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gaya2an ngepost experimental report :P
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bismillahirohmanirohiiiiiim...
bingung ni mau nulis apa sebenernya,,tapi daripada blognya kosong melompong jelek banget jadi mau ga mau ya harus mulai rajin posting deh. berhubung saya anak kimia, jadi postingan kali ini ga jauh-jauh dari yang namanya kimia....which is....LAPORAN PRAKTIKUM!!! JENG JENG!
Biar rada gaya and eksyen2 dikit,,laporan yang diposting pake basa inggris aja deh :P
Experimental Report
REDOX AND ELECTROCHEMICAL REACTION
By:
Devy Rohmah Yanti
33150818885
Chemistry Laboratory
Faculty of Mathematics and Science
State University of Jakarta
2009
Redox and Electrochemical Reaction
Purpose
1. to study Eo’s of the selected half reaction
2. to determine the electro motif force between CuSO4 and SnCl2
3. to understand the concept of electrochemical-cell and electrolysis
4. to know the factors that influence electrolysis process
Theory
A metal strip in equilibrium with an aqueous solution of its cations constitutes an electrochemical half-cell. This equilibrium can be represented as:
The tendency for the metal atom to undergo oxidation in aqueous salution is measured by its oxidation potential. When the cation concentration is 1-molal (one mol of ions per 1000 grams of water) at 250C, the potential measured is called the standard oxidation potential (E0) for the half-cell. The table Standard Oxidation Potentials list some common half-cells and their potentials.
The magnitude of E0 indicates the tendency for the oxidation reaction to occur. A large positive potential indicates that the oxidation process has a grater tendency to occur than does the reduction process. Since half-cell reaction are in the state of equilibrium , their behavior is governed by the principles of chemical equilibrium.
When two half-cells of different oxidation potentials are connected, the equilibrium in each half-cell becomes unbalanced. Such an arrangement constitutes an electrochemical cell.
The half cell with the grater oxidation potential will become the anode. Electrons will flow from this half-cell through the connecting wires to the other electrode, the cathode. The total umber of electron lost at the anode will exactly the same as the total number of electrons gained at the cathode.
During oxidation, the positive charges in the solution increase, and the positive charges in the solution decrease.
When doing electrochemical reaction, it is important to use the salt bridge. Salt bridge is provided so that ions can travel from one half-cell to another one.
Equipments and Chemicals needed
Equipments:
1. 250-ml beaker glass
2. salt bridge
3. graduated cylinder
4. voltmeter
5. wire leads
6. test tube
7. medicine drops
8. U-tube
Materials:
1. 0.5 and 1M ZnSO4
2. 0.5 and 1M SnCl2
3. 0.5 and 1M CuSO4
4. Zinc, Lead, Copper, Stan metal strips
5. 0.5 M KI
6. Electrode Carbon
7. PP Indicator
8. Amilum indicator
9. Na2S
Procedure
• Determination of Electromotive force
1. Make Zn half-cell by putting a Zinc metal strip into ZnSO4 aqueous
2. Make Cu half-reaction by putting a Cu metal strip into CuSO4 aqueous
3. Connect both half reaction as manner bellow:
4. Repeat step 1-3, but change the half reaction cell by: Sn and Cu
5. Repeat step 1-3, but change the concentration of the aqueous solution by 1M
6. Record the value that shown by the voltmeter
• Electrolysis of KI aqueous
1. Fill a U-tube with KI aqueous
2. Place carbon electrode into it and connect with battery
3. Add 3 drops of amilum indicator on the anode side, and PP on the cathode side
4. Watch carefully the reaction occur
Report Sheet
• Determination of Electromotive force
1. using Cu(s)
Cu2+ (0.5 M)= 0.5 volt
2. using Cu(s)
Cu2+ (0.5 M)= 0.3 volt
3. using Cu(s)
Cu2+ (1M)= 0.6 volt
After Na2S added : produced stink smell
• Electrolysis of KI
1. Anode: the color of aqueous turn to yellow, smell’s like a betadine antiseptic, added by amillum the color turn to saturated brown
2. Cathode: produce much bubble air, added by PP make the color turn to violet
Analysis
At the determination of electromotive force experiment, Zn metal strip is put into ZnSO4 aqueous and Cu metal strip is put into CuSO4 aqueous, with each concentration is 0.5 M. Electromotive force is produced but the difference between both half-cell. Cu electrode is used as cation, because Cu has bigger reduction potential than Zn. So the reaction can occur spontaneously. It can be seen from the value of Emf, which shows positive value. If the position is changed, Zn as the cation and Cu as the anion, the reaction wont occur. Reaction also can’t be done if Cu is placed into the ZnSO4 aqueous, and vice versa. It is because Cu is more electronegative than Zn. In other words, Cu can keep electrons firmer than Zn, so that Cu can ionize to Cu2+. On the other hand, Zn2+ that comes from ZnSO4 aqueous cant catch electron, so that the redox reaction wont happen.
