Report : Chemical Reactions and Redox Reactions

Title                         : Chemical Reactions and Redox Reactions

Day, date                  : Monday, February 6, 2017

Purpose                    :

1) Study the types of chemical reactions systematically

2) Observe the signs of reaction

3) Write the equation of the reaction correctly

4) Complete the redox reaction of each experiment

Theoretical basis       :

          Chemical reactions are the processes that conserve a group of substances called reactants, into groups of new substances called products. In other words, chemical reation is a reaction that produces a chemical change. Indeed, in many cases, nothing happens when a certain amount of substance is mixed retains its original composition and substance. We need evidence before we can say that a reaction has taken place. Several types of physical evidence required are shown below:Color change, Formation of solids in clear solution, Gas evolution, Evolution or absorption of heat. Although such sorting usually prevents the reaction from occurring, strong evidence still requires a detailed chemical analysis of the reaction mixture to identify all the substances present (Petrucci.2007: 108).        

Generally chemical reactions are classified by type as follows:
1. Reaction of merging

That is the reaction in which two substances merge forming a third substance. The simplest case is if two elements react to form a compound. For example, sodium metal reacts with chlorine gas forming sodium chloride. The chemical equation:

Na _(s) + Cl (g)----> 2NaCl _(s)

2. Decomposition Reactions

That is, a single compound reaction forms two or more new substances. Usually this reaction takes place in high temperatures. Some compounds that can be teruraidengan raise temperatures such as kclo3. This compound if dipanaska will break down into KCl and oxygen gas. The chemical equation:

KClO_{3 (s) --->} 2KCl _(s) + 3O_{2 (g)}

3. Urgent or replacement reaction

That is a reaction in which an element reacts with a compound in place of the element contained in the compound. For example, if iron metal is immersed in a copper (II) nitrate solution, it will settle the copper metal. The chemical equation:

2Fe _(s) + Cu (NO₃) _{2 (aq)} ----> CU _(s) + Fe (NO₃) _{2 (aq)}

4. Metalesis reaction (double formation)

That is a reaction involving the exchange of parts of the reactant. If the reagents are ionic compounds in solution form, the exchange portion is the cation and anion of the compound. For example a colorless potassium iodide solution. The ions in the reacted solution form a yellow precipitate of the lead (II) iodide compound. The chemical equation:

2KCl _(aq) + Pb (No₃) _{3 (aq)} ---> 2KNO_{3 (aq)} + Pbl_{2 (s)}

5.Burning reaction

That is the reaction of a substance with oxygen, usually reacts quickly with the release of heat-forming flame (Sunarya.2010: 47-50).

            Oxidation is a process that results in the number of one or more electrons in a substance (atom, ion and molecule). When the temperature of the dioxidic element, the oxidation state changes to a more positive price, an oxidizing agent is a substance which obtains an electron and in a particular process the substance is reduced. Reduction is a process that results in the loss of one or more electrons from the natural substances (atoms, ions and molecules). When the element temperature is reduced, the oxidation state changes to more negative. Thus a reducing agent is a substance which loses electrons in the process that it is oxidized (svehia.195: 108).

            Determine the redox reaction: in the search for the oxidation number of all elements in a reaction, and can know the reaction is redox and determine the oxidized and reduced elements.

The oxidation numbers of commonly known elements are arranged according to their position in the periodic table:

1.  Metal elements can have positive oxidation numbers, whereas non-metallic elements can have positive or negative oxidation numbers.

2.   The highest oxidation states belonging to the IA-VIIIA group elements are the same as the numbers in the periodic table, for example the halogen is the VIIA group, so the highest possible oxidation number is + 7. Transition metals (class IB, IIIB - VIIIB) usually have several possible oxidation numbers (Raymond, 2004: 84).

Tools and materials :

Tools to be used:

1. Spatula
2. Crush
3. Flame bunsen
4. Test tube
5. Drop pipette
6. Acid Cupboard

Materials to be used:

1.     Mg

2.     CuSO4 ∙ 5H2O crystals

3.     1 ml of 0.01 M AgNO3 solution

4.     0.1 g of Cu powder

5.     1 ml of 0.1 M HCl solution

6.     0.1 g of Mg powders

7.     1 ml of 0.1 M AgNO3 solution

8.     1 ml of a solution of Hg (NO 3) 2 0.1M

9.     1 ml of Al (NO 3) 3 0.1M solution

10. 1 ml of 0.1 M KI solution

11. 1 ml of 0.1M Na3PO4 solution

12. 1 ml of HNO3 0.1M

13. 1 ml of 0.1M H2SO4

14. 1 ml of H3PO4 0.1M

15. 1 drop of phenolphthalein indicator

16. NaOH 0.1M

17. 0.5 ml of 6M H2SO4 solution

18. 0.5 ml of 0.1 M KMnO4 solution

19. 0.1M Na2C2O4 solution

20. 3 ml of 0.1 M NaHSO3 solution

21. Metal Zn

22. Cu Metals

23. ZnSO4 0,5M solution

24. Pb (NO3) 2 0,5M

25. NaNO3 0.5M

26. Metals Mg

27. 10 drops of KI 0.1M

28. Kanji solution 1 drop

29. FeCl3 0.1M

30. H2SO4 0.1M

 Work steps                 :

