygen, energy is released in an exothermic reaction
- A calorimeter can be used to compare the energy released by different fuels or food in a school lab
- Energy transfers in solutions
- Can calculate the energy change for reactions in solution by measuring the temperature change
- Q=mc?T
- Q= amount of energy transferred to the water
- M= mass of water
- C= specific heat capacity of water
- ?T= temperature change
- Q=mc?T
- Neutralisation and displacement reactions are both examples of reactions that we can use this technique for
- Can calculate the energy change for reactions in solution by measuring the temperature change
- Energy level diagrams
- We can show the relative difference in the energy of reactants and products on energy level diagrams
- Catalysts provide a pathway with a lower activation energy so the rate of reaction increases
- Bond breaking is endothermic
- Bond making is exothermic
- Calculations using bond energies
- In an exothermic reaction, the energy released when new bonds are formed is greater than the energy absorbed when bonds are broken
- In an endothermic reaction, the energy released when new bonds are formed is less than the energy absorbed when bonds are broken
- We can calculate the overall energy change in a chemical reaction using bond energies
- Fuel issues
- Much of the world relies on fossil fuels
- Fossil fuels are non renewable and cause pollution
- Alternative fuels need to be found soon
- Hydrogen is one alternative
- It can be burned in combustion engines or used in fuel cells to power vehicles
- Comparing the energy released by fuels
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