CHEM 121LGeneral Chemistry Laborato

CHEM 121L

General Chemistry Laboratory
Revision 3.1



The Synthesis of Sodium Bicarbonate


• Learn about the element Sodium and some of its compounds.
• Learn about Bicarbonates.
• Learn about chemical stoichiometry and the theoretical yield of a Reaction.


In this laboratory exercise we will synthesize Sodium Bicarbonate (NaHCO3) via an old industrial process known as the Solvay Process. This industrial method for the production of

Sodium Bicarbonate was developed by Ernest Solvay in the 1860’s. The Sodium Bicarbonate produced via this process is then converted to the commercially important chemical Sodium Carbonate; also known as Soda Ash (Na2CO3) or Washing Soda (Na2CO3•10H2O).

2 NaHCO3(s) Na2CO3(s) + CO2(g) + H2O(g)


By 1890, most of the Soda Ash produced worldwide was produced as a result of the Solvay Process. Currently, three-quarters of the worldwide production of Soda Ash is via the Solvay Process.

Ernest Solvay (http://en.wikipedia.org/wiki/File:Ernest_Solvay.jpg)

























Solvay Plant, Solvay New York (~1917) (http://en.wikipedia.org/wiki/File:SolvayPlant-NY-ErieCanal.jpg)

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Sodium Bicarbonate is one of a very many Sodium salts that are ubiquitous in our daily lives; from the Table Salt we use on our food to the Soaps we use for cleaning. Although compounds of Sodium are less abundant in nature than those of Potassium, Common Salt (Sodium Chloride, or NaCl) is such a readily available precursor that Sodium compounds are less expensive to produce than Potassium compounds and, as a result, are more widely used.

The uses of the salts of Sodium are extensive. A few examples are:

Sodium Chloride (NaCl)

Used, along with 0.01% KI, as Table Salt.

Electrolyzed in the Clor-Alkali Process to obtain other industrially important reagents.

2 NaCl(aq) + 2 H2O 2 NaOH(aq) + H2(g) + Cl2(g)

Reacted with Sulfuric Acid, H2SO4, to form Sodium Sulfate and Hydrogen Chloride; Sodium sulfate is important in the paper industry and HCl is essential in steel, plastics, textiles, and food production.

2 NaCl(s) + H2SO4(aq) Na2SO4(aq) + 2 HCl(aq)

Sodium Hydroxide (NaOH)

Used in formation of bleaching solutions:

2 NaOH(aq) + Cl2(g) NaClO(aq) + NaCl(aq) + H2O

Sodium Carbonate (Na2CO3)

Used in the production of glass, soap, paper and other industrially important chemicals. Also used in detergents as a substitute for phosphates.

Production of Soda Ash has some interesting history.

During the Middle Ages, the glass factories of France and Bohemia were dependent on Soda, imported by Arabs from the natural deposits in desert places of Asia Minor, or on barilla from Spain, which consisted of Soda from the ashes of marine plants. Shortly before the French Revolution, after England had cut France off from here barilla supply, the French Academy of Science offered a prize of 2,400 livres for a method of preparing Soda from salt. The problem was solved by Nicolas Leblanc, the physician to the Duke of Orleans. In the Leblanc process, salt was treated with concentrated sulfuric acid:

2 NaCl(s) + H2SO4(aq) Na2SO4(aq) + 2 HCl(aq)

The sodium sulfate, heated with limestone and coke, was converted into the carbonate:

Na2SO4(s) + 2 C(s) Na2S(s) + 2 CO2
Na2S(s) + CaCO3(s) CaS(s) + Na2CO3(s)

which was leached out from the insoluble calcium sulfide with water.

The French Revolution was fatal to the hopes of Leblanc. The Duke of Orleans was guillotined, and Leblanc's daughter fell ill and died. Leblanc committed suicide. The prize was never awarded. During the 75 years that followed, his process grew into a great industry until it was replaced by the more economical Solvay Process.


General Chemistry by John Arrend Timm

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In this laboratory we will synthesize Sodium Bicarbonate (NaHCO3), more properly Sodium Hydrogen Carbonate, by the Solvay Process. Dry ice (solid CO2) is added to a saturated solution of Sodium Chloride (Brine) and concentrated aqueous Ammonia:

NaCl(aq) + NH3(aq) + CO2(s) + H2O NH4Cl(aq) + NaHCO3(s)
(Eq. 1)

The Dry Ice, in addition to serving as a reagent, also provides a means of cooling the reaction mixture. This is important because both the Ammonium Chloride (NH4Cl) and Sodium Bicarbonate are soluble at room temperatures. However, at much lower temperatures, the Sodium Bicarbonate is much less soluble than Ammonium Chloride and can be fractionally crystallized out of solution.

