Ultimate Organic Chemistry Quiz

1. Acetone can be tested by iodoform.

True

False

Acetone can be tested by iodoform because when acetone reacts with iodine and sodium hydroxide, it forms a yellow precipitate of iodoform. This reaction is a characteristic test for the presence of acetone. Therefore, the statement "Acetone can be tested by iodoform" is true.

Explanation

Acetone can be tested by iodoform because when acetone reacts with iodine and sodium hydroxide, it forms a yellow precipitate of iodoform. This reaction is a characteristic test for the presence of acetone. Therefore, the statement "Acetone can be tested by iodoform" is true.

2. Acetone can be tested by iodoform test.

True

False

Acetone can be tested by the iodoform test because it contains a methyl ketone group. The iodoform test is used to detect the presence of methyl ketones, such as acetone, by reacting them with iodine and a base. This reaction produces a yellow precipitate of iodoform, which confirms the presence of acetone. Therefore, the given statement is true.

Explanation

Acetone can be tested by the iodoform test because it contains a methyl ketone group. The iodoform test is used to detect the presence of methyl ketones, such as acetone, by reacting them with iodine and a base. This reaction produces a yellow precipitate of iodoform, which confirms the presence of acetone. Therefore, the given statement is true.

3. The Vigreux column is a fractionating column that allows the reasonable separation of compounds with a boiling point difference of 30-40° C.

True

False

The Vigreux column is a type of fractionating column that is designed to improve the separation of compounds with a small boiling point difference. It consists of a series of indentations or "baffles" along the length of the column, which increases the surface area available for vaporization and condensation. This increased surface area allows for more efficient separation of compounds with a boiling point difference of 30-40°C. Therefore, the statement that the Vigreux column allows reasonable separation of compounds with a boiling point difference of 30-40°C is true.

Explanation

The Vigreux column is a type of fractionating column that is designed to improve the separation of compounds with a small boiling point difference. It consists of a series of indentations or "baffles" along the length of the column, which increases the surface area available for vaporization and condensation. This increased surface area allows for more efficient separation of compounds with a boiling point difference of 30-40°C. Therefore, the statement that the Vigreux column allows reasonable separation of compounds with a boiling point difference of 30-40°C is true.

4. Chloral hydrate can form two H-bonds but chloral can not .

True

False

Chloral hydrate is a compound that contains a hydroxyl group (-OH) attached to the chloral molecule. This hydroxyl group can form two hydrogen bonds with other molecules or functional groups. On the other hand, chloral does not have a hydroxyl group and therefore cannot form hydrogen bonds. Hence, the statement that chloral hydrate can form two hydrogen bonds while chloral cannot is true.

Explanation

Chloral hydrate is a compound that contains a hydroxyl group (-OH) attached to the chloral molecule. This hydroxyl group can form two hydrogen bonds with other molecules or functional groups. On the other hand, chloral does not have a hydroxyl group and therefore cannot form hydrogen bonds. Hence, the statement that chloral hydrate can form two hydrogen bonds while chloral cannot is true.

5. What happens to the boiling point of a liquid when a more volatile solute is added to it?

Decrease

Increase

Doesn't affect

The effect is according to the condition.

When a more volatile solute is added to a pure liquid, it decreases the boiling point (BP) of the liquid. This is because the solute molecules disrupt the attractive forces between the liquid molecules, making it easier for the liquid to vaporize and reach its boiling point. As a result, the BP of the pure liquid decreases.

Explanation

When a more volatile solute is added to a pure liquid, it decreases the boiling point (BP) of the liquid. This is because the solute molecules disrupt the attractive forces between the liquid molecules, making it easier for the liquid to vaporize and reach its boiling point. As a result, the BP of the pure liquid decreases.

6. Electron-withdrawing groups in the para position decrease the acidity and nucleophilicity of phenol.

True

False

Electron-withdrawing groups in the para position do not decrease the acidity and nucleophilicity of phenol. In fact, these groups increase the acidity of phenol by stabilizing the negative charge on the oxygen atom. Additionally, electron-withdrawing groups also enhance the nucleophilicity of phenol by making the oxygen atom more electron-deficient. Therefore, the given statement is false.

Explanation

Electron-withdrawing groups in the para position do not decrease the acidity and nucleophilicity of phenol. In fact, these groups increase the acidity of phenol by stabilizing the negative charge on the oxygen atom. Additionally, electron-withdrawing groups also enhance the nucleophilicity of phenol by making the oxygen atom more electron-deficient. Therefore, the given statement is false.

7. The reaction between Toluidine+ CCl3CH(OH)2 + NH2OH.HCl produces.

P-iodobenzoic acid

Isonitrosoacetamide

2-hydroxyimino-N-phenyl acetanilide

2-hydroxyimino-N-Phenylacetamide

The reaction between Toluidine, CCl3CH(OH)2, and NH2OH.HCl produces 2-hydroxyimino-N-Phenylacetamide.

Explanation

The reaction between Toluidine, CCl3CH(OH)2, and NH2OH.HCl produces 2-hydroxyimino-N-Phenylacetamide.

8. O-nitrophenol and p-nitrophenol can be separated by fractional distillation using a Hempel column.

True

False

O-nitrophenol and p-nitrophenol cannot be separated by fractional distillation using Hempel column because they have very similar boiling points and would not form distinct fractions during the distillation process. Alternative separation techniques such as chromatography or solvent extraction would be more suitable for separating these compounds.

