Stoichiometric Analysis of Thermal Decomposition
Reaction of Sodium Bicarbonate
Name
:
Muhammad Haziq bin Abd Shukur
Matrix Number
:
2021132209
Lecturer’s Name
:
Dr Nik Raikhan Nik Him
Date
:
30/12/2021
Group
:
EH2202
Submit to
: Dr Nik Raikhan Nik Him
Student’s Name
: Muhammad Haziq bin Abd Shukur
Student ID
: 2021132209
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Title
Abstract/ Summary
Introduction
Objectives
Theory/ Literature review
Apparatus/ Material
Procedure
Result
Calculation
Discussion
Conclusion
Recommendation
Reference/ Appendix
Total Marks
Remarks
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Checked By
:
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Date By
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Allocated Marks (%)
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10
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10
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100
Marks
Table of Contents
1.0 Summary ........................................................................................................................ 4
2.0 Introduction .................................................................................................................... 5
3.0 Objective ........................................................................................................................ 5
4.0 Theory ............................................................................................................................ 6
5.0 Methodology .................................................................................................................. 8
5.1 Apparatus ................................................................................................................... 8
5.2 Material .................................................................................................................. ..10
5.3 Procedure ............................................................................................................... ..10
5.4 Safety precautions .................................................................................................. ..10
6.0 Result ........................................................................................................................... 11
7.0 Calculations ................................................................................................................ 12
7.1 Stoichiometric mass predictions for each possible reaction .................................... 12
7.2 Percent yield of solid product. ................................................................................. 12
7.3 Percent error of experiment .................................................................................... 13
8.0 Discussion .................................................................................................................... 14
9.0 Conclusion ................................................................................................................... 16
10.0 Recommendation ....................................................................................................... 16
11.0 References .................................................................................................................. 17
Stoichiometric Analysis of Thermal Decomposition Reaction of Sodium
Bicarbonate
1.0 Summary
The purpose of the experiment was to quantify the decomposition of sodium bicarbonate by
applying heat. Therefore, this experiment was carried out to identify the correct chemical
components of decomposition by applying heat. Baking soda (sodium bicarbonate, NaHCO3)
is a solid or granulated sodium bicarbonate.[Frederick John, 2018] Cakes, cookies, muffins,
and cupcakes are a few types of baked goods that don't require yeast. [Bakerpedia, 2018]
The decomposition of sodium bicarbonate has three possible reactions which are produced
solid sodium hydroxide, solid sodium oxide and solid sodium carbonate. Therefore, the
selection of correct reaction is selected by using the stoichiometry method which the mass of
the product can be obtained theoretically and compared with the mass of sodium bicarbonate
after heating. In this experiment, reaction 3 which produced solid sodium carbonate is the
most correct reaction. Since the mass stoichiometry of sodium carbonate in this reaction is
the closest one with the mass of sodium bicarbonate obtained after heating.
4
2.0 Introduction
In chemistry and in the nature of chemistry, stoichiometry has been the most important
and fundamental subject. The principle of mass conservation guides stoichiometry in a
chemical reaction, which specifies that in scenarios where the reactants and products have a
typical ratio of whole integers, the total mass of the reactants equals the total mass of the
products. [Joseph Nijmeh, 2020] In the industry the number of materials required, and the
number of products are calculated. It is estimated produced by a specific reaction and
assistance in assessing profitability. The main question raised in this particular experiment is
what the correct chemical components of decomposition are by applying heat. Stoichiometry
is a concept that defines the connection between the amounts of chemicals used to make and
break a product during a chemical reaction. [Santa Monica College, 2021] The decomposition
of sodium bicarbonate has three possible reactions which are produced solid sodium
hydroxide, solid sodium oxide and solid sodium carbonate. Therefore, the selection of correct
reaction is selected by using the stoichiometry method which the mass of the product can be
obtained theoretically and compared with the mass of sodium bicarbonate after heating. Next,
the main aim of this experiment is to find out the decomposition reaction that occurred during
the experiment, calculate the per cent error and the percent yield of the experiment. Finally,
the overview of this experiment is about the decomposition reaction of sodium bicarbonate
when heat is applied.
