16 - Chemical Cells & Fuel Cells Flashcards
What is a chemical cell?
A device that produces a voltage due to reactions between reactants stored inside it, until one of the reactants are used up
What are the components of a simple chemical cell?
- 2 different metals, each dipped into a solution of one of their salts
- A salt bridge
What is the purpose of a salt bridge in a chemical cell?
Allows dissolved ions to pass from one solution to the other
How does voltage get affected if the metals are further apart in the reactivity series?
The further away the metals are, the higher the voltage
What is this cell called?
Daniell cell
How would you set up a Daniell cell?
What is word & chemical reaction that happens in the Daniell cell?
What type of reaction is zinc + copper sulphate?
Exothermic
What type of cells are most modern batteries?
Dry cells - solutions are mixed w/ a powder to make a paste
In a hydrogen - oxygen fuel cell, what is used to produce a voltage?
Hydrogen & oxygen is used to produce a voltage
In a hydrogen - oxygen fuel cell, what is the product of the reaction?
Water ONLY
What are the strengths of using fuel cells?
- No burning takes place inside fuel cells
- They do not go ‘flat’ - they produce a voltage for as long as reactants are supplied
What are the weaknesses of using hydrogen - oxygen fuel cells?
- Difficult to store hydrogen
- Manufacturing processes produce Co2 as a bi-product
What are the strengths of using hydrogen - oxygen fuel cells?
- Much quieter & need less maintenance than a petrol or diesel engine
- Does not produce any greenhouse gases
Describe what is happening to the left-hand electrode
Hydrogen atoms lose electrons and form hydrogen ions
Describe what is happening to the right-hand electrode
- Electrons flow through the external circuit to the positive electrode
- Hydrogen ions pass through a membrane to the electrode where they gain electrons & react with oxygen
What is the purpose of the membrane in the electric motor?
Lets hydrogen ions out but not electrons
