| Method |
Precise Learning Objective |
Linked |
Question / Activity
(Designed for maximum working out) |
Stepping Stones |
Pitstop Check
(Thinking Map) |
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Chemical reactions can occur only when reacting particles collide with each other and with sufficient energy. |
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Why do some collisions between reactant particles not result in a product forming? Plan Required Practical for Energy Changes |
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The minimum amount of energy that particles must have to react is called the activation energy. |
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What does the term activation energy mean? |
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Reaction profiles can be used to show the relative energies of reactants and products, the activation energy and the overall energy change of a reaction. |
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What information can be shown in a reaction profile? |
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Students should be able to draw simple reaction profiles (energy level diagrams) for exothermic and endothermic reactions showing the relative energies of reactants and products, the activation energy and the overall energy change, with a curved line to show the energy as the reaction proceeds |
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What would the simple reaction profile for an exothermic reaction look like? |
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Students should be able to use reaction profiles to identify reactions as exothermic or endothermic |
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What would the simple reaction profile for an endothermic reaction look like? |
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Students should be able to explain that the activation energy is the energy needed for a reaction to occur. |
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What information does the activation energy provide? |
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During a chemical reaction energy must be supplied to break bonds in the reactants
and energy is released when bonds in the products are formed. |
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What energy transfers occur during breaking bonds of reactants and forming new bonds of products? |
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The energy needed to break bonds and the energy released when bonds are formed can be calculated from bond energies. |
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What information can bond energies provide? |
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The difference between the sum of the energy needed to break bonds in the reactants and the sum of the energy released when bonds in the products are formed is the overall energy change of the reaction. |
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How is the overall energy change of a reaction calculated? |
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In an exothermic reaction, the energy released from forming new bonds is greater than the energy needed to break existing bonds. |
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What happens in an exothermic reaction in terms of energy, bond making and bond breaking? |
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In an endothermic reaction, the energy needed to break existing bonds is greater than the energy released from forming new bonds. |
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What happens in an endothermic reaction in terms of energy, bond making and bond breaking? |
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Students should be able to calculate the energy transferred in chemical reactions using bond energies supplied. |
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What is the energy transferred in the following chemical reaction: hydrogen bromide decomposing to form hydrogen and bromine?
2 ? (H?Br) ? H?H Br?Br
The bond energies relevant to this reaction are shown below:
H?Br 366 kJ/mol
H?H 436 kJ/mol
Br?Br 193kJ/mol |
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