+ Reaction that takes in energy from surroundings. + Surroundings get cooler
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What is an exothermic reaction?
+Reaction that transfers energy to surroundings (remember Exits). +Temp of surroundings increases
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Give example of an endothermic
+ Electrolysis
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Give example of exothermic
+Burning
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What is a reversible rxn?
A rxn where products can react to produce original reactants
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What is meant by an equilibrium?
Reactants and products will reach a certain balance and stay there
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What is the overall effect of reversible reactions, why?
None, they cancel each other out.
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What do you use to calculate energy change ?
Break - (minus) Make
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What happens when adding a catalyst to a reversible reaction?
Reaches equilibrium quicker
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When calculating energy change, does an endothermic have a negative value or positive?
Negative
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Why do endothermics have a negative value?
Products have more energy than reactants.
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When calculating energy change, does an exothermic have a negative value or positive?
Positive
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Why do exothermics have a negative value?
Products have less energy than reactants.
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Now, In 2017, what do we use for fuel for vehicles?
Fossil fuels
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What are the disadvantages of fossil fuels?
+ Non renewable +Co2 release (global warming)
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What gas causes global warming?
Co2
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What is the alternative fuel to fossil fuels?
Hydrogen (fuel cell)
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Name a property of hydrogen
Flammable
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How do we get hydrogen?
Electrolysis of water
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What is electrolysis?
Splitting using energy
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Advantages of burning hydrogen for fuel
+ Clean burning- Only waste is water + Renewable
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h2 + o2 -> ??
2h2o
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Disadvantages of burning hydrogen as a fuel
+ Explosive + To produce hydrogen we need fossil fuels, for electricity for water electrolysis
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What is an alternative to how we make electricity?
Hydrogen
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In a cell hydrogen is what...
Oxidised
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What is oxidation ?
Loosing electrons
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How can this power vehicles?
Electrons flow and create an electrical current. This powers vehicles
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Advantages of using hydrogen for electricity
+ Coverts more of the available energy
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Disadvantages of using hydrogen for electricity
+ Needs a constant supply of hydrogen, electricity is need to generate hydrogen
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What do catalysts do?
Speed up a chemical reaction, by providing another route with lower activation energy
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Catalysts lower what energy?
Activation
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What is the calculation for energy change?
Q= mc▲T
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In Q= mc▲T, what is the m?
mass
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In Q= mc▲T, what is the C?
Specific heat capacity
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In Q= mc▲T, what is the ▲T ?
Change in temp
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In Q= mc▲T, what is the q?
heat energy
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What is the activation energy?
+ Minimum energy need for reaction + For collisions to be successful the particles involve must possess enough energy to break bonds (this is activation energy)
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Other cards in this set
Card 2
Front
What is an exothermic reaction?
Back
+Reaction that transfers energy to surroundings (remember Exits). +Temp of surroundings increases
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