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A student recrystallized some impure benzoic acid and isolated it by filtration. He scraped the purified benzoic acid off the filter paper after it had dried and took the melting point as a test for p?
The student's approach to isolating and testing the purity of benzoic acid is appropriate, as recrystallization is a common method for purifying solids. After scraping the dried benzoic acid from the filter paper, taking the melting point is a valid method for assessing purity; pure substances have a sharp melting point range, while impurities typically depress and broaden this range. If the observed melting point of the recrystallized benzoic acid closely matches the literature value for pure benzoic acid, it suggests successful purification. Conversely, a significant deviation would indicate the presence of impurities.
Why 4 hydroxy benzoic acid is less acidic than 2 hydroxy benzoic acid?
as because in 2-hydroxy benzoic acid, there is a possibility of H-bonding which makes the dissociated ion stable and will not combine with H+ ion leaving it free, while it is not so in case of 4-hydroxy benzoic acid.
Given a pure sample that is either pure benzoic acid or 2-naphthol give a procedure that can be used to determine the identity of the sample?
Lets see. Add neutral ferric chloride to the sample solution. A coloured solution is obtained if it is 2-naphthol (most phenols give colour with neutral ferric chloride solution). Add sodium bicarbonate to the sample solution. Carboxylic acids evolve carbon dioxide gas. Phenols (except strong ones like picric acid) does not. Both 2-naphthol and benzoic acid will evolve hydrogen when treated with metallic sodium (test not advisable to do) and NaOH. Phenols form pleasent smelling esters when treated with carboxylic acids where as benzoic acid will be fruity odour with alcohols or phenols. Both benzoic acid and 2-naphthol melts about 1220C whereas the boiling point of benzoic acid is 2490C and that of 2-naphthol is 2850C.
How pure benzoic acid may be separated form a solution of sand and benzoic acid?
To separate benzoic acid from a solution of sand and benzoic acid, you can use solvent extraction. Benzoic acid is soluble in organic solvents like diethyl ether, while sand is not. By adding diethyl ether to the solution, the benzoic acid will dissolve in the ether, allowing you to separate it from the sand by decanting or filtration. Then, evaporate the diethyl ether to recover the pure benzoic acid.
Why is it necessary to filter the benzoic acid solution while hot?
Filtering the benzoic acid solution while hot helps to keep the compound in solution as it cools, preventing it from crystallizing and clogging the filter paper. This ensures that all impurities are removed from the solution before it solidifies.
Who will melt earlier benzoic acid or sodium chloride?
sodium chloride melt earlier because it has low freezing point
What did you observe while benzic acid-salt mixture is melting?
When a benzoic acid-salt mixture melts, you may observe the formation of a clear or slightly colored liquid. The melting point may be lower compared to the individual components, indicating a eutectic mixture. Any impurities present in the mixture may affect the melting behavior and appearance of the molten material.
What would happen to the melting point of pure benzoic acid if 2-naphthol was mixed in?
The literature value of the melting point of pure benzoic acid is about 122.4 degrees Celsius, while the literature value of the melting point of pure 2-naphthol is close at 122 degrees Celsius. Nevertheless, the melting point of the benzoic acid should be depressed (go down) compared to the literature value if you were to add 2-naphthol because the sample you were testing would then be impure, even if that impurity does have a similar melting point. Also, the range over which the sample melts should get larger as well. Instead of melting within a degree or less, it may melt over the course of several degrees. So I just tested this in lab, and I can't promise that this is 50/50, but my melting point for 2-naphthol with Benzoic acid is 104.1-106.0 degrees Celsius This is a very basic answer, and the trend is true. However, with my organic chemistry professor, this answer would be followed by a blank look and "Why?" The best way to think of this is to look at the chemical structure of Benzoic Acid and 2-naphthol separate. Go ahead and Google it on a new tab. Now look at the molecule of the two together. And think: "What does the composite molecule have that the two alone don't?" Give up? Electronegativity. The more electronegative a molecule is the greater its reactivity. As in the compound molecule will melt easier than the two 'pure' substances.
Why paraffin oil used in instrument while knowing melting point of benzoic acid?
Paraffin oil is used in instruments as a lubricant due to its low viscosity and ability to reduce friction between moving parts. Although benzoic acid has a higher melting point compared to paraffin oil, it is not commonly used as a lubricant in instruments due to its acidic nature and potential reactivity with other materials.
Does benzoic acid dissolve in ligroin?
yes it does with heat, although it might take a super long time when heat up.
Why 4 hydroxy benzoic acid is less acidic than 2 hydroxy benzoic acid?
as because in 2-hydroxy benzoic acid, there is a possibility of H-bonding which makes the dissociated ion stable and will not combine with H+ ion leaving it free, while it is not so in case of 4-hydroxy benzoic acid.
Why is it necessary to filter the benzoic acid while hot?
because it will form solid when cool
Given a pure sample that is either pure benzoic acid or 2-naphthol give a procedure that can be used to determine the identity of the sample?
Lets see. Add neutral ferric chloride to the sample solution. A coloured solution is obtained if it is 2-naphthol (most phenols give colour with neutral ferric chloride solution). Add sodium bicarbonate to the sample solution. Carboxylic acids evolve carbon dioxide gas. Phenols (except strong ones like picric acid) does not. Both 2-naphthol and benzoic acid will evolve hydrogen when treated with metallic sodium (test not advisable to do) and NaOH. Phenols form pleasent smelling esters when treated with carboxylic acids where as benzoic acid will be fruity odour with alcohols or phenols. Both benzoic acid and 2-naphthol melts about 1220C whereas the boiling point of benzoic acid is 2490C and that of 2-naphthol is 2850C.
How pure benzoic acid may be separated form a solution of sand and benzoic acid?
To separate benzoic acid from a solution of sand and benzoic acid, you can use solvent extraction. Benzoic acid is soluble in organic solvents like diethyl ether, while sand is not. By adding diethyl ether to the solution, the benzoic acid will dissolve in the ether, allowing you to separate it from the sand by decanting or filtration. Then, evaporate the diethyl ether to recover the pure benzoic acid.
Is benzoic acid or sucrose more soluble in water?
Sucrose is more soluble in water than benzoic acid. Sucrose is a polar molecule that can form hydrogen bonds with water molecules, increasing its solubility. Benzoic acid, while also polar, has a benzene ring which reduces its ability to form hydrogen bonds with water, making it less soluble.
What are the chemical tests to distinguish between benzaldehyde and benzoic acid?
One way to distinguish between benzaldehyde and benzoic acid is by performing a solubility test. Benzaldehyde is soluble in organic solvents, while benzoic acid is soluble in water. Another test is to add aqueous sodium bicarbonate: benzoic acid will effervesce as carbon dioxide gas is produced, whereas benzaldehyde will not show any reaction. Additionally, benzoic acid will give a characteristic white precipitate when treated with acidified potassium permanganate solution, while benzaldehyde will not react with this reagent.
Does benzoic acid have an odor?
Acetic acid is an aliphatic (fatty) acid and a liquid while benzoic acid is an aromatic acid which exists in solid state.
