Fuel and Chemical Cells Flashcards
(22 cards)
What is a chemical cell?
A source of electrical energy with two electrodes made from different metals immersed in an electrolyte
What is the simplest design of a chemical cell?
Two electrodes connected to an external voltmeter by wire, creating a complete circuit
Which metals are commonly used in a simple chemical cell?
Zinc and copper
Why does zinc have a negative charge in a chemical cell?
Zinc is the more reactive metal and readily releases electrons
What causes a voltage to be produced in a chemical cell?
The difference in the ability of the electrodes to release electrons
What happens to the electrodes over time in a battery?
They degrade as the reactions that occur are irreversible
What is the difference between a cell and a battery?
A battery connects two or more cells in series to give a larger overall voltage
What occurs when one of the reactants in a cell is used up?
The battery dies or goes flat
What is a non-rechargeable battery?
A battery where the products cannot be reverted back into reactants
How do rechargeable batteries work?
The reactions are reversed by connecting the cells to an external electrical supply
What is a hydrogen fuel cell?
An electrochemical cell where fuel donates electrons at one electrode and oxygen gains electrons at the other
What happens to fuel in a hydrogen fuel cell?
It becomes oxidised, setting up a potential difference or voltage within the cell
What is produced in a hydrogen-oxygen fuel cell?
Energy and water
What is one advantage of hydrogen fuel cells?
They do not produce any pollution
What is another advantage of hydrogen fuel cells?
They produce more energy per kilogram than petrol or diesel
What is a disadvantage of hydrogen fuel cells?
Materials used in producing fuel cells are expensive
What is another disadvantage of hydrogen fuel cells?
High pressure tanks are needed to store hydrogen and oxygen
What occurs at the anode in a hydrogen fuel cell?
Hydrogen is oxidised
What occurs at the cathode in a hydrogen fuel cell?
Oxygen is reduced
What is the overall reaction in a hydrogen fuel cell?
2H2 + O2 → 2H2O
What is the function of the electrons in a hydrogen fuel cell?
They move around the external circuit to drive an electric motor
Fill in the blank: A cell consists of an electrolyte which is usually _______ and porous carbon electrodes coated with a catalyst.
phosphoric acid
