C7 energy changes Flashcards
What is the reaction of methane with oxygen
CH4(g) + 2O2(g) = CO2(g) + 2H2O(l)
What is complete combustion
Where all of the carbon in a reaction forms carbon dioxide
In a caned hot coffee what is the reaction to make it hot
CaO + H2O = Ca(OH)2
What is the correlation between the reactivity of the metal and the amount of energy change
The bigger the gap between metals on the reactivity series the larger the energy change
How do you calculate energy transferred
Energy = Mass of water * specific heat capacity of water * change in time (E = MC change in t)
What is the specific heat capacity of water
4.2
If the overall process is endothermic what is the overall energy change
Positive
If the overall process is exothermic what is the overall energy change
Negative
What is a fuel cell
A type of electrochemical cell most common is hydrogen oxygen fuel cell
How do you know something is a primary cell
It cannot be recharged
What happens to the fuel as it enters the cell
It becomes oxidised
What always happens at the anode
Oxidation
What always happens at the cathode
Reduction
What are the pros of fuel cells
- only require oxygen and hydrogen
-do not produce any As waste
-they last longer than batteries
-less polluting when disposing them
What are the cons of fuel cells
-hydrogen is a gas
-requires more space to store than fossil fuel batteries
-explosive when mixed with air
-storage is dangerous
-requires energy to be produced (fossil fuels)
