CP10 Preparation of a Pure Organic Solid

• What is the experimental objective of this practical?

  Prepare a pure organic solid
• The process used to prepare a pure organic solid is called recrystallization
• Steps involved in recrystallization

  1️⃣ Dissolve the impure solid in a suitable solvent

  2️⃣ Filter the solution to remove insoluble impurities

  3️⃣ Allow the pure solid to crystallize out as the solution cools
• Obtaining a pure organic solid is important for further analysis and use in chemical reactions
• Ethanol and water are examples of solvents that can be used in recrystallization.


  True
• The purity of the obtained solid is confirmed by measuring its melting point using a melting point apparatus
• What type of paper is used in filtration during recrystallization?

  Filter paper
• The experimental objective of recrystallization is to prepare a pure organic solid
• Match the reagent or equipment with its purpose:

  Impure solid ↔️ Starting material

  Solvent ↔️ Dissolves the solid

  Melting point apparatus ↔️ Measures melting point

  Hot plate ↔️ Provides heat for dissolution
• What is the purpose of a melting point apparatus in recrystallization?

  Confirms identity and purity
• During recrystallization, the solution is cooled to allow the pure solid to crystallize
• What is the purpose of washing the filtered solid with cold solvent?

  Removes residual impurities
• The drying step in recrystallization can be performed using a drying oven or air-drying


  True
• Steps for filtration and washing in recrystallization

  1️⃣ Filtration to separate solid crystals from hot solvent

  2️⃣ Washing the filtered solid with cold solvent

  3️⃣ Drying the washed solid by air or oven
• A drying oven provides a consistent drying environment
• Recrystallization begins with dissolving the impure solid in a minimal amount of hot solvent
• The purity of the obtained solid is confirmed by measuring its boiling point.

  False
• What property is measured to confirm the purity of the solid?

  Melting point
• Match the reagent with its purpose:

  Impure solid ↔️ Starting material

  Solvent ↔️ Dissolves the solid

  Hot plate ↔️ Provides heat for dissolving
• What equipment is used to measure the melting point of the solid?

  Melting point apparatus
• Wearing gloves and goggles is a safety measure during the experiment.


  True
• What does good ventilation ensure in the lab during the experiment?

  Reduces inhalation of fumes
• Use a hot plate or water bath for heating
• Wearing gloves and goggles is essential for safety in the lab

  True
• The first step in preparing a pure organic solid is to measure the required amounts of the impure solid and solvent
• Steps involved in recrystallization

  1️⃣ Dissolution in hot solvent

  2️⃣ Filtration to remove impurities

  3️⃣ Crystallization by cooling

  4️⃣ Drying to remove solvent
• Insoluble impurities are removed during the filtration step


  True
• After filtration, the solution is allowed to cool, causing the pure solid to crystallize
• The recrystallized solid is washed with cold solvent to remove traces of the original solvent


  True
• Comparing the melting point of the recrystallized solid to its expected value confirms its purity


  True
• A common solvent used in recrystallization is ethanol
• Preparing the required amounts of impure solid and solvent is the first step in setting up the experiment


  True
• The recrystallization process ensures a high degree of purity by selectively forming crystals of the desired compound

  True
• Steps for filtration and washing in recrystallization

  1️⃣ Filtration using funnel and paper

  2️⃣ Washing with cold solvent

  3️⃣ Drying the solid
• Washing the filtered solid with a small amount of cold solvent removes residual impurities
• Air-drying requires no electricity
• Percentage yield is calculated by comparing actual yield to theoretical yield.


  True
• Filtration in recrystallization removes soluble impurities.

  False
• Steps in recrystallization techniques

  1️⃣ Dissolution of the impure solid in hot solvent

  2️⃣ Filtration to remove insoluble impurities

  3️⃣ Crystallization by cooling the solution

  4️⃣ Drying the crystals
• Match the method with its characteristic:

  Air-drying ↔️ Slow drying process sensitive to humidity

  Drying oven ↔️ Fast drying time in a controlled environment