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QUESTION 1 (12 marks) When zinc metal was placed into a blue solution of copper(II) nitrate the solution became colourless and a red-brown deposit of copper formed on the bottom of the beaker. a) Identify if the reaction that occurred can be classified as a redox reaction. Explain your reasoning. [3 marks] b) When the copper deposited in the reaction was collected and reacted with concentrated nitric acid copper(II) nitrate solution and nitrogen dioxide gas formed. Cu(s) + 4 HNO; (aq) ÔøΩ Cu(NO;) (aq) + 2 NO (g) + 2H O(1) EÔøΩ = +0.46 V 1) Determine the reduction half-equation for this reaction. [2 marks] 11) Determine the standard reduction potential EÔøΩ for the reduction half-equation. [1 mark] c) Apply your understanding of standard reduction potentials to explain why: 1) copper can dissolve in concentrated nitric acid but does not dissolve in concentrated hydrochloric acid. [3 marks] 11) NO is the gaseous product rather than H when copper dissolves in nitric acid. [3 marks]
QUESTION 24 (6 marks) The cell diagram represents a voltaic cell at standard conditions. The copper solution is blue because of the presence of Cu*(aq) ions. The acidified permanganate solution is purple because of the presence of MnO (aq) ions. Half-cell Half-cell ÔøΩÔøΩÔøΩ_ ÔøΩÔøΩ____ Cu(s) | Cu** (aq) | | MnO (aq) | Pt(s) Salt bridge a) Predict which direction the electrons will flow in the voltaic cell by comparing the relative strength of the oxidising agents. Explain your reasoning. [3 marks] b) Determine the standard reduction potential EÔøΩ for the cell. [1 mark] c) Predict two qualitative observations associated with the flow of electrons and the movement of ions in the voltaic cell. [2 marks]
QUESTION 11 The plating of silver is conducted during the operation of the electrochemical cell shown. | Voltage | _ source AgNO (aq) Determine which statement is true for this electrochemical cell. (A) The spoon acts as the cathode. (B) The silver electrode has a negative charge. (C) The silver ions in the solution are oxidised at the spoon. (D) The electrons flow from the spoon to the silver electrode.
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