A reaction that transfers energy to the surroundings (the reactants had a greater store than the products)
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What are some types of exothermic reactions
Combustion, neutralisation and many oxidation reactions
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What is combustion
The burning of fuels
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Give some examples of exothermic reactions
Potassium hydroxide with hydrochloric acid (neutralisation). Sodium with water (oxidation)
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Give some examples of everyday exothermic reactions
Handwarmers (oxidation of iron in air with a salt solution catalyst). Selfheating cans of drink (exothermic reactions between chemicals in their bases)
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What is an endothermic reaction
Takes in energy from the surroundings (products have a greater energy store than the reactants)
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What type of reactions are endothermic
Thermal decomposition
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What is a reaction profile
A graph showing the energy level throughout a reaction (also called an energy level diagram)
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What are the three pieces of information you can find from a reaction profile
Overall energy change, what type of reaction it is, and the activation energy
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How do you calculate the overall energy change
Find the difference between the energy of the reactants and products
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How do you find out whether a reaction is exothermic or endothermic
If the products have more energy than the reactants its endothermic, and if its reversed its exothermic
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What is the activation energy
The minimum energy needed for the particles to react
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How do you find the activation energy
It's the difference between the highest point on the curve and where the curve starts
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What is the unit of energy
Joules or kilojoules (1000 joules in a kilojoule)
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What type of reaction is bond breaking
Endothermic, as energy is supplied
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What type of reaction is bond forming
Exothermic, as energy is released
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How do you calculate energy change in a reaction
Energy of bond breaking - energy of bond making
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What is cell (in electrical terms)
A system that contains chemicals which react and produce electricity
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What does a cell contain
Two different electrodes in contact with an electrolyte (all of which conduct electricity, and the electrolyte contains ions which react with the electrodes)
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How do you produce electricity from a cell
Attach the two electrodes with a wire, so charge can flow
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How can you measure the voltage of a cell
By attaching a volunteer to the circuit
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Other cards in this set
Card 2
Front
What is an exothermic reaction
Back
A reaction that transfers energy to the surroundings (the reactants had a greater store than the products)
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