electrode potentials
No description yet. This curated deck is ready for daily study.
Card preview (24)
Which change to a hydrogen electrode has no effect on the electrode potential?
surface area of the platinum electrode
In a lithium cell, a lithium cobalt oxide electrode and a lithium electrode are used. Give the equation for the reaction that occurs at the positive electrode
Li++ CoO2 + e- → Li+(CoO2)-
State why lithium cells can be recharged
The electrode reactions can be reversed
Explain the function of the salt bridge.
the ions in the ionic substance in the salt bridge move through the salt bridge to complete the circuit
Identify an ionic compound that could be used in the salt bridge.
potassium nitrate
State why a fuel cell does not need to be electrically recharged.
Reactants supplied continuously
Suggest one advantage of using methanol, rather than hydrogen, in a fuel cell for use in cars
Methanol (is liquid so) can be stored easily
Suggest the function of the porous separator
allows ions to move
Suggest why the EMF values of the acidic and alkaline hydrogen–oxygen fuel cells are the same
same overall reaction
Suggest the major advantage of using the fuel cell
A fuel cell converts more of the available energy from combustion of hydrogen into kinetic energy of the car
The aluminium used as the electrode is rubbed with sandpaper prior to use. Suggest the reason for this.
To remove the oxide layer on the aluminium
With reference to electrons, give the meaning of the term reducing agent
electron donor
Suggest why the recharging of a lithium cell may lead to release of carbon dioxide into the atmosphere.
Electricity for recharging the cell may come from power stations burning (fossil) fuel
Deduce half-equations for the electrode reactions in a hydrogen–oxygen fuel cell.
H2 + 2OH- → 2H2O + 2e- O2 + 4e- + 2H2O → 4OH-
Explain why a fuel cell does not need to be recharged
hydrogen supplied continuously
To provide energy for a vehicle, hydrogen can be used either in a fuel cell or in an internal combustion engine. Suggest the main advantage of using hydrogen in a fuel cell rather than in an internal combustion engine.
less energy wasted
Identify one major hazard associated with the use of a hydrogen–oxygen fuel cell in a vehicle
hydrogen is flammable
Suggest one reason why many waste disposal centres contain a separate section for cells and batteries.
Prevent pollution of the environment by toxic recycling of valuable component
oxidising agent.
electron acceptor
State the conditions necessary when measuring ions
pressure at 100Kpa, conc of ions at 1moldm-3, temperature at 298K, zero current
State one essential requirement of the soluble ionic compound used to make the salt bridge
must not react with the electrolyte
Suggest two reasons why the concentration of chlorine in the vase water decreases with time.
to kill bacteria chlorine evaporated
Suggest why this sampling technique has no effect on the rate at which the concentration of chlorine in the vase water decreases
the concentration of the remaining solution is unchanged.
reducing agent
electron donor