Question

Simple distillation could be used to separate which of the following compounds? A. Toluene (boiling point of \(111^{\circ} \mathrm{C}\) ) and water (boiling point of \(\left.100^{\circ} \mathrm{C}\right)\) B. Naphthalene (boiling point of \(218^{\circ} \mathrm{C}\) ) and butyric acid (boiling point of \(\left.163^{\circ} \mathrm{C}\right)\) C. Propionaldehyde (boiling point of \(50^{\circ} \mathrm{C}\) ) and acetic acid (boiling point of \(\left.119^{\circ} \mathrm{C}\right)\) D. Benzene (boiling point of \(80^{\circ} \mathrm{C}\) ) and isopropyl alcohol (boiling point of \(\left.83^{\circ} \mathrm{C}\right)\)

Short answer

Option B and Option C.

Step-by-step solution

Understand Simple Distillation

Simple distillation is effective for separating compounds with a large difference in boiling points. Generally, the boiling points difference should be at least 25-30°C for simple distillation to be effective.

Evaluate Option A

Toluene has a boiling point of 111°C and water has a boiling point of 100°C. The difference in boiling points is 11°C.

Evaluate Option B

Naphthalene has a boiling point of 218°C and butyric acid has a boiling point of 163°C. The difference in boiling points is 55°C.

Evaluate Option C

Propionaldehyde has a boiling point of 50°C and acetic acid has a boiling point of 119°C. The difference in boiling points is 69°C.

Evaluate Option D

Benzene has a boiling point of 80°C and isopropyl alcohol has a boiling point of 83°C. The difference in boiling points is 3°C.

Compare Boiling Point Differences

Option B has a boiling point difference of 55°C, Option C has a boiling point difference of 69°C. Both of these options have sufficient boiling point differences for simple distillation.

Select the Correct Answer

Both Option B (naphthalene and butyric acid) and Option C (propionaldehyde and acetic acid) can be separated by simple distillation due to their sufficient boiling point differences.

Key concepts

boiling point differences

To understand simple distillation, it's crucial to grasp the concept of boiling point differences. Boiling points are the temperatures at which substances transition from a liquid to a gas. In simple distillation, separation of compounds occurs based on these differences. For simple distillation to work effectively, the compounds need a significant difference in their boiling points. Typically, a difference of at least 25-30°C is needed. This makes it easier for one compound to vaporize and subsequently condense separately from the other compound.
For example, if we look at the options in the original exercise:

• Option A: Toluene and water have a boiling point difference of 11°C, which is too small.
• Option B: Naphthalene and butyric acid have a difference of 55°C, which is sufficient.
• Option C: Propionaldehyde and acetic acid have a difference of 69°C, which is also sufficient.
• Option D: Benzene and isopropyl alcohol have a difference of only 3°C, which is insufficient.

Understanding these differences helps determine the feasibility of separation via simple distillation.

organic compounds

Organic compounds are molecules primarily made of carbon and hydrogen atoms, and they often contain elements like oxygen, nitrogen, sulfur, and halogens. In distillation, it's crucial to recognize the properties of these organic compounds such as their boiling points, polarity, and molecular weight. These properties significantly influence their behavior during the distillation process.
For instance:

• Toluene, which has a boiling point of 111°C, is an aromatic hydrocarbon.
• Naphthalene, with a boiling point of 218°C, is another aromatic compound but much heavier.
• Butyric acid, at 163°C, is an organic acid with a pungent smell.
• Propionaldehyde, having a boiling point of 50°C, is an aldehyde, and acetic acid, boiling at 119°C, is another organic acid.

Recognizing these properties helps in selecting suitable separation techniques. Organic compounds of different classes (aromatics, acids, aldehydes) exhibit different boiling points, thereby making distillation an effective method to separate them if they meet the boiling point criteria.

separation techniques

Separation techniques in chemistry are critical for isolating and purifying compounds. Simple distillation is one such method but only works effectively when the compounds have significant boiling point differences. It's a straightforward technique where the mixture is heated, and the compound with the lower boiling point vaporizes first. It then condenses back into a liquid in a separate container.
Here are the key steps in simple distillation:

• Heat the mixture: The compound with the lowest boiling point vaporizes first.
• Condensation: The vapor travels through a condenser and cools down to become liquid again.
• Collection: The condensed liquid is collected separately from the original mixture.

Another common separation technique is fractional distillation, which is used when boiling point differences are less than 25-30°C. This method uses a fractionating column to achieve better separation by repeated vaporization-condensation cycles. By understanding both methods, one can efficiently choose the right technique based on the properties of the compounds to be separated.