AS Chemistry - Enthalpy

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Define exothermic
Heat is given out to the surroundings (the reactants lose energy)
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Define endothermic
Heat is taken in from the surroundings (the reactants gain energy)
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Define activation energy
The minimum energy required to start a reaction by the breaking of bonds
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What are the standard conditions?
pressure of 100kPa (1 atmosphere) temperature of 298K (25oC) concentration of 1.0moldm-3 (for reactions with aqueous solutions)
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Define Enthalpy Change of Combustion
The enthalpy change that takes place when 1 mole of a substance reacts completely with oxygen (all reactants and products in their standard states and under standard conditions).
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What ae the two equations to work out enthalpy change?
Q = m x c x ∆T and ∆H = q / n
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Define Enthalpy Change of Neutralisation
The enthalpy change that accompanies the neutralisation of an aqueous acid by an aqueous base to form one mole of H2O(l), under standard conditions.
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What is the equation to work out Delta Hr?
∆Hr = Σ(bond enthalpy of bonds broken) - Σ(bond enthalpy of bonds formed)
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Define Enthalpy Change of Formation
The enthalpy change that takes place when 1 mole of a compound is formed from its constituent elements (all reactants and products in their standard states and under standard conditions).
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Other cards in this set

Card 2

Front

Define endothermic

Back

Heat is taken in from the surroundings (the reactants gain energy)

Card 3

Front

Define activation energy

Back

Preview of the front of card 3

Card 4

Front

What are the standard conditions?

Back

Preview of the front of card 4

Card 5

Front

Define Enthalpy Change of Combustion

Back

Preview of the front of card 5
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