2. Welcome to Chemistry Learning The … th meeting of the class !!!

4. In X grade, you have ever studied about redox reaction. Do you still remember, what is the meaning of oxidation and reduction reaction?!?

5. What do you know about oxidation number?!? And how to determine the oxidation number of the element?!?

6. LEO SAYS GER

7.  Lose Electrons = Oxidation Sodium is oxidized Gain Electrons = Reduction Chlorine is reduced

8.  - Losing electrons is oxidation, and the substance that loses the electrons is called the reducing agent.  - Gaining electrons is reduction, and the substance that gains the electrons is called the oxidizing agent. Mg is oxidized: loses e -, becomes a Mg 2+ ion Mg (s) + S (s) → MgS (s) Mg is the reducing agent S is the oxidizing agent S is reduced: gains e - = S 2- ion

9. It is easy to see the loss and gain of electrons in ionic compounds, but what about covalent compounds? In water, we learned that oxygen is highly electronegative, so: the oxygen gains electrons (is reduced and is the oxidizing agent), and the hydrogen loses electrons (is oxidized and is the reducing agent)

10. Does each chemical reaction must be equal?!? What do you know about equalization of chemical reaction?!? Does the simple chemical reaction can be equal with spontan method?!?

11.  Learning Objectives After Learning this topic, you are expected to be able to:  Describe how oxidation numbers are used to identify redox reactions.  Balance a redox equation using the oxidation-number- change method.  Balance a redox equation by breaking the equation into oxidation and reduction half-reactions, and then using the half-reaction method.

12. Redox Reaction and Electrochemistry Electrochemical Cell Alectrolysis Cell Redox Reaction Reaction Equalization Cell Potential Standard Reduction Potential Half Reaction Oxidation Number based on including Is cunducted by means of

13. In general, all chemical reactions can be assigned to one of two classes: 1) oxidation-reduction, in which electrons are transferred: Single-replacement, combination, decomposition, and combustion 2) this second class has no electron transfer, and includes all others: Double-replacement and acid-base reactions

14. In an electrical storm, nitrogen and oxygen react to form nitrogen monoxide:  N 2(g) + O 2(g) → 2NO (g) Is this a redox reaction? If the oxidation number of an element in a reacting species changes, then that element has undergone either oxidation or reduction; therefore, the reaction as a whole must be a redox. YES!

15. It is essential to write a correctly balanced equation that represents what happens in a chemical reaction Fortunately, two systematic methods are available, and are based on the fact that the total electrons gained in reduction equals the total lost in oxidation. The two methods: 1) Use oxidation-number changes 2) Use half-reactions

16. Sort of like chemical bookkeeping, you compare the increases and decreases in oxidation numbers. start with the skeleton equation Step 1: assign oxidation numbers to all atoms; write above their symbols Step 2: identify which are oxidized/reduced Step 3: use bracket lines to connect them Step 4: use coefficients to equalize Step 5: make sure they are balanced for both atoms and charge

17.  Please Look at the Video Video

18. What All Reactions that occur in the world are Redox Reactions?!? What method that can be used to equal reaction but not redox reaction?!?

19.  - Reactions in which there has been no change in oxidation number are NOT redox reactions. Examples:

20. A half-reaction is an equation showing just the oxidation or just the reduction that takes place they are then balanced separately, and finally combined Step 1: write unbalanced equation in ionic form Step 2: write separate half-reaction equations for oxidation and reduction Step 3: balance the atoms in the half- reactions (More steps on the next slide)

21. Step 4: add enough electrons to one side of each half-reaction to balance the charges Step 5: multiply each half-reaction by a number to make the electrons equal in both Step 6: add the balanced half-reactions to show an overall equation Step 7: add the spectator ions and balance the equation

22.  Please Look at the Video Video

23. Any Question ?!?

24. who can explain the main topic about this matter?!?

25. 1) The oxidation number change method works well if the oxidized and reduced species appear only once on each side of the equation, and there are no acids or bases. 2) The half-reaction method works best for reactions taking place in acidic or alkaline solution.

26.  Reactions in which there has been change in oxidation number are called redox reactions.  Every redox reactions consists of half reaction (oxidation reaction) and half reaction (reduction reaction).  Oxidation is various types of process that naturally to increase valence from vital element in that system. Initial oxidation is in the form of reaction from elements with oxygen, then with halogen too, and ultimately its vital elements reaction loses its valence electron.  Reduction is hydrogen addition of intake in any substance, oxidation degree depression of any elements in compound, or electron addition in any elements atom.  Redox reaction quotation must be equal between left and right field. The applied method for equalizing redox reaction is oxidation number and half reaction method.

27. Exchange and equalize the following redox reaction equation: a. Zn(s) + SO 4 2- (aq) Zn 2 +(aq) + SO 2 (g) b. Fe 2+ (aq) + MnO 4 - (aq) Fe 3+ (aq) + MnO 2 (s) c. CN - (aq) +MnO 4 - (aq)+H 2 O(l) MnO 2 (s) + CNO - (aq) + OH - (aq)