One problem that occurs with the Solvay Process is a side reaction produces significant amounts of Ammonium Bicarbonate(NH4HCO3). However, this can be removed by simply heating the solid product:

NH4HCO3(s) NH3(g) + H2O(g) + CO2(g) (Eq. 2)

The products of the resulting reaction are all gaseous and so are removed from the desired Sodium Bicarbonate.

Industrially, the success of the Solvay Process depends on the recovery of the Ammonia which remains in solution in the form of Ammonium Chloride. If the solution is treated with Milk of Lime (Ca(OH)2) the Ammonia gas is released and can be recovered.

Ca(OH)2(aq) + 2 NH4Cl(aq) 2 NH3(g) + 2 H2O + CaCl2(aq)
(Eq. 3)

It should be noted that the production of Sodium Bicarbonate in the United States is no longer economically feasible via the Solvay Process. Most Soda Ash in the United States is obtained by mining the mineral Trona, Na2CO3•NaHCO3•H2O, large deposits of which can be found near the Green River in Wyoming. Hence, the Solvay Process is fading into history in this country.



The Mineral Trona (http://en.wikipedia.org/wiki/File:Trona%28small%29.jpg)

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Pre-Lab Questions

1. Assuming we start with 10g of NaCl, how many grams of Sodium Bicarbonate are expected to be produced in this process?

2. Assuming we start with 10g of NaCl, how many grams of Ammonium Chloride are expected to be produced in this process?

3. What is the Solubility of Sodium Bicarbonate and Ammonium Chloride in Water at Room Temperature? (Internet search required.)

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Procedure

1. Set-up a Buchner Funnel with aspiration system. The final product will have to be filtered from solution quickly, before it has a chance to warm up.

2. Weight out 15g of NaCl and transfer it to a 250mL Erlenmeyer flask fitted with a solid stopper.

3. In the fume hood, add 50mL of conc. aqueous Ammonia to the flask containing the NaCl. Stopper the flask and keep it in the hood. Swirl and shake the flask for 15 minutes to saturate the solution with NaCl. Some of the solid NaCl should remain.

4. Allow the solid to settle, then decant the saturated Ammonia/NaCl solution into a 250mL beaker. Keep this in the fume hood.

5. Fill a 150mL beaker half full with crushed Dry Ice. This represents about 60-70g CO2. Do not handle the Dry Ice directly.

6. Over a 15 minute period, in the fume hood, add the Dry Ice in small portions to the Ammonia/NaCl solution. Stir the mixture with a glass stiring rod throughout the additions. Do not allow the solution to freeze. Solid Sodium and Ammonium bicaronate should begin to form near the end of the additions.

NaCl(aq) + NH3(aq) + CO2(s) + H2O

NH4Cl(aq) + NaHCO3(s)

7. Quickly filter the mixture before the temperature of the solution has a chance to rise about 0oC. Allow the suction filtration to continue for several minutes.

8. In the fume hood, place the solid mixture of bicarbonates in a watch glass and place the watch glass over a beaker of boiling water. Heat for 10-15 minutes.

NH4HCO3(s) NH3(g) + H2O(g) + CO2(g)

9. After the heating, cool the pure Sodium bicarbonate and weigh the product.

10. Obtain a 3 dram vial and submit a sample of your product. Label the vial with the following information:

Name(s)

Name of Compound Formula of Compound Date
Weight of Product

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11. As a simple test, to confirm that Sodium bicarbonate has been produced, instead of merely recrystallizing the Sodium chloride, place a small amount of your product in a test tube. Do the same with a small amount of the NaCl reagent. Add 5-6 drops of 3M HCl. Record your observations.

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Data Analysis

1. Assuming 10g of the 15g of NaCl used dissolves in the initial conc. Ammonia solution, what is the Theoretical Yield of Sodium Bicarbonate?

