Topic 5 Flashcards
(18 cards)
What is a exothermic reaction and give an example of one?
An exothermic reaction is one which transfers energy to its surroundings so the temperature of the surrounding increases. Examples are; Combustion, neutralisation and oxidation reactions. An everyday example of one is a sports injury pack.
What is an endothermic reaction and give an example of one?
A reaction that takes in energy from the surrounding so the temperature of the surroundings decreases. Examples are; thermal decomposition. Everyday examples ae sports injury packs.
Is this reaction profile exothermic or endothermic?
It is exothermic.
What is activation energy?
Activation energy is the minimum amount of energy that particles must have to react.
What reaction profile is this?
Endothermic.
In exothermic reactions is the energy released by forming bonds greater or less than the energy used to break them and what is it in endothermic?
The energy released when forming new bonds is greater.
Is endothermic making bonds or breaking bonds?
Endothermic is breaking bonds.
Is exothermic breaking bonds or forming bonds?
Forming bonds.
What is a cell in chemistry?
A cell contains chemicals that react to produce electricity.
How can you make a simple cell?
Connect two different metals in contact with an electrolyte.
What does the voltage produced by the cell depend on?
It depends on the type of electrode.
And what type of electrolyte we have.
What is the difference between a non rechargeable cell and a rechargeable cell and give an example of each.
In a non-rechargeable cell when one of the reactants is used up the chemical reactions stop. An example is an alkaline battery.
A rechargeable battery is where a chemical reaction is reversible when an external electric current is applied. An example is mobile phone batteries.
What is a fuel cell?
Are cells supplied with an external source of fuel for example hydrogen and oxygen.
How do fuel cells work?
The fuel cell is oxidised electrochemically within the fuel cell to produce a potential difference.
How does a hydrogen fuel cell work and what is the chemical formula?
Uses hydrogen and oxygen as fuels.
What are the half equations that take place in the cathode of a hydrogen fuel cell?
What are the half equations that take place in the anode of a hydrogen fuel cell?
What are the advantages and disadvantages of a hydrogen fuel cell?