3.0 Objective
The uttermost objective of this experiment is to quantify the chemical components in
sodium bicarbonate upon decomposition using heat. In the relation to that, there are a few
sub-objectives that need to be determined. Firstly, we have to obtain the decomposition
reaction that occurred during the experiment. Secondly, we need to calculate the percent
error and the percent yield of the experiment.
5
4.0 Theory
Stoichiometry is based on the law of mass conservation which establishes that the
overall mass of a reactant corresponds to the total mass of the products, where the ratios
of the reactor and product quantities usually constitute a ratio. We can evaluate the mole
ratio by looking at the coefficients in front of expressions in a balanced chemical equation.
[Anne Marie Helmenstine, 2021] According to the rule of conservative mass, mass is
conserved during a chemical reaction when the total mass of the reactants matches the
total mass of the products. [Boundless Chemistry, 2014] Meanwhile, Proust's law, or the
law of definite proportions, says that a chemical compound always contains the same
mass ratio of its parts.[Erik Gregersen, 2021] The mol and mole ratio of substances of a
balanced chemical equation which is converted into the desired unit of substance required
is determined by the stoichiometry of a reaction.
Figure 1: Baking soda
Baking soda decomposes, and carbon dioxide is released when the sodium
bicarbonate temperature exceeds around 50°C. During the bakery process, there are
three potential chemical reactions. All three of the following reactions are potentially
possible and you must decide the right decomposition. In a chemical equation, the
stoichiometric coefficient is expressed as the number in front of the atoms, ions, or
molecules. They are incredibly effective for balancing the chemical equation on both
reactant and product sides since they indicate the mole ratio between reactants and
products. [Joseph Nijmeh, 2020]
Possible Decomposition Reactions:
•
Sodium Bicarbonate (s) → Sodium Hydroxide(s) + Carbon Dioxide (g)
NaHCO3(s) → NaOH(s) + CO2(g)
•
Sodium Bicarbonate (s) → Sodium Oxide (s) + Carbon Dioxide (g) + Water (g)
2NaHCO3(s) → Na2O(s) +2CO2(g)+H2O
•
Sodium Bicarbonate (s) → Sodium Carbonate (s) + Carbon Dioxide (g) + Water (g)
6
2NaHCO3(s) → Na2CO3(s) +CO2(g)+H2O
But the first thing to look out for is to balance the chemical equation to make some
stoichiometric determinations. So, we can easily calculate the stoichiometric relationship
between the number of moles in the reactants and the number of moles in the products. It can
calculate the moles of a material after the molar mass has been calculated and vice versa.
[Boundless.com, 2014] Look below equation:
2NaHCO₃ (s) → Na₂O (s) + 2CO2 + H₂O
The equilibrium equation shows that the sodium bicarbonate stoichiometric coefficient
is 2, while sodium oxide is 1, CO2 is 2 and water is 1. The stoichiometric ratio, also simply
called "mole ratio" or "molar ratio" between NaHCO3, Na2O and CO2, is therefore 2:1:2:1. In
the case of reactants in their molar ratios, they will react entirely with each other and there will
be no reactant left after the reaction is complete. Reactants, however, will not mix in such ideal
stoichiometric quantities in most real-world circumstances. In most situations, the first reactant
to be consumed completely in the reaction would eventually stop the reaction. This reactant
is called limited reactant.
We can see that stoichiometry has a variety of important applications from this brief
definition. The number of moles of product(s) to be produced during each reaction and the
number of moles of the reactant(s) to be consumed, as we can see, can be calculated by
balancing chemical equations and calculating the stoichiometric coefficients. Stoichiometry
can also be used to make useful decisions on reactant restriction and to compute the excess
reactant(s) remaining after a specific reaction is over.