2. Calculate the Percentage Yield of Sodium Bicarbonate.

3. Comment on your Sources of Loss.

4. What chemical reactions are occuring when Sodium Bicarbonate is treated with 3M Hydrochloric Acid?

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Post Lab Questions

1. Bicarbonate, HCO3-(aq), is an example of an amphoteric species; i.e., will behave as both an acid and a base. Write a chemical equation for the reaction of Bicarbonate Ion with Hydrochloric Acid. Write a chemical equation for the reaction of Bicarbonate Ion with aqueous Sodium Hydroxide.

2. Sodium Bicarbonate can also be produced by bubbling CO2 gas through concentrated Sodium Hydroxide solutions. Water is a byproduct of this reaction. Write a balanced chemical equation for this method of synthesis of Sodium Bicarbonate.

3. Suppose I expect a loss of 75% when producing Sodium Bicarbonate via the Solvay Process. How many grams of Sodium Chloride must I start with if I want to produce 100g of Sodium Bicarbonate?

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Addendum

Properties of Hydrates


It should be noted that Washing Soda (Na2CO3•10H2O) occurs as a Hydrate. Hydrates are salts that crystallize from a water solution and contain weakly bound water molecules. For example, Ferric Chloride, FeCl3, crystallizes with six water molecules weakly bound to the Fe3+ ion in an octahedral arrangement:














This is denoted as FeCl3•6H2O and is referred to as Ferric Chloride Hexahydrate.

Note the unusual method for writing the chemical formula of this compound. A hydrate is an addition compound; a compound that contains two or more simpler compounds. In the above example, the simpler compounds are FeCl3 and H2O, which combine in a rat

النتائج (العربية) 1:

