Energy Changes

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  • Created by: leo1223
  • Created on: 13-05-18 19:58
What is meant by an exothermic reaction?
An exothermic reaction transfers heat energy from the chemicals to its surroundings and is followed by a temperature increases
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What is meant by an endothermic reaction?
An endothermic reaction transfers heat energy from the surroundings to the chemicals and is followed by a temperature decrease
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What is meant by activation energy?
Activation energy is the minimum amount of energy that particles must have for a reaction to take place
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What happens to the energy level of the products in an exothermic reaction?
In an exothermic reaction, heat is given out to the surroundings therefore the products have less energy than the reactants
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What happens to the energy level of the products in an endothermic reaction?
In an endothermic reaction, heat is taken in by the surroundings therefore the products have more energy than the reactants
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How do catalysts affect the activation energy?
Catalysts lower the activation energy for a reaction, this increases the rate of reaction
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What happens to the bonds in a chemical reactions?
In a chemical reaction, bonds are broken in the reactants and new bonds are made to form the products
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Breaking bonds is a ... process?
Endothermic process
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Making bonds is a ... process?
Exothermic process
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If more energy is required to break bonds than is released when bonds are formed, what type of reaction is it?
Endothermic
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If more energy is released when bonds are formed than is needed to make bonds, what type of reaction is it?
Exothermic
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How can the amount of energy produced by a chemical reaction in soultion be measured?
The amount of energy produced in a chemical reaction in solution can be measured by mixing reactants in an insulated container, this allows temperature change to be measured before energy is lost to the surroundings
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How is a simple cell made?
A simple cell can be made by placing two different metals into a beaker containing an electrolyte
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What is meant by a hydrogen fuel cell?
A hydrogen fuel cell is a very efficient way of producing electricity as it chemically combines hydrogen and oxygen to form water and produce electrical energy
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What happens in a hydrogen fuel cell?
In a hydrogen fuel cell; Hydrogen and oxygen are supplied to the fuel cell, the fuel is oxidised to produce a potential difference, overall the hydrogen is oxidised to form water
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In a hydrogen fuel cell what is added at the cathode?
At the cathode, oxygen is added
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In a hydrogen fuel cell what is added at the anode?
At the anode, hydrogen is added
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What happens at the anode in a hydrogen fuel cell?
Once the hydrogen molecules are released at the anode, hydrogen molecules lose electrons to form hydrogen ions
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What happens at the cathode in a hydrogen fuel cell?
Once the oxygen molecules are released at the cathode, the hydrogen ions formed at the anode travel through the electrolyte to the cathode, at the cathode the hydrogen ions react with the oxygen molecules to form water
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Name 3 advantages of hydrogen fuel cells?
Hydrogen fuel cells produce water which is a non-polluting substance, there are lightweight and small, they have no moving parts so they are unlikely to break down
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Name 3 disadvantages of hydrogen fuel cells?
Hydrogen as a fuel is expensive, hydrogen is extremely flammable, storage issues with hydrogen as it is a gas
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Other cards in this set

Card 2

Front

What is meant by an endothermic reaction?

Back

An endothermic reaction transfers heat energy from the surroundings to the chemicals and is followed by a temperature decrease

Card 3

Front

What is meant by activation energy?

Back

Preview of the front of card 3

Card 4

Front

What happens to the energy level of the products in an exothermic reaction?

Back

Preview of the front of card 4

Card 5

Front

What happens to the energy level of the products in an endothermic reaction?

Back

Preview of the front of card 5
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