7
5.0 Methodology
Figure 2: Setup for decomposition process of baking soda
5.1 Apparatus
1.Porcelain Crucible
2.Crucible Tongs
3.Balance Pan
4.Clay Triangle
8
5.Spatula
6.Bunsen Burner
7.Retort Stand
8.Wire gauze and Tripod Stand
9.Thermometer
9
5.2 Materials
1.Baking soda (Sodium Bicarbonate , NaHCO3) (Solid)
5.3 Procedure
1.All necessary masses were recorded throughout the experiment
2. The empty crucible was placed on the balance pan and the tare/reset button was
pressed. The mass of the empty crucible was recorded.
3. Some baking soda (between 3-6 grams) was measured into the crucible. The mass
was recorded.
4. The ring stand was assembled with circular ring support. The clay triangle was placed
on top of the ring support and the crucible containing the baking soda was placed on top
of the clay triangle.
5. The crucible and its contents were heated with the Bunsen burner for ten minutes. A
spatula was used to carefully break up clumps that form during heating. Clumps have
been broken during the heating.
6. The mass, crucible and its contents were measured. The mass of the product was
reported.
5.4 Safety precautions
•
Use caution when working with Bunsen burner
•
Must wear safety goggles while experimenting
•
Use heat resistant gloves if necessary
•
Do not touch the crucible or any metal that may remain hot
•
Please read and review Material Safety Data Sheet (MSDS) for additional safety ,
handling and disposal information before experimenting.
10
6.0 Results
Before heat decomposition
Weight (g)
Crucible
12.77
Crucible + Sodium bicarbonate
17.30
Sodium bicarbonate
4.53
Table 6.1: Table of the data of before heat decomposition.
After heat decomposition
Weight (g)
Crucible + Sodium bicarbonate
15.70
Sodium bicarbonate
2.93
Table 6.2: Table of the data of after heat decomposition.
Substance
Theoretical mass (g)
Percent yield (%)
NaOH
2.1571
135
Na2O
1.6718
175
Na2CO3
2.8582
103
Table 6.3: Theoretical mass and percent yield for each solid product
Substance
Percent Error (%)
NaOH
35.83
Na2O
75.26
Na2CO3
2.51
Table 6.4: Theoretical mass and percent yield for each solid product
11
7.0 Calculations
