EXPERIMENT I
THERMAL DECOMPOSITION CARBONATE
I.
Destination
The purpose of this experiment is
as follows:
Students can study the decomposition of sodium hydrogen carbonate by heating and using hydrogen chloride titration.
Students can study the decomposition of sodium hydrogen carbonate by heating and using hydrogen chloride titration.
II.
Time and Place of Execution
Ø
Day, Date : Tuesday, December18, 2012
Ø
Time : 13:00 – Finish
Ø Setting : Laboratory of Advanced Chemical
FKIP UNTAD
III.
Observation
Results
The observations that can be obtained in this experiment are as follows:
1. Thermal decomposition of carbonate (NaHCO3)
Test tubes Weight : 18.88 grams
Mass NaHCO3 were weighed : 1.06 grams
Weight + NaHCO3 reaction tubes before heated : 19.94 grams
Weight + NaHCO3 reaction tube after heating : 19.76 grams
Mass (Na2CO3 + NaHCO3 that has reacted) : 0.18 grams
Test tubes Weight : 18.88 grams
Mass NaHCO3 were weighed : 1.06 grams
Weight + NaHCO3 reaction tubes before heated : 19.94 grams
Weight + NaHCO3 reaction tube after heating : 19.76 grams
Mass (Na2CO3 + NaHCO3 that has reacted) : 0.18 grams
2. Titration of Na2CO3 with HCl
a. titration I
Na2CO3 Volume : 10 ml
HCl Volume : 13.10 ml
Colors before the titrated solution : Yellow
solution after titrasion Color : Orange
b. titration II
Na2CO3 Volume : 10 ml
HCl Volume : 12.9 ml
Colors before the titrated solution : Yellow
solution after titrasion Color : Orange
c. titration III
Na2CO3 Volume : 10 ml
HCl Volume : 12.75 ml
Colors before the titrated solution : Yellow
solution after titrasion Color : Orange
a. titration I
Na2CO3 Volume : 10 ml
HCl Volume : 13.10 ml
Colors before the titrated solution : Yellow
solution after titrasion Color : Orange
b. titration II
Na2CO3 Volume : 10 ml
HCl Volume : 12.9 ml
Colors before the titrated solution : Yellow
solution after titrasion Color : Orange
c. titration III
Na2CO3 Volume : 10 ml
HCl Volume : 12.75 ml
Colors before the titrated solution : Yellow
solution after titrasion Color : Orange
IV.
Reactions
Ø 
2NaHCO3(s) Δ
Na2CO3(aq) +
H2O(g) + CO2(g)
2NaHCO3(s) Δ
Na2CO3(aq) +
H2O(g) + CO2(g)
Ø 
Na2CO3(aq)
+ HCl(aq) NaCl(aq)
+ H2O(aq) +
CO2(g)
Na2CO3(aq)
+ HCl(aq) NaCl(aq)
+ H2O(aq) +
CO2(g)
V.
Calkulatins
Ø Thermal Decomposition of NaHCO3
Ø Titrasion Na2CO3
+ HCl
§ Erlenmeyer
1
§ Erlenmeyer
2
§ Erlenmeyer
3
VI.
DISCUTION
In this experiment there are two ways in which the thermal decomposition of carbonate that thermal decomposition of carbonate (NaHCO3) and titrate Na2CO3 with HCl (Pursitasari, 2011).
The method used is the method of gravimetric and titrimetric methods. Gravimetric method is a method of quantitative chemical analysis by weighing and separation of an element or compound is formed in the form of a pure as possible while the titrimetric method is a method of quantitative chemical analysis based on the measurement of a volume of the titration (Pursitasari, 2011).
The method used is the method of gravimetric and titrimetric methods. Gravimetric method is a method of quantitative chemical analysis by weighing and separation of an element or compound is formed in the form of a pure as possible while the titrimetric method is a method of quantitative chemical analysis based on the measurement of a volume of the titration (Pursitasari, 2011).
A. Thermal Decomposition of Carbonates
Thermal decomposition of carbonate is a carbonate decomposition by heating. The method used the gravimetric method is a method of quantitative chemical analysis by weighing and separation of an element or compound in the form of a considerable period as pure as possible (Pursitasari, 2011). In this experiment the first thing to do is weigh a clean test tube and dried to determine its mass is 18.88 grams. Then weighed to determine the mass of solid NaHCO3 is 1.06 grams, so that the mass of the test tube were added solid NaHCO3 before being heated is 19.94 grams. Further heating the test tubes containing solid NaHCO3 using tube clamps on the electric bath. In this treatment the heating function aims to evaporate the water content contained in solid NaHCO3 and also accelerate the reaction to decompose NaHCO3. After the steam contained in the neck tube and heating it gently to evaporate the water is condensed so that the test tube and the solid is in it in the dry state. Then put the test tube in a test tube rack and silence for a moment to cool the test tube and solid NaHCO3 at room temperature. The purpose is so that cooled laruatan Na2CO3 HCl can be titrated with a known concentration and has a boiling point is low.Weigth obtained after heating is 19.80 grams and is solid when heated produce Na2CO3 NaHCO3, H2O, and CO2. So that it can be seen that the mass of Na2CO3 and NaHCO3 did not react as much as 0.14 grams. The results obtained in the experiments that have been done differently to that in the literature. In the calculations, the results of 0.636 grams (Catherine, 2009).
