Energy Change
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Transcript of Energy Change
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Energy Change
14th July 2015
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What is a Reaction?
• A reaction can be physical or chemical.
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For a chemical reactions, reactants areconverted to products.
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For a physical reactions, the substance inquestion undergoes a change in state.
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What is Activation Energy?
• Chemical reactions usually require some heat
to be absorbed before it can begin. This heat
comes in the form known as activation energy.
• This heat is absorbed from the surroundings.
• Heat is a form of energy and is transferred to
atomsmolecules to change their motion.
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Activation Energy
• Why does a mixture of oxygen and nitrogen explodes only
when heated? This is because the heat acts as a source of
energy to help the reaction get started. !ost reactions cannot
occur at rtp as reactants are not energetic enough. Hence heat
provides energy to help convert less energetic particles into
more energetic ones. Activation energy is the hump that
needs to be overcome before a reaction can proceed.
• Activation energy is the minimum amount of energy that
reactant particles must have in order for a chemical reaction
to occur. "t is represented by the symbol #a.
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What is a Chemical Reaction?
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What happens during a Chemical Reaction?
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Chemical Reaction = Endothermic + Exothermic
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Chemical Reaction = Endothermic + Exothermic
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Endothermic or
Exothermic?
• Hence a chemical reaction is eitherexothermic or endothermic, eventhough bond breaking hich is an
endothermic !rocess and bondbreaking hich is an exothermic!rocess occurs simultaneously during
a chemical reaction"
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What is Enthalpy?