To calculate the mass of sodium bicarbonate:
𝑀𝑎𝑠𝑠 𝑜𝑓 𝑠𝑜𝑑𝑖𝑢𝑚 𝑏𝑖𝑐𝑎𝑟𝑏𝑜𝑛𝑎𝑡𝑒 = (𝑚𝑎𝑠𝑠 𝑜𝑓 𝑐𝑟𝑢𝑐𝑖𝑏𝑙𝑒 + 𝑠𝑜𝑑𝑖𝑢𝑚 𝑏𝑖𝑐𝑎𝑟𝑏𝑜𝑛𝑎𝑡𝑒) − 𝑚𝑎𝑠𝑠 𝑐𝑟𝑢𝑐𝑖𝑏𝑙𝑒
Mass before heat decompostion
Mass after heat decompostion
17.30𝑔 − 12.77𝑔 = 4.53𝑔
15.70𝑔 − 12.77𝑔 = 2.93𝑔
7.1 Stoichiometric mass predictions for each possible reaction
1st possible decomposition reaction
NaHCO3(s) → NaOH(s) + CO2(g)
4.53𝑔𝑁𝑎𝐻𝐶𝑂3 1 𝑚𝑜𝑙𝑒 𝑁𝑎𝐻𝐶𝑂3
1 𝑚𝑜𝑙𝑒 𝑁𝑎𝑂𝐻
40𝑔 𝑁𝑎𝑂𝐻
×
×
×
= 𝟐. 𝟏𝟓𝟕𝟏𝒈 𝑵𝒂𝑶𝑯
1
84 𝑔 𝑁𝑎𝐻𝐶𝑂3
1 𝑚𝑜𝑙𝑒 𝑁𝑎𝐻𝐶𝑂3 1 𝑚𝑜𝑙𝑒 𝑁𝑎𝑂𝐻
2nd possible decomposition reaction
2NaHCO3(s) → Na2O(s) +2CO2(g)+H2O
4.53𝑔𝑁𝑎𝐻𝐶𝑂3 1 𝑚𝑜𝑙𝑒 𝑁𝑎𝐻𝐶𝑂3
1 𝑚𝑜𝑙𝑒 𝑁𝑎2𝑂
62𝑔 𝑁𝑎2𝑂
×
×
×
= 𝟏. 𝟔𝟕𝟏𝟖𝒈 𝑵𝒂𝟐𝑶
1
84 𝑔 𝑁𝑎𝐻𝐶𝑂3
2 𝑚𝑜𝑙𝑒 𝑁𝑎𝐻𝐶𝑂3 1 𝑚𝑜𝑙𝑒 𝑁𝑎2𝑂
3rd possible decomposition reaction
2NaHCO3(s) → Na2CO3(s) +CO2(g)+H2O
4.53𝑔𝑁𝑎𝐻𝐶𝑂3 1 𝑚𝑜𝑙𝑒 𝑁𝑎𝐻𝐶𝑂3 1 𝑚𝑜𝑙𝑒 𝑁𝑎2𝐶𝑂3 106𝑔 𝑁𝑎2𝐶𝑂3
×
×
×
= 𝟐. 𝟖𝟓𝟖𝟐𝒈 𝑵𝒂𝟐𝑪𝑶𝟑
1
84 𝑔 𝑁𝑎𝐻𝐶𝑂3
2 𝑚𝑜𝑙𝑒 𝑁𝑎𝐻𝐶𝑂3 1 𝑚𝑜𝑙𝑒 𝑁𝑎2𝐶𝑂3
7.2 Percent yield of solid product
𝑃𝑒𝑟𝑐𝑒𝑛𝑡 𝑦𝑖𝑒𝑙𝑑 (%) =
𝑁𝑎𝑂𝐻 % 𝑦𝑖𝑒𝑙𝑑 =
2.93𝑔
× 100% = 𝟏𝟑𝟓%
2.1571𝑔
𝑁𝑎2𝑂 % 𝑦𝑖𝑒𝑙𝑑 =
2.93𝑔
× 100% = 𝟏𝟕𝟓%
1.6718𝑔
𝑁𝑎2𝐶𝑂3 % 𝑦𝑖𝑒𝑙𝑑 =
𝐴𝑐𝑡𝑢𝑎𝑙 𝑦𝑖𝑒𝑙𝑑
× 100%
𝑇ℎ𝑒𝑜𝑟𝑒𝑡𝑖𝑐𝑎𝑙 𝑦𝑖𝑒𝑙𝑑
2.93𝑔
× 100% = 𝟏𝟎𝟑%
2.8582𝑔
12
7.3 Percent error of the experiment
𝑃𝑒𝑟𝑐𝑒𝑛𝑡 𝑒𝑟𝑟𝑜𝑟 (%) =
|𝐸𝑥𝑝𝑒𝑟𝑖𝑚𝑒𝑛𝑡𝑎𝑙 𝑣𝑎𝑙𝑢𝑒 − 𝐴𝑐𝑐𝑒𝑝𝑡𝑒𝑑 𝑣𝑎𝑙𝑢𝑒|
× 100%
𝐴𝑐𝑐𝑒𝑝𝑡𝑒𝑑 𝑣𝑎𝑙𝑢𝑒
𝑁𝑎𝑂𝐻 𝑒𝑟𝑟𝑜𝑟(%) =
|2.93𝑔 − 2.1571𝑔|
× 100% = 𝟑𝟓. 𝟖𝟑%
2.1571𝑔
𝑁𝑎2𝑂 𝑒𝑟𝑟𝑜𝑟(%) =
|2.93𝑔 − 1.6718𝑔|
× 100% = 𝟕𝟏. 𝟎𝟏%
1.6718𝑔
𝑁𝑎𝑂𝐻 𝑒𝑟𝑟𝑜𝑟(%) =
|2.93𝑔 − 2.8582𝑔|
× 100% = 𝟐. 𝟓𝟏%
2.8582𝑔
13
8.0 Discussion
The overview of this experiment is about decomposition reaction of sodium
bicarbonate when heat is applied. Baking soda, also known as sodium bicarbonate, NaHCO3,
is a chemical that can decompose when heated. Sodium bicarbonate breaks down into three
components when temperatures exceed 176°F (80°C): sodium carbonate, Na2CO3, water,
H2O, and carbon dioxide, CO2. [Svenja Lohner, 2017] . Additionally, the molar mass is being
used to convert the calculation's unit.[Boundless.com, 2014] The main aim of this experiment
is to find out the decomposition reaction occurred during the experiment, calculate the percent
error and the percent yield of the experiment. In essence, the discussion will be mainly about
three possible reaction that could be occurred inside the crucible.
