Year 12 Chemistry Chapter 5

Lithium-ion rechargeable batteries are used in mobile phones. Environmental conditions can affect the number of charge cycles for a lithium-ion battery until the end of its useful life. Which of the following environmental conditions would be expected to result in the largest number of charge cycles for a lithium-ion battery?

• Minimum

  temperature (°C) -8

  Maximum

  temperature (°C) 11

• Minimum

  temperature (°C) 9

  Maximum

  temperature (°C) 21

• Minimum

  temperature (°C) 18

  Maximum

  temperature (°C) 37

• Minimum

  temperature (°C) 28

  Maximum

  temperature (°C) 40

A galvanic cell consists of two connected half-cells that can produce an electron flow.

Which combination of standard half-cell pairs would be expected to result in a cell potential of 1.41 V?

• Al electrode with Al(NO₃)₃ & Ag electrode with AgNO₃

• Zn electrode with Zn(NO₃)₂ & Ni electrode with Ni(NO₃)₂

• Ni electrode with Ni(NO₃)₂ & Al electrode with Al(NO₃)₃

• Ag electrode with AgNO₃ & Zn electrode with Zn(NO₃)₂

The reaction below represents the discharge cycle of a standard lead-acid rechargeable car battery.

Pb(s) + PbO₂(s) + 4H⁺(aq) + 2SO₄^2–(aq) → 2PbSO₄(s) + 2H₂O(l)

During the recharge cycle, the pH

• increases and solid Pb is a reactant.

• increases and solid PbO₂ is produced.

• decreases and chemical energy is converted to electrical energy.

• decreases and electrical energy is converted to chemical energy.

Use the following information to answer Questions 4 and 5.

An increasingly popular battery for storing energy from solar panels is the vanadium redox battery. The battery takes advantage of the four oxidation states of vanadium that are stable in aqueous acidic solutions in the absence of oxygen.

A schematic diagram of a vanadium redox battery is shown on the left.

The overall reaction that occurs when the battery is discharging is

• VO²⁺(aq) + 2H⁺(aq) + V²⁺(aq) → VO²⁺(aq) + V³⁺(aq) + H₂O(l)

• VO²⁺(aq) + H₂O(l) + V³⁺(aq) → VO²⁺(aq) + V²⁺(aq) + 2H⁺(aq)

• VO²⁺(aq) + V²⁺(aq) + 2H⁺(aq) → 2V³⁺(aq) + H₂O(l)

• VO²⁺(aq) + V³⁺(aq) → 2VO²⁺(aq)

If air is present, the following half-equations are also relevant.

O₂(g) + 4H⁺(aq) + 4e^– → 2H₂O(l) E⁰ = +1.23 V

VO²⁺(aq) + 2H⁺(aq) + e^– → V³⁺(aq) + H₂O(l) E⁰ = +0.34 V

If air is present, the

• VO²⁺(aq) ion is oxidised to the V²⁺(aq) ion.

• VO²⁺(aq) ion is reduced to the V³⁺(aq) ion.

• V²⁺(aq) ion is oxidised to the VO²⁺(aq) ion.

• VO²⁺(aq) ion is reduced to the VO²⁺(aq) ion.

When the cell is operating

• a gas forms at the Ag electrode.

• the mass of the Ag electrode increases.

• Ag⁺ ions move towards the Fe electrode.

• electrons move from the Ag electrode to the Fe electrode.

The silver oxide-zinc battery is rechargeable and utilises sodium hydroxide, NaOH, solution as the electrolyte. The battery is used as a backup in spacecraft, if the primary energy supply fails.

The overall reaction during discharge is

Zn + Ag₂O → ZnO + 2Ag

When the silver oxide-zinc battery is being recharged, the reaction at the anode is

• 2Ag + 2OH^– → Ag₂O + H₂O + 2e^–

• Ag₂O + H₂O + 2e^– → 2Ag + 2OH^–

• ZnO + H₂O + 2e^– → Zn + 2OH^–

• Zn + 2OH^– → ZnO + H₂O + 2e^–

The following diagrams represent combinations of four galvanic half-cells (G/G²⁺, J/J²⁺, Q/Q²⁺ and R/R²⁺) that were investigated under standard conditions.

Each half-cell consisted of a metal electrode placed in a 1.0 M nitrate solution of the respective metal ion.

The diagrams show the polarity of the electrodes in each half-cell, as determined using an ammeter. The results were then used to determine the order of the E⁰ values of the half-reactions.

Which of the following indicates the order of the half-cell reactions, from the lowest E⁰ value to the highest?

• J/J²⁺, R/R²⁺, G/G²⁺, Q/Q²⁺

• Q/Q²⁺, G/G²⁺, R/R²⁺, J/J²⁺

• R/R²⁺, J/J²⁺, Q/Q²⁺, G/G²⁺

• G/G²⁺, Q/Q²⁺, J/J²⁺, R/R²⁺

Which one of the following galvanic cells will produce the largest cell voltage under standard laboratory conditions (SLC)?

• 
• 
• 
• 

At the start of the day, a student set up a galvanic cell using two electrodes: nickel, Ni, and metal X. This set-up is shown in the diagram on the left.

Consider the following alternative metals that could be used to replace metal X:

1. zinc, Zn 2. lead, Pb 3. cadmium, Cd 4. copper, Cu

At the end of the day, the student checked the colour of the solution in Half-cell 1 and observed that the solution was

a darker green colour.

Which of the alternative metals could cause the colour of Half-cell 1 to become a darker green?

• metals 1 and 3

• metals 2 and 4

• metals 1, 2 and 3

• metals 3 and 4