 

Results and discussion   :

The equation of the reaction	Proof of reaction
A.     Reaction of merging Mg + O2 --> MgO2	Color change from black to brownish
B.     Decomposition Reactions CuSO4.5H2O --> CuSO4 + 5H2O	Color changes from blue to white and there is water vapor
C. Single Replacement Reaction 1.Cu+2AgNO3  --->  Cu(NO3)2+2Ag 2.Mg + 2HCl     ---->   MgCl2 + H2	- to be a precipitate and a fixed color -there is bubbles, Mg is exhausted by HCl and feels hot
D. Multiple Replacement Reaction 1.AgNO3 + KI--> KNO3 + AgI 2.Hg(NO3)2+KI --> 2KNO3 + HgI2 3.AlNO3+ 3KI --> 3KNO3 + AlI3           4.AgNO3+ Na3PO4-->  AgPO4 + 3NaNO3             5.Hg(NO3)2+Na3PO4Hg(PO4)2+  6NaNO3 6.Al(NO3)3+Na3PO4-->AlPO4+3NaNO3	-Ag becomes pale yellow -Hg orange color-Al becomes clear -being brown turbid -being yellow turmeric - becomes clear and deposits occur
E.  Redox reactions 1.Na2C2O4+KMnO4-->2NaMnO4 + KC2O4   2.NaHSO4+ KMnO4 --> NaMnO4 + KSO4 +H2O      3.HCl+ KMnO4 --> KCl + HMnO4	-the color change from white to brown -the color changes from white to green and there is sediment -the color change from black brown to clear brown

Discussion :

A.    Reaction Reactions

In this reaction a substance is combined by burning, so that the substance reacts with O2.

B.     Decomposition Reactions

 In this experiment CuSO4 ∙ 5H2O is described by heating, wherein H 2 O will evaporate until CuSO4 is obtained.

C.     Single Replacement Reaction

In this experiment, there is a substitution of an element to another element, but the substituted element is located further down in the voltaic series so that the substitute element can push the element to be replaced.

D.    Double Replacement Reaction

In the experiment mixed AgNO3, Hg (NO3) 2, Al (NO3) 3 with KI, after reacting then the substance of each experiment can exchange pairs. However, in the reaction Hg (NO3) 2 + KI and Al (NO3) 3 + KI no change whatsoever. This is due to errors on the practitioner who did not perform the trial according to the procedure.

E.  Some Redox Reactions

In this experiment, ZnSO4 mixed with Cu did not occur. This is because Cu is on the right Zn so Cu can not push Zn. For the reaction of NaNO3 + Mg also does not happen this reaction is due to the mixture is not soluble to form precipitate.

Conclusion             :

1.      The types of chemical reactions
Merger / synthesis            : A + Z ----> AZ
Decomposition                 : AZ ----> A + Z
Single replacement           : A + BZ -----> AZ + B
Double replacement          : AX + BZ -----> AZ + BX
Neutralization                   : HX + BOH -----> BX + HOH

2.      Signs of a reaction that is:
A. Sludge
B. The emergence of bubbles / gas
C. Temperature changes
D. Discoloration

3.      The equation of the reaction can be solved by developing the number of substances before and after the reaction

4.      The redox reaction can be synchronized with the half-reaction method of the oxidation equation. Redox reactions are said to be equivalent if the amount of substances before and after the reaction are equal, and the product charge is the same.

Literature  :

Ahmad, Hiskia. 1993. Materi  Pokok Kimia Dasar 1. Jakarta: Depdikbud

Chang, Raymond. 2004. Kimia Dasar. Jakarta: Erlangga

Suehla, G. 1989. Vogel “ Buku Teks Analisa Kualitatif Makro dan Semimikro.Jakarta:  PT.   Kalman   Media Pustaka

Sukardjo. 1985.  Kimia Dasar. Yogyakarta: Bina Ausara

Syukri, S . 1991. Kimia Dasar 1. Bandung : ITP

Attacment :