IB myp 4-5 Chemistry – Practice Questions- All Topics
Topic :Types of chemical reaction-Electrochemical cells
Topic :Types of chemical reaction-Weightage : 21 %
All Questions for Topic :acids and bases,neutral solutions,acid/base reactions,$\mathrm{pH}$ and indicators,formation of salts,uses of salts,redox reactions,reactivity series,extraction of metals and corrosion,electrochemical cells
Question : Types of Chemical Reaction – Electrochemical Cells [15 marks]
Question a [5 marks]
Explain what happens to a voltaic cell when the salt bridge is removed.
▶️ Answer/Explanation
• Ions cannot move between half-cells
• Electron flow stops (circuit breaks)
• No charge exchange possible
• Chemical reactions cease
• Voltage drops to zero
Question b [4 marks]
Describe the relationship between reactivity difference and cell potential.
▶️ Answer/Explanation
• Larger reactivity difference → higher cell potential
• Metals further apart in reactivity series produce greater voltage
• Direct correlation between Δreactivity and voltage output
• Explained by stronger electron transfer tendency
Question c [4 marks]
Write the balanced equation for the reaction between copper and silver ions.
▶️ Answer/Explanation
Cu(s) + 2Ag+(aq) → Cu2+(aq) + 2Ag(s)
• Correct reactants/products
• Proper balancing (2Ag+)
• State symbols included
• Single arrow for complete reaction
Question d [2 marks]
Identify the processes occurring at each electrode.
▶️ Answer/Explanation
Anode: Oxidation (Cu → Cu2+ + 2e–)
Cathode: Reduction (Ag+ + e– → Ag)
Question:
Why do negatively charged anions from the salt bridge move into the anode cell and positively charged cations move into the cathode cell when the half-cells are connected?
▶️Answer/Explanation
Ans: Anions from the salt bridge move into the anode cell to maintain charge balance as electrons are lost from the anode into the external circuit. Cations from the salt bridge move into the cathode to counter balance the electrons that move into the cathode from the external circuit.