Energy Changes Flashcards
What is an exothermic reaction? - Energy
A reaction in which energy is given to the surroundings. The temperature of the surroundings will increase
Name 2 examples of exothermic reactions - Energy
Combustion reactions
Oxidation reactions
Neutralisation reactions
What is an endothermic reaction? - Energy
A reaction in which energy is taken in from the surroundings. The temperature of the surroundings decreases
Name an example of endothermic reactions - Energy
Thermal decomposition reactions
Describe an exothermic reaction profile diagram - Energy
Reactants have more energy than products, activation energy loops upwards
Describe an endothermic reaction
profile diagram - Energy
Products have more energy than the reactants, activation energy loops upwards
What is activation energy? - Energy
The minimum amount of energy that colliding particles must have for them to react
During which types of reaction are bonds broken? - Energy
Endothermic (energy taken in)
During which type of reaction are bonds made? - Energy
Exothermic (energy given out)
How do you calculate the energy change of a reaction? - Energy
Add together all reactants’ bond energies, add together all products’ bond energies.
Subtract products’ bond energies from reactants’ bond energies to find energy change
What is a chemical cell? - Energy
A store of energy which can create an electric current in a circuit
What type of cell is an alkaline cell? - Energy
A rechargeable cell
How can you produce a cell with a high voltage? - Energy
Use 2 metals with the largest difference in reactivity as electrodes to create a high voltage
What is a fuel cell? - Energy
A device which continuously produces a voltage when supplied with fuel and oxygen
What happens to the fuel in a fuel cell? - Energy
The fuel is oxidised, meaning that the reaction takes place at a lower temperature than if it was burned. Energy released as electrical energy.
What is a hydrogen-oxygen fuel cell? - Energy
A cell where hydrogen and oxygen are used as the fuel. Water is formed as the only product
What are the pros and cons of alkaline cells? - Energy
Pros - cheap to manufacture
Cons - may end up in landfill sites, expensive to recycle
What are the pros and cons of rechargeable cells? - Energy
Pros - can be recharged many times, reducing use of resources
Cons - costs a lot to manufacture/buy
What are the pros and cons of hydrogen fuel cells? - Energy
Pros - small in size, water is the only chemical product other than energy
Cons - very expensive to manufacture, need a constant supply of hydrogen (flammable)
What are alkaline cells usually used for? - Energy
Used in AA batteries to power remotes, devices
What are rechargeable cells often used for? - Energy
Used for rechargeable devices such as phones, car batteries
What are hydrogen-oxygen cells used for? - Energy
Used in spacecraft as they produce useful drinking water, as well as they have lots of access to hydrogen
