Benzoic Acid PDF

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Theory of Benzoic Acid...

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Theory : Benzoic acid (C6H5COOH) is an organic molecule as it is an aromatic carboxylic compound. It’s chemical structure consists of a benzene (C6H6) and a carboxylic acid group (- COOH). It has hydrogen bonding between one hydrogen-oxygen molecule located in the carboxylic acid group.Benzoic acid is commonly used as a food preservative and is found in a white solid/crystalline form. The density of benzoic acid is 1.3g/cm3. The efficacy of benzoic acid depends on the pH levels as its pH level is lower than 4 therefore is suitable in foods with lower or the same pH levels. It can only remain as an acid in an acid environment as it is generally a weak acid in nature. It is obtained commercially through partial oxidation but can be naturally sourced through gum benzoin. As Benzoic acid is used as food preservative, it is able to prohibit enzyme growth due to its acidic nature and has antimicrobial properties. Enzymes and pathogenic bacteria tend to grow in areas with a pH level of 6.5-7 but don’t tend to strive well in acidic environments. Benzoic acid has a pKa of 4.20 and works by changing the internal pH of microbes and bacteria into an acidic state which prevents their survival and their growth. Benzoic acid Benzoic acid is composed of both a hydrophobic ( Benzene ring) and hydrophilic group (Carboxylic acid) . Benzoic acid is slightly soluble in water but is highly soluble in alcohols, ethers and benzene. This is due to Benzoic acid being a weak acid therefore partially dissociated in water. Though the water molecule is able to hydrogen bond with the carboxylic group but due the large nonpolar benzene ring it is unable to form hydrogen bonding but can only rely through Van Der Waals interactions.

+¿ ¿ −¿+H 3 O ¿ C6 H 5 COOH +H 2 O↔ C 6 H 5 CO O It is able to bind with alcohols and esters because benzoic acid depends on the basicity of the solution. As benzoic acid is poorly soluble in aqueous solutions, its salt sodium benzoate is used in drinks and solutions. As the lemonade mixture is combined with HCl, it produces a more acidic solution. This is to prepare the production of benzoic acid. Sodium benzoate reacts with hydrochloric acid by As benzoic acid is relatively insoluble in water. The newly formed product will contain chlorine in the In the first part of the experiment, the washing of lemonade through the separatory funnel helps separate the solute from the liquid organic solvents, as organic acids are soluble in organic solvents. It is

used to extract and retain the purity of the benzoic acid. As the lemonade solution is washed, it forms two layers of solvents: an aqueous layer which contains water and solute and an organic layer on top containing the dichloromethane and organic solvent. These layers are immiscible through the principle of “like dissolves like” as the polar solvents react with one another and non polar solvent with other nonpolar molecules. The organic layer is on the top as it has a lower density compared to the aqueous layer as it is in the bottom. With the help of a base(), Benzoic acid will undergo a reaction with .Through the separation of the organic layer and the aqueous layer by draining out the aqueous layer using the separatory funnel, it The solid substance that is obtained from the lemonade solution can be either benzoic acid or a mixture of a solid and benzoic acid. The product that is derived through evaporation and filtration can be determined of its purity through melting point ranges. Melting point range is the range of temperature in which a solid begins to start melting to the lowest temperature and to where the solid has been completely melted. As the melting points of the substance are similar, the melting point ranges have to be compared to other compounds as to the pure compound and the mixture between the unknown material and the known substance to see if there is an identical “mixed melting point”, thus meaning that it is the same substance. The theoretical melting point of pure benzoic acid is 122 ℃

Theory : Benzoic acid (C6H5COOH) is an organic molecule as it is an aromatic carboxylic compound. It’s chemical structure consists of a benzene (C6H6) and a carboxylic acid group (- COOH). (1) It has hydrogen bonding between one hydrogen-oxygen molecule located in the carboxylic acid group. (1) Benzoic acid is

commonly used as a food preservative and is found in a white solid/crystalline form. (1) The density of benzoic acid is 1.3g/cm3.The efficacy of benzoic acid depends on the pH levels as its pH level is lower than 4 therefore is suitable in foods with lower or the same pH levels. (2) It can only remain as an acid in an acid environment as it is generally a weak acid in nature. (2) It is obtained commercially through partial oxidation but can be naturally sourced through gum benzoin. (2)

As Benzoic acid is used as food preservative, it is able to prohibit enzyme growth due to its acidic nature and has antimicrobial properties. (3) Enzymes and pathogenic bacteria tend to grow in areas with a pH level of 6.5-7 but don’t tend to strive well in acidic environments. (3) Benzoic acid has a pKa of 4.20 and works by changing the internal pH of microbes and bacteria into an acidic state which prevents their survival and their growth. Benzoic acid is a yeast inhibitor and has antifungal properties (4). When ingested from fruits and vegetables, it is produced by bacteria found in the gut . (5) Benzoic acid is composed of both a hydrophobic (Benzene ring, C6H6) and hydrophilic group (Carboxylic acid, COOH) . (6) Benzoic acid is slightly soluble in water but is highly soluble in alcohols, ethers and benzene as most organic acids tend to be weak.. (6) This is due to Benzoic acid being a weak acid therefore partially dissociated in water. (6) It is also due to its resonance as the carboxyl group is an electron donating group decreasing the acidity whereas the benzene ring is an electron withdrawing group increasing the acidity.(7) Though the water molecule is able to hydrogen bond with the carboxylic group but due the large nonpolar benzene ring it is unable to form hydrogen bonding but can only rely through Van Der Waals interactions. (8)

