Chemical change Flashcards
What is an exothermic reaction
A reaction in which energy is given out to its surroundings
tempurature of environment increases
What are 2 examples of an exothermic reaction
Reaction between acids and metals
Combustion of fuels
What is an endothermic reaction
A reaction in which energy is taken from its surroundings
tempurature of environment decreases
What are 2 examples of an endothermic reaction
Thermal decomposition of carbonates
Electrolysis
Is bond breaking endo or exothermic
endothermic
Is bond forming endo or exothermic
exothermic
What happens when a fuel is burned
It releases heat (exothermic reaction)
Bonds are made
When a hydrocarbon is completely combusted what is produced
Carbon dioxide and water
What is hydrogen used for as a fuel
In rocket engines and fuel cells for cars
Advantages of hydrogen as a fuel
It releases more energy per kilogram than any other fuel
It does not pollute as it only releases water upon combustion
No energy is lost in transmission
Disadvantages of hydrogen as a fuel
Expensive to produce and store
High pressure tanks are required to store hydrogen and oxygen in sufficient amount
Fuel cells become less efficient at lower tempuratures
Dangerous to store
How is Uranium-235 used as fuel
It undergoes decay and gives of heat energy which nuclear power stations harness
How is the heat energy used in nuclear power stations
It is used to heat water to steam
This is used to power turbines to produce electricity
Is nuclear fuel clean energy and why
Yes - it doesn’t produce CO2, or nitrogen oxides or sulphur
Disadvantages of nuclear power stations
Expensive to maintain
Dangerous - radioactive material can be released in an accident
