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15 Cards in this Set
- Front
- Back
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What type of reaction gives a negative enthalpy change and what type gives a positive enthalpy change? |
Negative- exothermic Positive-endothermic |
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What is activation energy? |
The minimum energy required for a reaction to take place |
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Where is activation energy shown on the enthalpy profile diagrams? |
From the initial enthalpy to the top of the curve |
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What are the standard conditions? |
Pressure- 100kPa Temperature- 25°C (298 K) Concentration- 1 mol dm-3 |
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What is the standard state? |
The physical state of a substance under standard conditions |
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What is the definition of the standard enthalpy change of reaction? |
The enthalpy change that accompanies a reaction in the molar quantities shown in a chemical equation under standard conditions, with all reactants and products in their standard states |
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The definition of the standard enthalpy change of formation? |
The enthalpy change that takes place when one mole of a compound is formed from its elements under standard conditions, with all reactants and products in their standard states |
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The definition of the standard enthalpy change of combustion |
The enthalpy change that takes place when one mole of a substance reacts completely with oxygen under standard conditions, with all reactants and products in their standard states. |
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Definition of the standard enthalpy change of neutralisation |
The energy change that accompanies the reaction of an acid by a base to form one mole of H2O under standard conditions, with all reactants and products in their standard states |
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Equation of calculating an energy change |
q=mc △T q- heat energy m- mass of surroundings c - specific heat capacity △T- temperature change of surroundings |
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Definition of average bond enthalpy |
Average enthalpy when one mole of bonds is broken |
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Definition of average bond enthalpy |
Average enthalpy when one mole of bonds is broken |
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Does a positive bond enthalpy mean a bond is being broken or being formed? |
Broken Negative bond enthalpy is when a bond is being formed |
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Definition of Le Chatiliers principle |
Equilibrium shifts to minimise any change |
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Exam tip: when calculating enthalpy change don’t but everything into the calculator at once |
Cheers |
