2.3.1 Enthalpy Changes

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What happen in an exothermic reaction?
energy transferred from the system to the surroundings // products have less energy
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What happens in an endothermic reaction?
energy transferred from the surroundings ti the system // products have more energy // requires input of heat energy
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What are the standard conditions of enthalpy changes?
100kPa / 289K / 1moldm^-3 concentration
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What is the enthalpy change of reaction?
enthalpy change when the number of moles of reactants as specified in the balanced equation react together
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What is the standard enthalpy change of formation?
enthalpy change when one mole of a compound is formed from its elements under standard conditions
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What is standard enthalpy change of combustion?
the enthalpy change that takes place when 1 mole of a substance reacts completely with oxygen under standard conditions
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How do you calculate enthalpy change?
Q = McT in joules
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What is mean bond enthalpy?
enthalpy change when 1 mole of bonds (gaseous covalent) are broken
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How do you calculate bond enthalpy if all substances are gases?
sum of bond energies broken - sum of bond energies made
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Why are bond enthalpies calculated with gases less accurate?
mean bond enthalpies are not exact
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what is Hess's Law?
total enthalpy change at a constant pressure for a reaction is independent of the route by which the chemical change takes place
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Card 2

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What happens in an endothermic reaction?

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energy transferred from the surroundings ti the system // products have more energy // requires input of heat energy

Card 3

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What are the standard conditions of enthalpy changes?

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Card 4

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What is the enthalpy change of reaction?

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Card 5

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What is the standard enthalpy change of formation?

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