+¿ ¿ −¿+H 3 O ¿ C6 H 5 COOH +H 2 O↔ C 6 H 5 CO O It is able to bind with alcohols and esters because benzoic acid depends on the basicity of the solution.(8) As benzoic acid is poorly soluble in aqueous solutions, its salt sodium benzoate is used in drinks and solutions. (9) Sodium Benzoate is a polar compound and has a negative charge and water is a polar compound therefore it is more soluble in water than benzoic acid, a nonpolar compound. (10)

As the lemonade mixture is combined with HCl, it produces a more acidic solution. This is to prepare the production of benzoic acid. Sodium benzoate is a weak base with the pka of 4.08 (11) and Hydrochloric acid, a strong acid with a pka of -6.3.(12) To transform sodium benzoate and benzoic acid, a strong acid will be needed in order to protonate it. When combined, they undergo an acid-base reaction as the hydrogen ions (H+) replaces the sodium ions (Na +) to form Benzoic acid allowing it to precipitate. (13) As the conjugate acids are weaker than HCl, the product side is more favoured. Using Diluted hydrochloric acid ensures that no strong reactions occur in the solution. (14)

In order to extract benzoic acid from lemonade, the liquid-liquid extraction of lemonade through the separatory funnel helps separate the solute from the liquid organic solvents, as organic acids are soluble in organic solvents. (15) It is used to extract and retain the purity of the benzoic acid. (15) As the lemonade solution is washed, it forms two layers of solvents: an aqueous layer which contains water and solute and an organic layer on top containing the dichloromethane and organic solvent. (15)The reactions between the layers form a homogeneous mixture between the organic layer and the aqueous layer. (15) These layers are immiscible through the principle of “like dissolves like '' as the polar solvents react with one another and non polar solvent with other nonpolar molecules. (16) The organic layer is on the top as it has a lower density compared to the aqueous layer as it is in the bottom.(17) As benzoic acid is non-polar and as well as dichloromethane, benzoic acid will remain in the organic layer.(18) This is due to the benzene ring in benzoic acid as it is non -polar thus allowing it to be more dissolved in a nonpolar solvent, dichloromethane. (18)Through the separation of the organic layer and the aqueous layer by draining out the aqueous layer using the separatory funnel it allows to isolate benzoic acid. (18) The method of evaporation in a hot water bath allows the remaining solution to evaporate from the layer, in this experiment, the organic layer. (19) This step is to ensure that no remaining solution from the ether layer is within benzoic acid , affecting its purity as it is more soluble in higher temperatures. Through gravity filtration, it allows the separation between the solid (precipitate) from the liquid. (20) The final product will be a solid substance (20). The weight/volume percentage concentration can be

found through as follows, as it is calculated by the mass of the solute (grams) over how many milliliters of solution. (21) This % yield enables determination of the concentration levels of benzoic acid within a lemonade drink. (21)

w /v % :

Mass of solute (g) ×100 % Volume of Solution(mL)

The solid substance that is obtained from the lemonade solution can be either benzoic acid or a mixture of a solid and benzoic acid (22) . The theoretical melting point of pure benzoic acid is 122℃ (23). The product that is derived through evaporation and filtration can be determined of its purity through melting point ranges. (22) Melting point range is the range of temperature in which a solid begins to start melting to the lowest temperature and to where the solid has been completely melted. (22) As the melting points of the substance are similar, the melting point ranges have to be compared to other compounds as to the pure compound and the mixture between the unknown material and the known substance to see if there is an identical “mixed melting point”, thus meaning that it is the same substance. (22)

Theory: 1. https://study.com/academy/lesson/benzoic-acid-structure-formula-uses.html :April 17, 2020 (Top part) 2. https://study.com/academy/lesson/benzoic-acid-structure-formula-uses.html :April

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(Middle part) 3. https://study.com/academy/lesson/benzoic-acid-structure-formula-uses.html :April (Bottom part) 4. https://www.sciencedirect.com/topics/agricultural-and-biological-sciences/benzoic-acid : April 20,

2020 (Top Part) 5. https://www.sciencedirect.com/topics/agricultural-and-biological-sciences/benzoic-acid : April 20, 2020 (Middle Part) 6. https://www.sciencedirect.com/topics/agricultural-and-biological-sciences/benzoic-acid : April 20, 2020 (Bottom Part) 7. https://www.msdsonline.com/2015/02/16/benzoic-acid-uses-and-safety/: April 25, 2020( Top part) 8. https://www.msdsonline.com/2015/02/16/benzoic-acid-uses-and-safety/: April 25, 2020( Bottom part) 9. https://aem.asm.org/content/70/8/4449: April 30, 2020 (Middle Part) 10. https://hmdb.ca/metabolites/HMDB0001870: May 01, 2020 (Bottom Part) 11. http://landing.carolina.com/Global/FileLib/dl-content/580104_ChemOfLife_AssessmentKey.pdf: April 29, 2020(Top Part)

