Studied by 6 people
electric circuit
The flow of the electrons, through the ________, from the cathode to the anode generates a current.
combustion process
A(n) ________ requires the presence of a fuel, oxygen and heat.
Heat energy
________ is absorbed from the surroundings.
exothermic reaction
Burning fuels to form oxides is a(n) ________.
Fuel
________: substance that can be used as a source of energy.
overall heat energy value
If ________ is positive, reaction is endothermic.
Energy level diagrams
________ show the relative energies of the reactant and product.
Heat energy
________ is released into the surroundings.
overall heat energy value
If ________ is negative, reaction is exothermic.
Energetics of a Reaction
Chemical reactions involve a transfer of energy between the system (the chemical reaction) and its surroundings
Activation energy
the minimum energy required for the reaction to take place
Fuel
substance that can be used as a source of energy
The product is water
2H2 + O2 → 2H2 O
4H+ + O2 + 4e
→ 2H2 O
A good fuel is:
Cheap
Available in large quantities
Liquid at room temperature
Have high efficiency (produce a large amount of energy)
Does not produce polluting gases
Advantages of Hydrogen fuel cells
Releases a lot of energy
Does not produce pollutants
Renewable and abundant
Disadvantages of hydrogen fuel cells
Difficult to transport as it is a gas at room temperature
Forms explosive mixture with air when stored under pressure
Is expensive to produce (requires a lot of energy)
exothermic reaction
Heat energy is released into the surroundings
Bond making reactions
Surrounding temperature increases
endothermic reaction
Heat energy is absorbed from the surroundings
Bond breaking reactions
Surrounding temperature decreases
Product(s) of hydrogen fuel cell
Water (ONLY)
Note 
Flashcard (24)