Distillation and Extraction Quiz

Distillation is based on differences in:

• Molecular weight

• Density

• Boiling points

• Solubility

In a liquid-vapor diagram, the boiling point curve (liquid line) represents:

• The temperature at which the liquid starts to boil

• The temperature at which vapor starts to condense

• The pressure at which a substance evaporates

• The melting point of the substance

Substances separated by simple or fractional distillation must be:

• Miscible

• Immiscible

• Solid

• Gas

Simple distillation is used when the boiling point difference is:

• Less than 10°C

• At least 25°C

• At most 25°C

• More than 50°C

Fractional distillation is needed when the difference in boiling points is:

• At least 25°C

• Less than 25°C

• Exactly 25°C

• More than 100°C

What is the primary chemical basis for separating naphthalene, benzoic acid, and 3-nitroaniline?

• Differences in boiling points

• Differences in solubility and acid-base properties

• Differences in melting points

• Differences in polarity

A good extraction solvent should be:

• Immiscible with water and selectively dissolve the desired compound

• Completely miscible with water

• Highly reactive with the compound being extracted

• A strong acid

What is the role of MgSO₄ in extraction?

• To dry the organic solvent by removing water

• To dissolve the extracted compound

• To neutralize acidic impurities

• To increase solubility of the organic compound

How was caffeine characterized in the experiment?

• By measuring its boiling point

• Using Thin Layer Chromatography (TLC) and melting point analysis

• By measuring its density

• By dissolving it in water

How do you calculate the percentage of caffeine extracted?

• (Mass of extracted caffeine / Mass of starting material) × 100

• (Mass of solvent used / Mass of caffeine extracted) × 100

• (Volume of solvent used / Mass of caffeine extracted) × 100

• (Mass of caffeine extracted / Volume of solvent used) × 100