12. http://landing.carolina.com/Global/FileLib/dl-content/580104_ChemOfLife_AssessmentKey.pdf : April 29,2020 (Middle Part) 13. http://landing.carolina.com/Global/FileLib/dl-content/580104_ChemOfLife_AssessmentKey.pdf :

April 29, 2020(Bottom Part) 14. http://www.ncert.nic.in/ncerts/l/lech202.pdf: April 29, 2020(Top Part) 15. https://sciencing.com/benzoic-acid-slightly-soluble-water-6392778.html:

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Part) 16. https://sciencing.com/benzoic-acid-slightly-soluble-water-6392778.html April 23,2020(Bottom Part) 17. https://www.sciencedirect.com/topics/chemistry/sodium-benzoate April 30,2020 (Top Part) 18. http://www.chem.ucla.edu/~bacher/Specialtopics/extraction.html April 24,2020(Top Part) 19. https://www.drugbank.ca/salts/DBSALT001289 May 01 , 2020 (Top Part) 20. https://courses.lumenlearning.com/boundless-chemistry/chapter/strength-of-acids/: May 05, 2020

(Top Part) 21. http://wwwchem.uwimona.edu.jm/lab_manuals/c1901exp8.html: April 28, 2020 (Top Part) 22. https://study.com/academy/lesson/hydrogen-chloride-vs-hydrochloric-acid.html: May 01, 2020 (Top Part) 23. https://chem.libretexts.org/Bookshelves/Ancillary_Materials/Demos%2C_Techniques %2C_and_Experiments/General_Lab_Techniques/Acid-Base_Extraction: April 30, 2020 (Top part) 24. https://chem.libretexts.org/Bookshelves/Ancillary_Materials/Demos%2C_Techniques %2C_and_Experiments/General_Lab_Techniques/Acid-Base_Extraction: April 30, 2020 ( Top part) 25. https://chem.libretexts.org/Bookshelves/Ancillary_Materials/Demos%2C_Techniques %2C_and_Experiments/General_Lab_Techniques/Acid-Base_Extraction: April 30, 2020 ( Middle part) 26. https://chem.libretexts.org/Bookshelves/Ancillary_Materials/Demos%2C_Techniques %2C_and_Experiments/General_Lab_Techniques/Acid-Base_Extraction: April 30, 2020 (Middle part) 27. https://chem.libretexts.org/Bookshelves/Ancillary_Materials/Demos%2C_Techniques %2C_and_Experiments/General_Lab_Techniques/Acid-Base_Extraction:

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( Bottom part) 28. https://chem.libretexts.org/Bookshelves/Organic_Chemistry/Book %3A_How_to_be_a_Successful_Organic_Chemist_(Sandtorv)/02%3A_COMMON_ORGANIC_ CHEMISTRY_LABORATORY_TECHNIQUES/2.03%3A_LIQUID-LIQUID_EXTRACTION: April 28, 2020(Top Part) 29. http://www.chem.ucla.edu/~bacher/Specialtopics/extraction.html: April 26, 2020 (Top Part) 30. http://www.chem.ucla.edu/~bacher/Specialtopics/extraction.html: April 26, 2020 (Middle Part) 31. http://www.chem.ucla.edu/~bacher/Specialtopics/extraction.html:April 26, 2020 (Bottom Part) 32. https://analyticalscience.wiley.com/do/10.1002/gitlab.894: May 01, 2020(Top Part) 33. https://orgchemboulder.com/Technique/Procedures/Filtration/Filtration.shtml: May 01, 2020 (Top

Part) 34. https://orgchemboulder.com/Technique/Procedures/Filtration/Filtration.shtml: April 30, 2020 (Bottom Part) 35. https://sciencing.com/calculate-wv-weight-volume-5092442.html: May 04, 2020 (Top Part) 36. https://sciencing.com/calculate-wv-weight-volume-5092442.html: May 04, 2020 (Bottom Part) 37. https://chemistry.sites.clemson.edu/organic/Labs/2270Docs/MeltingPoint.pdf: April 27, 2020 (Top Part) 38. https://pubchem.ncbi.nlm.nih.gov/compound/Benzoic-acid: April 27, 2020 (Top Part) 39. https://chemistry.sites.clemson.edu/organic/Labs/2270Docs/MeltingPoint.pdf: April 27, 2020 (Middle Part) 40. https://chemistry.sites.clemson.edu/organic/Labs/2270Docs/MeltingPoint.pdf: April 27, 2020 (Middle Part) 41. https://chemistry.sites.clemson.edu/organic/Labs/2270Docs/MeltingPoint.pdf: April 27, 2020 (Bottom Part)

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