Energy Changes Flashcards
What are everyday uses that use endothermic reactions?
Sports injury packs as they cool fast
What are everyday examples of exothermic reactions?
Hand warmers
Self heating cans of hot chocolate
How can you measure the energy transfer in the reaction?
What do you do to try make it more accurate?
Measure the temperature from the reagents and then from the products
Do it in a polystyrene seal to trap heat.
Where can electricity be created with chemical reactions?
Electricity can be generated with chemical reactions inside a cell
What causes the variation of voltage in a cell?
Different metals will react differently with the same electrolyte
Why are some batteries non-rechargeable?
The reactants in the cell gets used up as the reaction is irreversible.
How are some batteries rechargeable?
How can they get their charge back?
They’re reversible so the reactants can get reused
They are recharged using a different source of electricity
What us used to produce fuel cells?
Oxygen and fuel to produce electrical energy
What happens when the fuel enters the cell?
It becomes oxidised and can carry a potential difference in the cell.
What is a fuel cell people are wanting in cars?
What is the reaction that takes place?
Hydrogen + water –> Water + energy
What are negatives about normal electrical power for cars?
They will eventually run out and need to be replaced after constant recharges
How are hydrogen-oxygen cells produced?
The solution is usually potassium hydroxide
The oxygen ions go to the cathode and hydrogen goes to the anode
The oxygen gains electrons from the cathode.
When the H+ ion is made, it travels to the Oxygen and reacts with oxygen and forms water, this is reduction.
In FUEL CELLS, what is the negative and positive cathode?
The anode is the negative electrode and the cathode is the positive electrode
What atom goes to the anode?
Hydrogen
What atom goes to the cathode?
Oxygen
