Redox theory
To balance complex redox equations, which atoms should be balanced first?
All atoms other than oxygen and hydrogen
cathode
What is a secondary cell?
What is the energy conversion that occurs in a fuel cell?
chemical to electrical
Are the reactions that occur in electrolytic cells spontaneous or non-spontaneous?
non-spontaneous
Where on the electrochemical series would you find the strongest oxidant?
top left hand corner
What is the polarity of the anode in a galvanic cell?
negative
When a secondary cell is recharging, which electrode is connected to the negative terminal of the power supply?
Cathode
The names of the four Teenage Mutant Ninja Turtles and their corresponding colours
Leonardo (blue) , Raphael (red), Michaelangelo (orange), Donatello (purlple)
What is the main advantage in using molten electrolytes rather than aqueous electrolytes in electrolytic cells?
Water is not present, therefore cannot react preferentially to desired reaction.
What is the oxidation number of S in H2SO4?
+6
Explain the function of a salt bridge
provides negative and positive charged ions that can migrate into half cells to balance the charge. Without a salt bridge, a galvanic cell will cease to operate.
What energy conversion is occurring when a secondary cell is discharging?
chemical to electrical
Hydrogen fuel cells can be used to power cars. What disadvantages are there in the use of hydrogen as a fuel?
Safety and cost of storage and transport (explosive, very light gas must be pressurised or liquefied)
Are the half-reactions in electrolytic cells separated or contained within the one vessel? Explain why
Contained within the one vessel. Ions need to be able to transfer from anode to cathode
Name the four memebrs of the Fireman Sam staff act and their instruments.
Juddy (drums), Mr Clark (guitar), Mr Johnstone (vocals and bells) and Harry (guitar)
How is the potential voltage of a galvanic cell calculated?
cell potential difference = E0 of half-cell containing oxidant - E0 of half-cell containing reductant
Josh Robertson has been in the winning act this many times.
Three
Why are porous electrodes used in fuel cells?
Increase surface area to maximise rate of reaction
Why must the products of electrolytic cells be kept separate?
They will spontaneously react
Explain the term 'conjugate redox pair'
An oxidant (reactant/product) and reductant (reactant/product) that is formed when the oxidant gains electrons or the reductant loses electrons. The conjugate redox pair differ in number of electrons. They are paired to show where electrons are transferred to and from.
Explain how standard electrode potentials (Eo values) are obtained.
By combining half-cells with the standard hydrogen half-cell.
Suggest three factors that reduce the performance of secondary cells over time
loss of active materials (become detached from electrodes or undergo side reactions)
conversion of small crystals of active material to larger crystals which increases resistance
impurities in cell that can cause side reactions
decrease in contact of electrolyte with electrodes because of leakage/reactions
corrosion or failure of internal components
Explain the function of the electrolyte in a fuel cell
Allows the transfer of ions from one electrode to another
This act won the Talent Quest last night and the song was...
Us Again Pool House