The difference is due to the occurrence of an error at the time of the experiment at which time warming up too fast so not all of the water content in the solid NaHCO3 to evaporate perfectly. It is known that the methods used in these experiments is that the gravimetric method is a method of quantitative chemical analysis based on separation and weighing of an element or compound in the form of a considerable period as pure as possible (tutus, 2009).
Thermal decomposition of carbonate is a carbonate decomposition by heating. The method used the gravimetric method is a method of quantitative chemical analysis by weighing and separation of an element or compound in the form of a considerable period as pure as possible (Pursitasari, 2011). In this experiment the first thing to do is weigh a clean test tube and dried to determine its mass is 18.88 grams. Then weighed to determine the mass of solid NaHCO3 is 1.06 grams, so that the mass of the test tube were added solid NaHCO3 before being heated is 19.94 grams. Further heating the test tubes containing solid NaHCO3 using tube clamps on the electric bath. In this treatment the heating function aims to evaporate the water content contained in solid NaHCO3 and also accelerate the reaction to decompose NaHCO3. After the steam contained in the neck tube and heating it gently to evaporate the water is condensed so that the test tube and the solid is in it in the dry state. Then put the test tube in a test tube rack and silence for a moment to cool the test tube and solid NaHCO3 at room temperature. The purpose is so that cooled laruatan Na2CO3 HCl can be titrated with a known concentration and has a boiling point is low.Weigth obtained after heating is 19.80 grams and is solid when heated produce Na2CO3 NaHCO3, H2O, and CO2. So that it can be seen that the mass of Na2CO3 and NaHCO3 did not react as much as 0.14 grams. The results obtained in the experiments that have been done differently to that in the literature. In the calculations, the results of 0.636 grams (Catherine, 2009).
The difference is due to the occurrence of an error at the time of the experiment at which time warming up too fast so not all of the water content in the solid NaHCO3 to evaporate perfectly. It is known that the methods used in these experiments is that the gravimetric method is a method of quantitative chemical analysis based on separation and weighing of an element or compound in the form of a considerable period as pure as possible (tutus, 2009).
B. Titration of Na2CO3 with HCl
Titration is the process of measuring the volume of the test solution / standard solution required to reach the end point titration (tutus, 2009). In this treatment method used is the titrimetric method is a method of quantitative chemical analysis based on the measurement of a volume of the titration. In this experiment the first treatment of solid NaHCO3 was poured in a beaker and then rinse the tube with distilled water two to three times and then pour it back into the beaker. Rinse two to three times as much as aiming to ensure that all solid Na2CO3 soluble in water and not left on the wall of the test tube so that the mass of solids that react Na2CO3 did not experience a reduction. Based on existing literature when added to H2O Na2CO3 solution will be cloudy or less soluble. The results obtained in this experiment is similar to that of the literature. But when heated which the solution became clear. This happens because Carbonate from elements other than lithium in Group 1 was not decomposed at room temperature even at higher temperatures they will decompose, decomposition temperature increases as you go down the Group 1 (Clark, 2007).
Titration is the process of measuring the volume of the test solution / standard solution required to reach the end point titration (tutus, 2009). In this treatment method used is the titrimetric method is a method of quantitative chemical analysis based on the measurement of a volume of the titration. In this experiment the first treatment of solid NaHCO3 was poured in a beaker and then rinse the tube with distilled water two to three times and then pour it back into the beaker. Rinse two to three times as much as aiming to ensure that all solid Na2CO3 soluble in water and not left on the wall of the test tube so that the mass of solids that react Na2CO3 did not experience a reduction. Based on existing literature when added to H2O Na2CO3 solution will be cloudy or less soluble. The results obtained in this experiment is similar to that of the literature. But when heated which the solution became clear. This happens because Carbonate from elements other than lithium in Group 1 was not decomposed at room temperature even at higher temperatures they will decompose, decomposition temperature increases as you go down the Group 1 (Clark, 2007).
The next step is the solution transferred into a volumetric flask and dilute by adding distilled water up to the limit of the measuring flask and shake until the solid Na2CO3 solution so that the resulting solution becomes clear. The purpose of the shuffle is done quickly so that the solution is mixed and homogenize the solution. The results obtained can be different from the theory, which in theoretical solid Na2CO3 when mixed with water will produce cloudy because it is poorly soluble in water. However, the experiments have been conducted the results that can be obtained is the solution became clear. This occurs because the effect of heating is too fast and at solids that cause turbidity reaction proceeds rapidly that the solution became clear (Rohaeti, 2008).
In the subsequent treatment to prepare a burette then
fill the burette with standard HCl solution to limit the measure to the buret
and drain a little solution to remove the empty air. Further solutions include
Na2CO3- into three
erlenmeyer each 10 ml and menitrasinya with HCl solution. HCl solution in this
experiment is the standard solution is a solution of known concentration for
sure. In the titration of an acid solution is used as HCl is a strong acid HCl
here to titrate Na2CO3 which is a weak base, wherein the
compound is derived from sodium (Na) which is a strong base and a weak acid CO2.