NaHCO3(s) → NaOH(s) + CO2(g) First possible reaction
2NaHCO3(s) → Na2O(s) +2CO2(g)+H2O Second possible reaction
In the first possible reaction, the heat decompostion of 1 mole of sodium bicarbonate
produced 1 mole of sodium hydroxide in the solid state and 1 mole of carbon dioxide in gas.
The theoretical value for the first reaction produces 2.1571 g of NaOH. From the set of data
collection, the percent yield is 135%. Meanwhile, in the second reaction 2 mole of sodium
bicarbonate produced 1 mole of solid sodium oxide as well as 1 mole of carbon dioxide in gas
state and 1 mole of water vapor. Data from the stoichiometric mass prediction, the theoretical
mass for the second rection is 1.6718g. Subsequently, the percent yield is 175%. Based on
the theory, first and second possible reaction is not the reaction occur since the mass of data
obtained are not close to the experimental value. Indeed, it is not the correct reaction because
the theoretical data gained from stoichiometric mass are slightly difference as the mass of
product gained after heating.
2NaHCO3(s) → Na2CO3(s) +CO2(g)+H2O Third possible reaction
Because the theoretical mass will be determined using the stoichiometry coefficient of the
mole value of the substance from the chemical equation. It is essential to balance the chemical
equation first. [Joseph Nijmeh, 2020] The balanced chemical equation for the third possible
reaction portrayed 2 mole of sodium bicarbonate will produce 1 mole of sodium carbonate in
the solid state along with 1 mole of carbon dioxide gas and 1 mole water vapor. From the set
data collection, the theoretical mass for substance Na2CO3 is 2.8582g. To be exact, this mass
the nearest one with the mass of product gained after heating. Along with that, this chemical
reaction has 102 percent yield. By this it simply means maximum amount of Na2CO3 will be
produced after the thermal breakdown on the substance was completed. After performing the
14
necessary stoichiometric calculation, this reaction obtained the closest data to the
experimental value. Thus, it is experimentally proven that the third reaction is the answer we
all are looking for.
Subsequently the experiment was followed by the calculation of error value that occurs
through out the experiment. The data documented in table 6.4 can provide a crystal clear
information needed to support our finding that has been discussed in the paragraphs above.
The percent error differs quite a lot between the substances. Na2CO3 with the least amount
of percent error, 2.51 percent followed by NaOH with 35.83 percent. Conversely, Na2O has
carry the largest percent of error which is 75.26 percent. Based on the data, we can concluded
the third reaction was confirmed to be the reaction for this experiment. Noted that since the
finding align with the early hypothesis, assuming the third possible reaction to be the chemical
reaction is certainly accepted.
