Oxidation states for elements

 

 

Total marks 30 Question 1 4 marks Determine the oxidation states for each element in the following substances a) Mn042+ b) K2Cr202
Question 2 5 marks Assign oxidation states to each clement in the following equation. Identify which element is being oxidised and reduced and the oxidising and reducing agents. Ni02(s) + Mn(OH)2 (aq) —• Mn203 (s) + Ni(0102
Question 3 5 marks Balance the following chemical equation using the method of half reactions. In each case identify the oxidation and reduction reactions, which element is being oxidised and reduced and the oxidising and reducing agents. MnOe • + S203 2 —• 5406 + Mn 2+
Question 4 4 marks Explain how the dry cell batteries used in watches and calculators work. (Your answer should give a brief description of how the battery is constructed with a diagram, indicating the materials used in the anode and cathode and also the electrolyte. You should also show the reactions that take place at each electrode)
Question 5 Consider the oxidation-reduction reaction: Al(s) + Ni1+ (aq) -+ All’ (aq) + Ni(s) Sketch a galvanic cell that uses this reaction, clearly indicating the direction of electron flow. Which metal ion is reduced? Which metal is oxidised? What half-reaction takes place at the anode in the cell? What half-reaction takes place at the cathode?
6 marks
Question 6 (6 marks) Draw all the structural isomers and give the systematic names for all possible alkanes containing seven carbon atoms.