Chemical and Fuel cells Flashcards
what type of cells are used in torches, phones and cars
chemical cells
what is a battery made of
2 or more chemical cells joined together in series
what does a simple chemical cell consist of
two different metals dipping into solutions of their salts, a salt bridge to complete the circuit and allow the movement of ions
what is the overall reaction that happens in a Daniel cell
exothermic reaction
what happens when one of the reactants are used up in a cell
the reaction stops and a voltage is no longer produced
how do you increase the voltage in a cell
by using two metals with a greater difference in reactivity
what happens to the more reactive metal in a chemical cell
it loses electrons and is the negative pole
it loses mass
what happens to the less reactive metal in a chemical cell
it gains electrons and is the positive pole
it gains mass
what is the direction of electron flow in a chemical cell
more reactive metal to the less reactive metal
how can you tell from a cell diagram which cell is more reactive
the more reactive electrode loses mass and becomes smaller
why does a fuel cell not go flat like a normal battery
it produces a voltage as long as the fuel (hydrogen) and oxygen are supplied
what happens in a hydrogen-oxygen fuel cell
hydrogen and oxygen react to produce a voltage and the only product is water
what are the advantages of chemical cells
they are suitable for portable appliances
they are cheap to manufacture
what are the disadvantages of chemical cells
they do not produce a voltage when one of the reactants are used up
they may contain harmful substances
the voltage produced by these cells falls after a while
what are the advantages of hydrogen-oxygen fuel cells
they produce a voltage as long as the fuel and air are supplied
they only produce water as a product, hence no carbon dioxide is produced at the point of use
they are much quieter and need less maintenance than petrol or diesal engines
they do not need recharging