Based on reaction bellow:
The weight of Cu is getting bigger because of Cu precipitation is formed. It is known as “penyepuhan”.
Based on calculation, E0cell for the reaction above is +1.10. but it is different with the E cell based on the experiment, which is +0.5.
At the second experiment, electrode Sn is put into SnCl2 and Cu in CuSO4 with concentration of each aqueous is 0.5 M. just the same as the previous experiment, Cu is placed as anode, and Sn as cathode because the potential electrode of Cu is bigger than Sn. The reaction between both electrode is shown bellow:
Based on the calculation, the E0cell of the reaction is +0.48 volt. But based on the experiment, it is +0.3 volt.
The third experiment is almost the same as the previous experiments, but one different thing is the concentration used in the experiment. Each of the aqueous has mollarity 1 M. based on experiment, it can produce bigger E0cell than the previous experiment.
The difference value of E0cell between experimental and calculation is because the gel inside salt bridge isn’t fulfilled. So that the ion can’t travel well from one half-cell to the other. It can be happen also because the cathode has oxidized by oxygen and water so it is corroted.
At the electrolysis experiment, anode space change its color to yellow, which is getting saturated at the bottom of the u tube. it also produce iodine smell which can be recognize as the smell of betadine. Meanwhile in the cathode space, there isn’t any color changing, but it produce much air bubble, it is H2 gas. Reaction that occurs in this experiment is:
Conclusion
1. When the cation concentration is 1-molal (one mol of ions per 1000 grams of water) at 250C, the potential measured is called the standard oxidation potential (E0) for the half-cell
2. A large positive potential indicates that the oxidation process has a grater tendency to occur than does the reduction process
3. During oxidation, the positive charges in the solution increase, and the positive charges in the solution decrease
4. Cu electrode is used as cation, because Cu has bigger reduction potential than Zn
5. Reaction at the first experiment is:
8. Based on the calculation, the E0cell of the reaction is +0.48 volt. But based on the experiment, it is +0.3 volt.
9. at the second experiment, Cu is placed as anode, and Sn as cathode because the potential electrode of Cu is bigger than Sn
10. based on the reaction:
11. The difference value of E0cell between experimental and calculation is because the gel inside salt bridge isn’t fulfilled
12. At the electrolysis experiment, anode space produce iodine smell which can be recognize as the smell of betadine
13. in the cathode space, there isn’t any color changing, but it produce much air bubble, it is H2 gas.
14. Reaction that occurs in this experiment is:
Bibliography
Brady, James. 1994. Kimia Universitas Asas dan Struktur edisi ke-5 Jilid I. Jakarta : Binaputra Aksara
Chang, Raymond. 2004. Kimia Dasar Konsep-Konsep Inti edisi ketiga. Jakarta: Erlangga
D.A. Skog. 1990. Analytical Chemistry: An Introduction fifth edition. Philadelphia; Saunders College Publishing
Respati. 1986. Dasar-Dasar Ilmu Kimia. Jakarta: Aksara BARU.