تشم ل 121مختبر الكيمياء العامةالتنقيح 3.1توليف بيكربونات الصوديوم• التعرف على عنصر الصوديوم وبعض مركباته. • التعرف على بيكربونات. • التعرف على ستويتشيوميتري الكيميائية والمردود النظري لفعل. في هذا التمرين المختبر سوف التوليف بين بيكربونات الصوديوم (NaHCO3) عن طريق عملية صناعية قديمة المعروفة باسم عملية سولفاي. هذا الأسلوب الصناعي لإنتاجبيكربونات الصوديوم طوره إرنست سولفاي في 1860's. ثم يتم تحويل بيكربونات الصوديوم المنتجة عن طريق هذه العملية إلى كربونات الصوديوم الكيميائية الهامة تجارياً؛ يعرف أيضا باسم رماد الصودا (Na2CO3) أو صودا الغسيل (Na2CO3•10H2O).2 NaHCO3(s) Na2CO3(s) + CO2(g) + H2O(g)قبل عام 1890، تم إنتاج أكثر من رماد الصودا المنتجة في جميع أنحاء العالم نتيجة لعملية سولفاي. وحاليا ثلاثة أرباع الإنتاج العالمي من رماد الصودا عن طريق عملية سولفاي.إرنست سولفاي (http://en.wikipedia.org/wiki/File:Ernest_Solvay.jpg) مصنع سولفاي، نيويورك سولفاي (~ 1917) (http://en.wikipedia.org/wiki/File:SolvayPlant--نيويورك--ErieCanal.jpg) ف أ ه ز | 2بيكربونات الصوديوم هي واحدة أملاح الصوديوم كثيرة جداً موجودة في كل مكان في حياتنا اليومية؛ من ملح الطعام نستخدمها في غذائنا للصابون نستخدمها لتنظيف. على الرغم من أن مركبات الصوديوم أقل وفرة في الطبيعة من تلك من البوتاسيوم، المشتركة الملح (كلوريد الصوديوم أو كلوريد الصوديوم) هو هذه سلائف متاحة بسهولة الصوديوم تلك المركبات هي أقل تكلفة لإنتاج مركبات البوتاسيوم، ونتيجة لذلك يتم استخدامها على نطاق واسع.The uses of the salts of Sodium are extensive. A few examples are:Sodium Chloride (NaCl)Used, along with 0.01% KI, as Table Salt.Electrolyzed in the Clor-Alkali Process to obtain other industrially important reagents.2 NaCl(aq) + 2 H2O 2 NaOH(aq) + H2(g) + Cl2(g)Reacted with Sulfuric Acid, H2SO4, to form Sodium Sulfate and Hydrogen Chloride; Sodium sulfate is important in the paper industry and HCl is essential in steel, plastics, textiles, and food production.2 NaCl(s) + H2SO4(aq) Na2SO4(aq) + 2 HCl(aq)Sodium Hydroxide (NaOH)Used in formation of bleaching solutions:2 NaOH(aq) + Cl2(g) NaClO(aq) + NaCl(aq) + H2OSodium Carbonate (Na2CO3)Used in the production of glass, soap, paper and other industrially important chemicals. Also used in detergents as a substitute for phosphates.Production of Soda Ash has some interesting history.During the Middle Ages, the glass factories of France and Bohemia were dependent on Soda, imported by Arabs from the natural deposits in desert places of Asia Minor, or on barilla from Spain, which consisted of Soda from the ashes of marine plants. Shortly before the French Revolution, after England had cut France off from here barilla supply, the French Academy of Science offered a prize of 2,400 livres for a method of preparing Soda from salt. The problem was solved by Nicolas Leblanc, the physician to the Duke of Orleans. In the Leblanc process, salt was treated with concentrated sulfuric acid:2 NaCl(s) + H2SO4(aq) Na2SO4(aq) + 2 HCl(aq)The sodium sulfate, heated with limestone and coke, was converted into the carbonate:Na2SO4(s) + 2 C(s) Na2S(s) + 2 CO2Na2S(s) + CaCO3(s) CaS(s) + Na2CO3(s)which was leached out from the insoluble calcium sulfide with water.The French Revolution was fatal to the hopes of Leblanc. The Duke of Orleans was guillotined, and Leblanc's daughter fell ill and died. Leblanc committed suicide. The prize was never awarded. During the 75 years that followed, his process grew into a great industry until it was replaced by the more economical Solvay Process. General Chemistry by John Arrend Timm P a g e | 3In this laboratory we will synthesize Sodium Bicarbonate (NaHCO3), more properly Sodium Hydrogen Carbonate, by the Solvay Process. Dry ice (solid CO2) is added to a saturated solution of Sodium Chloride (Brine) and concentrated aqueous Ammonia:NaCl(aq) + NH3(aq) + CO2(s) + H2O NH4Cl(aq) + NaHCO3(s)(Eq. 1)The Dry Ice, in addition to serving as a reagent, also provides a means of cooling the reaction mixture. This is important because both the Ammonium Chloride (NH4Cl) and Sodium Bicarbonate are soluble at room temperatures. However, at much lower temperatures, the Sodium Bicarbonate is much less soluble than Ammonium Chloride and can be fractionally crystallized out of solution.One problem that occurs with the Solvay Process is a side reaction produces significant amounts of Ammonium Bicarbonate(NH4HCO3). However, this can be removed by simply heating the solid product:NH4HCO3(s) NH3(g) + H2O(g) + CO2(g) (Eq. 2)The products of the resulting reaction are all gaseous and so are removed from the desired Sodium Bicarbonate.Industrially, the success of the Solvay Process depends on the recovery of the Ammonia which remains in solution in the form of Ammonium Chloride. If the solution is treated with Milk of Lime (Ca(OH)2) the Ammonia gas is released and can be recovered.Ca(OH)2(aq) + 2 NH4Cl(aq) 2 NH3(g) + 2 H2O + CaCl2(aq)(Eq. 3)It should be noted that the production of Sodium Bicarbonate in the United States is no longer economically feasible via the Solvay Process. Most Soda Ash in the United States is obtained by mining the mineral Trona, Na2CO3•NaHCO3•H2O, large deposits of which can be found near the Green River in Wyoming. Hence, the Solvay Process is fading into history in this country.The Mineral Trona (http://en.wikipedia.org/wiki/File:Trona%28small%29.jpg) P a g e | 4Pre-Lab Questions1. Assuming we start with 10g of NaCl, how many grams of Sodium Bicarbonate are expected to be produced in this process? 