Explanation

O-nitrophenol and p-nitrophenol cannot be separated by fractional distillation using Hempel column because they have very similar boiling points and would not form distinct fractions during the distillation process. Alternative separation techniques such as chromatography or solvent extraction would be more suitable for separating these compounds.

9. The boiling point of solutions is the temperature at which the vapor pressure equals the external pressure.

True

False

The boiling point of solutions is not solely determined by the vapor pressure equaling the external pressure. The boiling point of a solution is actually higher than the boiling point of the pure solvent due to the presence of solute particles, which disrupt the intermolecular forces and require more energy to break the bonds and convert into vapor. Therefore, the statement is false.

Explanation

The boiling point of solutions is not solely determined by the vapor pressure equaling the external pressure. The boiling point of a solution is actually higher than the boiling point of the pure solvent due to the presence of solute particles, which disrupt the intermolecular forces and require more energy to break the bonds and convert into vapor. Therefore, the statement is false.

10. We use vacuum distillation to separate thermolabile liquid compounds at 1atm.

True

False

Vacuum distillation is used to separate heat-sensitive or thermolabile liquid compounds at reduced pressure (below atmospheric pressure), not at 1atm. By lowering the pressure, the boiling point of the compounds decreases, allowing for separation without decomposition. Therefore, the given statement is false.

Explanation

Vacuum distillation is used to separate heat-sensitive or thermolabile liquid compounds at reduced pressure (below atmospheric pressure), not at 1atm. By lowering the pressure, the boiling point of the compounds decreases, allowing for separation without decomposition. Therefore, the given statement is false.

11. The splash head is used in

Simple distillation

Fractional distillation

Steam distillation

Vacuum distillation

Steam distillation is a technique used to separate volatile compounds from non-volatile substances. In this process, steam is passed through the mixture, causing the volatile compounds to vaporize. The vapor is then condensed and collected, resulting in the separation of the desired compound. The splash head is a crucial component in steam distillation as it helps in controlling the flow of steam and preventing any splashing or loss of the mixture. Therefore, the splash head is specifically designed for steam distillation, making it the correct answer.

Explanation

Steam distillation is a technique used to separate volatile compounds from non-volatile substances. In this process, steam is passed through the mixture, causing the volatile compounds to vaporize. The vapor is then condensed and collected, resulting in the separation of the desired compound. The splash head is a crucial component in steam distillation as it helps in controlling the flow of steam and preventing any splashing or loss of the mixture. Therefore, the splash head is specifically designed for steam distillation, making it the correct answer.

12. A + B → AB M.Wt of A= 137.135 g/mol M.Wt of B= 140.732 g/mol M.Wt of AB= 248.017 Calculate the theoretical yield if the volume of A= 10 ml, B=25ml, AB= 40 ml And the density of A=1.5 g/ml, B= 2 g/ml, AB= 2.3 g/ml

50.87

88.11

27.03

1.73

The theoretical yield can be calculated by first determining the number of moles of A, B, and AB using their respective volumes and densities. Then, using the molar mass of AB, the number of moles of AB can be converted to grams. The theoretical yield is the mass of AB obtained from the reaction. In this case, the theoretical yield is 27.03 grams.

Explanation

The theoretical yield can be calculated by first determining the number of moles of A, B, and AB using their respective volumes and densities. Then, using the molar mass of AB, the number of moles of AB can be converted to grams. The theoretical yield is the mass of AB obtained from the reaction. In this case, the theoretical yield is 27.03 grams.

13. Chloral hydrate is more stable than chloral so we use it in the synthesis of iso nitroso acetanilide.

True

False

Chloral hydrate is not more stable than chloral, therefore it is not used in the synthesis of iso nitroso acetanilide.

Explanation

Chloral hydrate is not more stable than chloral, therefore it is not used in the synthesis of iso nitroso acetanilide.

14. Oxidation of phenols by a strong oxidizing agent produces carboxylic acids.

True

False

The statement is false because the oxidation of phenols by a strong oxidizing agent does not produce carboxylic acids. Instead, it produces quinones. Carboxylic acids are typically formed when alcohols are oxidized, not phenols.

Explanation

The statement is false because the oxidation of phenols by a strong oxidizing agent does not produce carboxylic acids. Instead, it produces quinones. Carboxylic acids are typically formed when alcohols are oxidized, not phenols.

15. Why is cooling in an ice bath required during the synthesis of p-iodobenzoic acid from p-aminobenzoic acid?

To avoid the decomposition of p-aminobenzoic acid.

To prevent the formation of unwanted by-products.

To control the diazotization reaction and prevent side reactions.

To enhance the solubility of p-aminobenzoic acid in the reaction mixture.

Cooling in an ice bath during the synthesis of p-iodobenzoic acid from p-aminobenzoic acid is crucial to control the highly exothermic diazotization reaction. Maintaining a low temperature (0-5°C) stabilizes the intermediate diazonium salt, preventing its decomposition and the formation of unwanted by-products. This ensures a successful Sandmeyer reaction, where the diazonium group is replaced with an iodine atom, yielding p-iodobenzoic acid with minimal side reactions.

Explanation

Cooling in an ice bath during the synthesis of p-iodobenzoic acid from p-aminobenzoic acid is crucial to control the highly exothermic diazotization reaction. Maintaining a low temperature (0-5°C) stabilizes the intermediate diazonium salt, preventing its decomposition and the formation of unwanted by-products. This ensures a successful Sandmeyer reaction, where the diazonium group is replaced with an iodine atom, yielding p-iodobenzoic acid with minimal side reactions.