basic concept in chemistry

1. REDOX 1.A.DEFINATION Transfer of electrons Oxidation is reduction is PROCESS WHERE ELECTRON IS RELEASED PROCESS WHERE ELECTRON IS GAINED

10. Question 2 Iron(II) chloride reacts with chlorine in a redox reaction

25. a) Which electrode behave as negative electrode? Why? - + 3.

26. a) Which electrode behave as negative electrode? Why? A because iodide ions undergoes oxidation where it lose electrons, the electrons are negatively charged causing it to be negative electrode

27. b) Draw direction for electron flow in the outer circuit

28. c) Write out the rough equation first to show reactants and the products d) Put arrows on your equation above to show oxidation reaction and reduction reaction on your answer in c) above OXIDATION REDUCTION

29. e) What substance is oxidized? Explain your answer in terms of electron transfer Iodide ions because it lose electron

30. f) What substance is reduced? Explain your answer in terms of electron transfer Dichromate ions because it accept electrons

32. h) Write overall equation 6I - + Cr 2 O 7 2- + 14H +  2Cr 3+ + 7H 2 O + 3I 2

33. i) State your observations during the experiment at i)Rod A ii)Rod B Dark brown solution formed Orange solution turns to green solution

34. j)How do you test the presence of iodine formed at rod A? OR Add 2 cm 3 tetrachloromethane to iodine solution, shake well then purple solution formed at lower layer Add a few drops of starch solution, a blue-black solution formed

40. Why does the iron surface at the centre of water droplet behave as anode (negative electrode)? Because here iron atom release electron

43. Write half equation at the anode Fe Fe 2+ + 2e Where does the iron(II) ions formed from the reaction go to? Iron (II) ions dissolve in water