2. Assuming we start with 10g of NaCl, how many grams of Ammonium Chloride are expected to be produced in this process? 3. What is the Solubility of Sodium Bicarbonate and Ammonium Chloride in Water at Room Temperature? (Internet search required.) P a g e | 5Procedure1. Set-up a Buchner Funnel with aspiration system. The final product will have to be filtered from solution quickly, before it has a chance to warm up. 2. Weight out 15g of NaCl and transfer it to a 250mL Erlenmeyer flask fitted with a solid stopper. 3. In the fume hood, add 50mL of conc. aqueous Ammonia to the flask containing the NaCl. Stopper the flask and keep it in the hood. Swirl and shake the flask for 15 minutes to saturate the solution with NaCl. Some of the solid NaCl should remain. 4. Allow the solid to settle, then decant the saturated Ammonia/NaCl solution into a 250mL beaker. Keep this in the fume hood. 5. Fill a 150mL beaker half full with crushed Dry Ice. This represents about 60-70g CO2. Do not handle the Dry Ice directly. 6. Over a 15 minute period, in the fume hood, add the Dry Ice in small portions to the Ammonia/NaCl solution. Stir the mixture with a glass stiring rod throughout the additions. Do not allow the solution to freeze. Solid Sodium and Ammonium bicaronate should begin to form near the end of the additions. NaCl(aq) + NH3(aq) + CO2(s) + H2ONH4Cl(aq) + NaHCO3(s)7. Quickly filter the mixture before the temperature of the solution has a chance to rise about 0oC. Allow the suction filtration to continue for several minutes. 8. In the fume hood, place the solid mixture of bicarbonates in a watch glass and place the watch glass over a beaker of boiling water. Heat for 10-15 minutes. NH4HCO3(s) NH3(g) + H2O(g) + CO2(g)9. After the heating, cool the pure Sodium bicarbonate and weigh the product. 10. Obtain a 3 dram vial and submit a sample of your product. Label the vial with the following information: Name(s) Name of Compound Formula of Compound Date Weight of Product P a g e | 611. As a simple test, to confirm that Sodium bicarbonate has been produced, instead of merely recrystallizing the Sodium chloride, place a small amount of your product in a test tube. Do the same with a small amount of the NaCl reagent. Add 5-6 drops of 3M HCl. Record your observations. P a g e | 7Data Analysis1. Assuming 10g of the 15g of NaCl used dissolves in the initial conc. Ammonia solution, what is the Theoretical Yield of Sodium Bicarbonate? 2. Calculate the Percentage Yield of Sodium Bicarbonate. 3. Comment on your Sources of Loss. 4. What chemical reactions are occuring when Sodium Bicarbonate is treated with 3M Hydrochloric Acid? P a g e | 8Post Lab Questions1. Bicarbonate, HCO3-(aq), is an example of an amphoteric species; i.e., will behave as both an acid and a base. Write a chemical equation for the reaction of Bicarbonate Ion with Hydrochloric Acid. Write a chemical equation for the reaction of Bicarbonate Ion with aqueous Sodium Hydroxide. 2. Sodium Bicarbonate can also be produced by bubbling CO2 gas through concentrated Sodium Hydroxide solutions. Water is a byproduct of this reaction. Write a balanced chemical equation for this method of synthesis of Sodium Bicarbonate. 3. Suppose I expect a loss of 75% when producing Sodium Bicarbonate via the Solvay Process. How many grams of Sodium Chloride must I start with if I want to produce 100g of Sodium Bicarbonate? P a g e | 9AddendumProperties of HydratesIt should be noted that Washing Soda (Na2CO3•10H2O) occurs as a Hydrate. Hydrates are salts that crystallize from a water solution and contain weakly bound water molecules. For example, Ferric Chloride, FeCl3, crystallizes with six water molecules weakly bound to the Fe3+ ion in an octahedral arrangement:This is denoted as FeCl3•6H2O and is referred to as Ferric Chloride Hexahydrate.Note the unusual method for writing the chemical formula of this compound. A hydrate is an addition compound; a compound that contains two or more simpler compounds. In the above example, the simpler compounds are FeCl3 and H2O, which combine in a rat

النتائج (العربية) 3:

Chem 121l


مختبر الكيمياء العامة التنقيح 3-1






تأليف بيكربونات الصوديوم • معرفة عنصر الصوديوم و بعض المركبات.
• معرفة البيكربونات.
• معرفة Stoichiometry الكيميائية وحاصل النظرية من ردود فعل.


في هذه العملية المختبرية سوف توليف بيكربونات الصوديوم (nahco3) عن طريق الصناعية القديمة عملية تعرف باسم عملية سولفاي.هذه الطريقة الصناعية من أجل إنتاج

بيكربونات الصوديوم وضعتها إرنست سولفاي في 1860. بيكربونات الصوديوم المنتجة عبر هذه العملية ثم تحويلها إلى الأهمية التجارية الكيميائية كربونات الصوديوم.