39 Questions
What is the purpose of connecting the electrode to another half-cell of known potential when measuring potential difference?
To establish a reference point for potential measurement
In a cell diagram, how is the hydrogen electrode represented?
Pt |H2 (g) | H+ (aq)
Why are standard conditions necessary for a reference electrode like the standard hydrogen electrode?
To maintain the same redox equilibrium position for accurate potential measurement
What happens to the potential of an electrode if the concentration of metal ions in solution increases?
The potential becomes more positive
Which component is NOT required for a standard hydrogen electrode to function as a reference electrode?
Metal electrode such as Fe
What is the purpose of using a platinum wire coated in finely divided platinum in electrode potential measurements?
To act as a catalyst because it is porous and can absorb hydrogen gas
In the context of electrode potential measurements, what does SHE stand for?
Standard Hydrogen Electrode
What are the standard conditions required for electrode potential measurements?
All ion solutions at 1.00 mol dm-3, gases at 100 kPa pressure, and no current flowing
Which electrode system is connected to the hydrogen electrode system to measure standard electrode potential?
Platinum electrode with Fe2+/Fe3+ ions
How are standard electrode potentials typically quoted in data books?
With the more reduced form on the left side of the equation
What does the potential difference (E) of +1.1V for the given cell indicate?
The zinc half-cell has more tendency to oxidize to Zn2+ and release electrons compared to the copper half-cell.
Why is a high resistance voltmeter used when measuring potential difference in an electrochemical cell?
To measure the maximum possible potential difference (E).
What is the purpose of a salt bridge in an electrochemical cell?
To balance the charge in the two half-cells and complete the circuit.
Which electrode in the given cell is considered the negative terminal?
Zinc electrode
What happens when a very high resistance voltmeter is used during potential difference measurement in an electrochemical cell?
The maximum possible potential difference (E) can be measured accurately.
What type of electrode must be used in a system that does not include a metal that can act as an electrode?
Platinum electrode
In the cell diagram, how are H+ ions and H2O treated when the system contains multiple species?
They can be left out
What is used to separate different physical states in a half equation?
Vertical line ( | )
In the context of electrode potential measurement, why is it not possible to measure the absolute potential of a half electrode on its own?
Lack of reference point
What is the purpose of the salt bridge in a cell diagram?
To establish ionic connection between half cells
What is usually used to make a salt bridge in an electrochemical cell?
Piece of filter paper soaked in a salt solution
Why is potassium chloride not suitable for copper systems in a salt bridge?
It forms complexes with chloride ions
Why is a wire not used as a salt bridge in an electrochemical cell?
It sets up its own electrode system
In an electrochemical cell, what happens when the voltmeter is replaced with a bulb or if the circuit is short-circuited?
The reactions occur separately at each electrode
Which electrode always undergoes reduction in an electrochemical cell?
The most positive electrode
Which type of cells are non-rechargeable due to having non-reversible reactions?
Primary cells
What is the overall reaction for the primary Lithium–manganese dioxide cell?
Li+aq + MnO2 (s) +e- → LiMnO2(s)
In a lead-acid cell, what is the half-reaction that occurs during discharge?
PbSO4 + 2e- → Pb + SO42-
What is the standard electrode potential for the half-reaction: Zn2+(aq) + 2e- → Zn(s)?
-0.76 V
What components are present in the conventional cell diagram for the Lithium-manganese dioxide cell?
Li (s)| Li+aq | | Li+aq | MnO2 (s), LiMnO2(s) | Pt (s)
What is the equation used to calculate the EMF of a cell?
Ecell = Erhs - Elhs
Which half cell has a standard electrode potential value of -2.37V?
Mg2+ (aq) | Mg(s)
Which direction does the more negative half cell in a redox reaction tend to proceed?
Oxidize (go backwards)
What is the electrode potential for the half equation: Fe2+(aq) + 2e- → Fe(s)?
-0.44V
Which electrode will reduce and go from left to right in a redox reaction?
Fe(s)
In a spontaneous change, what is the value of Ecell typically?
Positive
Which equation would you use to calculate the Ecell for a spontaneous change?
Ecell = Ered – Eox
What happens in the reaction: Zn2+(aq) + 2e- → Zn(s)?
Reduction
What is the standard electrode potential for Cu2+ (aq) | Cu (s)?
+0.34V
Learn about the role of a salt bridge in electrochemical cells, why specific salts are chosen, and why wires are not used. Discover what happens when current flows in the presence of a salt bridge.
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