Vogel. 1985. Analisis Anorganik Kualitatif Makro dan Semimikro. Jakarta: PT Kalman Media Pustaka.
karena ketidak-becusan blogger ngopas gambar buatan word,, jadi gambar sel voltanya ga bisa ditampilin deh....
bingung ni mau nulis apa sebenernya,,tapi daripada blognya kosong melompong jelek banget jadi mau ga mau ya harus mulai rajin posting deh. berhubung saya anak kimia, jadi postingan kali ini ga jauh-jauh dari yang namanya kimia....which is....LAPORAN PRAKTIKUM!!! JENG JENG!
Biar rada gaya and eksyen2 dikit,,laporan yang diposting pake basa inggris aja deh :P
Experimental Report
REDOX AND ELECTROCHEMICAL REACTION
By:
Devy Rohmah Yanti
33150818885
Chemistry Laboratory
Faculty of Mathematics and Science
State University of Jakarta
2009
Redox and Electrochemical Reaction
Purpose
1. to study Eo’s of the selected half reaction
2. to determine the electro motif force between CuSO4 and SnCl2
3. to understand the concept of electrochemical-cell and electrolysis
4. to know the factors that influence electrolysis process
Theory
A metal strip in equilibrium with an aqueous solution of its cations constitutes an electrochemical half-cell. This equilibrium can be represented as:
The tendency for the metal atom to undergo oxidation in aqueous salution is measured by its oxidation potential. When the cation concentration is 1-molal (one mol of ions per 1000 grams of water) at 250C, the potential measured is called the standard oxidation potential (E0) for the half-cell. The table Standard Oxidation Potentials list some common half-cells and their potentials.
The magnitude of E0 indicates the tendency for the oxidation reaction to occur. A large positive potential indicates that the oxidation process has a grater tendency to occur than does the reduction process. Since half-cell reaction are in the state of equilibrium , their behavior is governed by the principles of chemical equilibrium.
When two half-cells of different oxidation potentials are connected, the equilibrium in each half-cell becomes unbalanced. Such an arrangement constitutes an electrochemical cell.
The half cell with the grater oxidation potential will become the anode. Electrons will flow from this half-cell through the connecting wires to the other electrode, the cathode. The total umber of electron lost at the anode will exactly the same as the total number of electrons gained at the cathode.
During oxidation, the positive charges in the solution increase, and the positive charges in the solution decrease.
When doing electrochemical reaction, it is important to use the salt bridge. Salt bridge is provided so that ions can travel from one half-cell to another one.
Equipments and Chemicals needed
Equipments:
1. 250-ml beaker glass
2. salt bridge
3. graduated cylinder
4. voltmeter
5. wire leads
6. test tube
7. medicine drops
8. U-tube
Materials:
1. 0.5 and 1M ZnSO4
2. 0.5 and 1M SnCl2
3. 0.5 and 1M CuSO4
4. Zinc, Lead, Copper, Stan metal strips
5. 0.5 M KI
6. Electrode Carbon
7. PP Indicator
8. Amilum indicator
9. Na2S
Procedure
• Determination of Electromotive force
1. Make Zn half-cell by putting a Zinc metal strip into ZnSO4 aqueous
2. Make Cu half-reaction by putting a Cu metal strip into CuSO4 aqueous
3. Connect both half reaction as manner bellow:
4. Repeat step 1-3, but change the half reaction cell by: Sn and Cu
5. Repeat step 1-3, but change the concentration of the aqueous solution by 1M
6. Record the value that shown by the voltmeter
• Electrolysis of KI aqueous
1. Fill a U-tube with KI aqueous
2. Place carbon electrode into it and connect with battery
3. Add 3 drops of amilum indicator on the anode side, and PP on the cathode side
4. Watch carefully the reaction occur
Report Sheet
• Determination of Electromotive force
1. using Cu(s)
Cu2+ (0.5 M)= 0.5 volt
2. using Cu(s)
Cu2+ (0.5 M)= 0.3 volt
3. using Cu(s)
Cu2+ (1M)= 0.6 volt
After Na2S added : produced stink smell
• Electrolysis of KI
1. Anode: the color of aqueous turn to yellow, smell’s like a betadine antiseptic, added by amillum the color turn to saturated brown
2. Cathode: produce much bubble air, added by PP make the color turn to violet
Analysis
At the determination of electromotive force experiment, Zn metal strip is put into ZnSO4 aqueous and Cu metal strip is put into CuSO4 aqueous, with each concentration is 0.5 M. Electromotive force is produced but the difference between both half-cell. Cu electrode is used as cation, because Cu has bigger reduction potential than Zn. So the reaction can occur spontaneously. It can be seen from the value of Emf, which shows positive value. If the position is changed, Zn as the cation and Cu as the anion, the reaction wont occur. Reaction also can’t be done if Cu is placed into the ZnSO4 aqueous, and vice versa. It is because Cu is more electronegative than Zn. In other words, Cu can keep electrons firmer than Zn, so that Cu can ionize to Cu2+. On the other hand, Zn2+ that comes from ZnSO4 aqueous cant catch electron, so that the redox reaction wont happen.
