3.1 Redox and standard electrode potential Flashcards
What is the negative electrode called?
Anode
What is the positive electrode called?
Cathode
In Zn –> Zn2+ + 2e- and Cu –> Cu2+ + 2e- what way do the electrons flow and why?
From Zn to Cu as zinc has a higher density of electrons
What are the functions of a salt bridge?
complete the circuit
Balance charge
allows ions to move
What do arrows on the wire represent?
Current flowing from positive to negative
What do arrows next to the wire represent?
e- flow from negative to positive
What is the definition of E0?
The voltage of a half cell when measured against the standard hydrogen electrode under standard conditions
What is the half equation for
Zn2+ + 2e- —> Zn E0=-0.76
Cu2+ + 2e- —> Cu E0=+0.34
Zn + Cu2+ —> Cu + Zn2+
What is the definition of the standard hydrogen electrode?
The half cell all other half cells are measured against under standard conditions that are 298k, 1 atm, 1moldm-3 and 0.00V
What is the standard hydrogen electrode equation?
2H+ + 2e- —> H2
What is the electrode made from in the standard hydrogen electrode? Why?
Platinum as its inert
What is required for the standard hydrogen electrode?
Hydrochloric acid
Hydrogen gas
Platinum electrode
What is emf and how is it measured?
electromotive force
high resistance voltmeter
Which electrode favours reduction?
Positive
When are batteries rechargeable? how?
When the reaction is reversible
by adding a power source with a larger emf the electrons will be forced to revert backwards and reset
What makes up a fuel cell?
two half-cells connected by a semi-permeable membrane
aqueous solution of sodium hydroxide
What is the products of an oxygen-hydrogen fuel cell?
Water
What are the advantages of an oxygen-hydrogen fuel cell?
Only water as a by product
more efficient than combustion cell
What are the disadvantages of an oxygen-hydrogen fuel cell?
Obtaining hydrogen gives of CO2
H2 is highly flammable as a gas and storing it was a liquid or solid is expensive
People will no buy hydrogen powered vehicles (danger and cost)
Fuel cells give off toxins in their manafactuing
Fuel cells have limited life span
What is the trend of oxidising agents in the electrochemical series?
Increase in strength down table (increase as more positive)
What is the trend of reducing agents in the electrochemical series?
Decrease in strength down the table (decrease as more positive)
Does the oxidiser or the reducer displace?
The oxidiser
