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18 Cards in this Set
- Front
- Back
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What is the first law of thermodynamics? |
Energy must be exchanged between a chemical system and the surroundings, but the total energy remains constant |
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What are standard conditions? |
273K 1 atm 1mol dm-3 |
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Define enthalpy change of formation |
The enthalpy change when 1 mole of a compound is formed from its constituent elements in standard conditions |
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Define enthalpy change of combustion |
The enthalpy change when 1 mole of a substance is completely burnt in excess oxygen |
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What are the products of combustion? |
carbon dioxide and water |
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Define Hess's Law |
The overall enthalpy change is independent of route taken, providing the initial states of the reactants and final states of the products remain constant |
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Why are bond enthalpies average values? |
The same bond can exist in different environments |
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What does the m represent in the calorimetry equation? |
Mass of liquid |
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What does the c represent in the calorimetry equation? |
Specific heat capacity |
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Why do you have to add excess magnesium in the p.s.c experiment? |
To be able to calculate moles |
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Why is extrapolating the graph more accurate than using the highest temperature recorded? |
It gives the answer based on an immediate reaction with no heat loss to the surroundings |
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Name 4 major pollutants |
sulphur dioxide carbon dioxide carbon monoxide unburnt hydrocarbons |
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What does sulphur dioxide cause? |
acid rain |
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How is ethanol carbon neutral? |
The carbon dioxide removed from the atmosphere (photosynthesis) is equal to that given in burning |
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How are super catalysts more efficient? |
They lower the activation energy more than the conventional catalysts |
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Why are super catalysts good? |
Can run industrial processes at a lower temperature and pressure = less energy required, therefore less pollution and a lower running cost Product may also be formed faster |
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What are the advantages of recycling? |
Doesn't replete raw materials Less energy used = less pollution Rids of waste Gives people jobs |
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Why is it useful for the reaction to produce steam? |
It can be trapped and used to generate energy |