Based on reaction bellow:
The weight of Cu is getting bigger because of Cu precipitation is formed. It is known as “penyepuhan”.
Based on calculation, E0cell for the reaction above is +1.10. but it is different with the E cell based on the experiment, which is +0.5.
At the second experiment, electrode Sn is put into SnCl2 and Cu in CuSO4 with concentration of each aqueous is 0.5 M. just the same as the previous experiment, Cu is placed as anode, and Sn as cathode because the potential electrode of Cu is bigger than Sn. The reaction between both electrode is shown bellow:
Based on the calculation, the E0cell of the reaction is +0.48 volt. But based on the experiment, it is +0.3 volt.
The third experiment is almost the same as the previous experiments, but one different thing is the concentration used in the experiment. Each of the aqueous has mollarity 1 M. based on experiment, it can produce bigger E0cell than the previous experiment.
The difference value of E0cell between experimental and calculation is because the gel inside salt bridge isn’t fulfilled. So that the ion can’t travel well from one half-cell to the other. It can be happen also because the cathode has oxidized by oxygen and water so it is corroted.
At the electrolysis experiment, anode space change its color to yellow, which is getting saturated at the bottom of the u tube. it also produce iodine smell which can be recognize as the smell of betadine. Meanwhile in the cathode space, there isn’t any color changing, but it produce much air bubble, it is H2 gas. Reaction that occurs in this experiment is:
Conclusion
1. When the cation concentration is 1-molal (one mol of ions per 1000 grams of water) at 250C, the potential measured is called the standard oxidation potential (E0) for the half-cell
2. A large positive potential indicates that the oxidation process has a grater tendency to occur than does the reduction process
3. During oxidation, the positive charges in the solution increase, and the positive charges in the solution decrease
4. Cu electrode is used as cation, because Cu has bigger reduction potential than Zn
5. Reaction at the first experiment is:
8. Based on the calculation, the E0cell of the reaction is +0.48 volt. But based on the experiment, it is +0.3 volt.
9. at the second experiment, Cu is placed as anode, and Sn as cathode because the potential electrode of Cu is bigger than Sn
10. based on the reaction:
11. The difference value of E0cell between experimental and calculation is because the gel inside salt bridge isn’t fulfilled
12. At the electrolysis experiment, anode space produce iodine smell which can be recognize as the smell of betadine
13. in the cathode space, there isn’t any color changing, but it produce much air bubble, it is H2 gas.
14. Reaction that occurs in this experiment is:
Bibliography
Brady, James. 1994. Kimia Universitas Asas dan Struktur edisi ke-5 Jilid I. Jakarta : Binaputra Aksara
Chang, Raymond. 2004. Kimia Dasar Konsep-Konsep Inti edisi ketiga. Jakarta: Erlangga
D.A. Skog. 1990. Analytical Chemistry: An Introduction fifth edition. Philadelphia; Saunders College Publishing
Respati. 1986. Dasar-Dasar Ilmu Kimia. Jakarta: Aksara BARU.
Vogel. 1985. Analisis Anorganik Kualitatif Makro dan Semimikro. Jakarta: PT Kalman Media Pustaka.
karena ketidak-becusan blogger ngopas gambar buatan word,, jadi gambar sel voltanya ga bisa ditampilin deh....