Dilakukanya titration three times yaituagar laruatan Na2CO3 HCl
can be titrated with a known concentration to obtain the second value of Na2CO3
mass produced in the thermal decomposition of thermally stable because the Na2CO3
solution does not decompose when heated again. Then in each flask erlenmeyer
1.2 and 3, added with 3 drops of methyl orange indicator and color of the
solution obtained at each erlenmeyer before titrated ie yellow and after the
titrated solution at erlenmeyer 1 changes color to reddish orange, while the
second erlenmeyer and 3 turn into the color orange. This difference occurs
because the first titration erlenmeyer 1 lack of accuracy at the time of the
titration so that the results are not in accordance with the literature. The
existence of this color change indicates that the endpoint of a titration was
achieved. The purpose of adding methyl orange indicator is to know that the
endpoint has been reached with a marked color change in the solution titrated
had a stretch where methyl orange pH 3.1 to 4.4 which is acidic and Na2CO3
is a salt that is derived from a weak base NaOH and H2CO3
and then added with HCL is a strong acid so obtained solution is acidic. So in
this experiment using methyl orange indicator. Because in doing titrations we
should use indicators that change color around the equivalence point of the
titration. The results obtained, for the first titration volume of HCl required
to titrate Na2CO3 solution in the erlenmeyer 1 of 15.2 mL, the second titration
volume HCl required to titrate Na2CO3 solution to the
erlenmeyer 2 is at 14.5 mL and for third titration or last volume of HCL
required to titrate a solution of Na2CO3 in erlenmeyer 3
is equal to 14.75 mL. In the calculations, the mass of Na2CO3 obtained
results for the three treatments in a row that is equal to 0.081 grams, 0.076
grams and 0.078 grams. So that the average weight of the obtained mass Na2CO3
titration was 0.078 grams. Meanwhile, based on the calculation of the titration
process on the average mass of literature results obtained 0.018 g Na2CO3,
From the titration volume can be seen that the weight of Na2CO3crystals
differ from the results of the titration and gravimetric this is because the
concentration is so small that Na2CO3gained weight too
small (Anonymous, 2010).
From both experimental methods used there can be seen the thermal stability of the two compounds. Where the stability of the NaHCO3 to Na2CO3,NaHCO3 terms of polarity that is more stable and more polar because it contains hydrogen than Na2CO3containing no hydrogen element because it has undergone evaporation. Hydrogen carbonate group 1 is quite stable in the solid state, although easy to decompose when heated. A small positive ion has a lot of cargo that are arranged in a small volume of space especially if the ion has more than one positive charge. Ion has a high charge density and has a great distortion effect to any negative ion located nearby. This is due to the smaller positive ions, the higher the charge density, and the greater the effect will be caused to the carbonate ion. The further down the Group, the positive ions bigger so it has less effect on carbonate ions nearby. As a consequence, more heat is required to release carbon dioxide and form metal oxides. Polarization hydrogen carbonate (NaHCO3) exactly as carbonate. Positive ions are smaller at the top of Group 1 is stronger in polarizes hydrogen carbonate ions than positive ions are larger at the bottom of group 1 (Clark, 2007).
Of the two methods used the most
appropriate method is used to determine the mass of the gravimetric method is a method of quantitative chemical analysis by weighing and separation of an element or compound in the form of a considerable period as pure as possible. Because the results are closer than titrimetric method, this is
because NaHCO3 used solid form (Clark, 2007).
VI. CONCLUSION
The conclusion that can be diatrik in this experiment are as follows:
1. Sodium hydrogen carbonate (NaHCO3) decomposes into simpler compounds through the heating process. These compounds are formed Na2CO3, H2O and CO2
2. The method used is the method of gravimetric and titrimetric methods, the results obtained for the mass of Na2CO3 is 0.742 grams and 0.078 gram.
The conclusion that can be diatrik in this experiment are as follows:
1. Sodium hydrogen carbonate (NaHCO3) decomposes into simpler compounds through the heating process. These compounds are formed Na2CO3, H2O and CO2
2. The method used is the method of gravimetric and titrimetric methods, the results obtained for the mass of Na2CO3 is 0.742 grams and 0.078 gram.
DAFTAR PUSTAKA
Anonim. 2010. Dekomposisi Thermal Karbonat.
(http://putrikeongdanpangerankudaputih.blogspot.com/2010/10/pembuatan-natrium-tiosulfat.html).
Diakses tanggal 28 November 2012.
Chaterine. 2009. Natrium Karbonat.
: 28 November 2012.
Pursitasari, Indarini
Dwi. 2011. Kimia Analisis Kuantitatif.
Universitas Tadulako. Palu.
Rohaeti. 2008. Kimia
Anorganik Universitas. Wahyu Media. Surabaya.
Penanggung
Jawab Mata Kuliah Kimia Anorganik I. 2012. Penuntun Praktikum Kimia Anorganik I. Universitas Tadulako. Palu
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