15
9.0 Conclusion
For each potential reaction, the stoichiometry mass prediction is calculated. From the
decomposition of sodium bicarbonate in this experiment, it can be seen that the components
produced are solid, water and gas component in the presence of heat. As a result, the solid
product's mass lowers. Based on the finding, we find out that, the mass product of sodium
hydroxide is 2.1429 g NaOH, the mass product of sodium oxide is 1.6607 g Na20, and the
mass product of sodium carbonate is 2.8392 g NaCO3. It can be seen that, by using
stoichiometry, the amount or quantity of products or reactant can be obtained if one of the
values either reactant or product is provided. Based on the result obtained, reaction 3 is the
most correct reaction for this decomposition due to the fact that the stoichiometric mass of this
reaction is the nearest with the mass of sodium bicarbonate after heating.To summarise,
stoichiometry is a chemistry principle that determines the amount of reactant needed to make
a given amount of product, as well as the amount of product required for a given amount of
reactant to carry out the chemical reaction and measure the desired output. This experiment
was successful since it was able to acquire the best possible value.
10.0 Recommendation
During the conduct and conduction of a laboratory experiment, a few errors will occur.
To begin, this experiment requires mass readings of the crucible and sodium bicarbonate
as stated in the procedure. Thus, please tare the balance pan before weighing any mass
with it in order to obtain correct data.
Aside from that, it is suggested that the experiment be carried out in a small container,
such as a crucible. This is to prevent it from reacting with the air and forming a new
reaction. When the product is in gas form, stoichiometry is difficult to implement.
Last but not least, it is recommended to use oven because it will give high accuracy to
the mass readings due to its close space and there are no other sources of heat. Plus, it
already has its own timer.
16
11.0 References
[1]
Anne Marie Helmenstine. (2021). Mole Ratio: Definition and Examples. Thoughtco.
https://www.thoughtco.com/definition-of-mole-ratio-and-examples-605365
[2]
Bakerpedia. (2018). Baking Soda. Bakerpedia. https://bakerpedia.com/ingredients/baking-
soda/#
[3]
Boundless.com.(2014). Molar Mass. Lumen. https://courses.lumenlearning.com/boundless-
chemistry/chapter/molar-mass/
[4]
Boundless
Chemistry.
(2014). The
Law
of
Conservation
of
Mass.
Lumen.https://courses.lumenlearning.com/introchem/chapter/the-law-of-conservation-of-mass/
[5]
Erik
Gregersen.
(2021). law
of
definite proportions.
Britannica.
https://www.britannica.com/science/law-of-definite-proportions
[6]
Frederick
John.
(2018). Sodium Bicarbonate.
Encyclopedia.Com.
https://www.encyclopedia.com/science-and-technology/chemistry/compounds-and- elements/sodiumbicarbonate#D
[7]
Joseph Nijmeh. (2020). Stoichiometry and Balancing Reactions. Chem.Libretexts.Org, 16
August 2020.
[8]
https://chem.libretexts.org/Bookshelves/Inorganic_Chemistry/Supplemental_Modules_a
nd_Websites_(Inorganic_Chemistry)/Chemical_Reactions/Stoichiometry_and_Balancin g_Reactions
laney.edu. (2013). Experiment 13 - Thermal Decomposition of Sodium Bicarbonate. Cheli- Fossum.
https://laney.edu/cheli-fossum/wp-content/uploads/sites/210/2011/08/13-
Thermal-Decomp-
of-NaHCO3.pdf
[9]
Santa Monica College. (2021). 7: Mole Ratios and Reaction Stoichiometry (Experiment).
Chem.Libretexts.Org,
23
September
2021.
https://chem.libretexts.org/Ancillary_Materials/Laboratory_Experiments/Wet_Lab_Exp
eriments/General_Chemistry_Labs/Online_Chemistry_Lab_Manual/Chem_10_Experim
ents/07%3A_Mole_Ratios_and_Reaction_Stoichiometry_(Experiment)
[10]
Svenja Lohner. (2017). Vanishing Baking Soda, A decomposing science project. Science
Buddies. https://www.scientificamerican.com/article/vanishing-baking-soda/
17