Purification of Benzoic Acid by Crystallization - MeitY OLabs

amritacreate

2 Feb 201503:41

EducationalLearning

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TLDRThe video demonstrates the purification of benzoic acid through crystallization. It explains the steps to prepare pure benzoic acid crystals from an impure sample, including solution preparation, hot solution filtration, cooling of the saturated solution, and crystal separation and drying. The required materials and detailed procedure are outlined, ensuring clarity for replicating the process. Key precautions, such as undisturbed cooling and thorough filtration, are emphasized to achieve the best results.

Takeaways

🔬 Benzoic acid is a colorless crystalline solid and an aromatic carboxylic acid.
🧪 Pure crystals of benzoic acid can be prepared from an impure sample by crystallization.
📝 The crystallization process involves preparation of a solution, filtration of the hot solution, cooling, and separation and drying of crystals.
🛠️ Materials required include crude benzoic acid, distilled water, cold water, beakers, funnel, filter paper, glass rod, spatula, fluted filter paper, test tube, stand with clamp, trough, wire gauze, tripod stand, and Bunsen burner.
💧 Preparation of the solution involves boiling distilled water, dissolving benzoic acid in boiling water, and stirring with a glass rod.
🔍 Filtration of the hot solution involves using fluted filter paper in a funnel, clamping the funnel to a stand, and collecting the filtrate in a beaker.
❄️ Cooling the hot saturated solution is done by letting it come to room temperature and then cooling it in a trough with cold water, leading to the separation of white crystals.
🧼 Separation and drying of crystals involves filtering the crystals, washing them with cold water, and drying them between filter papers.
📦 The dried crystals are then transferred to a dry test tube, appearing as opaque white crystals.
⚠️ Precautions include cooling the solution without disturbing it and ensuring the removal of insoluble impurities by filtration.

Q & A

What is the main objective of the described procedure?
-The main objective is to prepare pure crystals of benzoic acid from an impure sample through the process of crystallization.
What type of substance is benzoic acid described as?
-Benzoic acid is described as a colorless crystalline solid and an aromatic carboxylic acid.
What materials are required for the crystallization process?
-Materials required include a crude sample of benzoic acid, distilled water, cold water, beakers, funnel, filter paper, glass rod, spatula, fluted filter paper, test tube, stand with clamp, trough, wire gauze, tripod stand, and a Bunsen burner.
Why is it important to gradually add boiling water to the crude benzoic acid sample?
-Gradually adding boiling water ensures that only the minimum quantity necessary to dissolve the benzoic acid is used, which helps in achieving a saturated solution that can form crystals upon cooling.
What is the purpose of using a fluted filter paper during filtration?
-The fluted filter paper increases the surface area for filtration, which helps in efficiently separating the insoluble impurities from the solution.
Why should the hot saturated solution be allowed to cool slowly?
-Cooling the hot saturated solution slowly allows the crystals of benzoic acid to form gradually, leading to better crystal formation and purity.
What precautions should be taken when cooling the hot saturated solution?
-The solution should be cooled without disturbing it to ensure proper crystal formation, and insoluble impurities should be removed by filtration.
How are the crystals of benzoic acid dried after filtration?
-The crystals are placed on a filter paper to soak up any solution, then transferred to another filter paper and dried by pressing gently between the folds of the paper.
What visual characteristics should the purified benzoic acid crystals have?
-The purified benzoic acid crystals should appear as opaque white crystals.
What is the role of cold water in the crystallization process?
-Cold water is used to cool the hot saturated solution, which facilitates the crystallization of benzoic acid by lowering the solubility of the substance in the solution.

Outlines

00:00

🔬 Purification of Benzoic Acid by Crystallization

Benzoic acid is a colorless crystalline solid and an aromatic carboxylic acid. Pure crystals of benzoic acid can be prepared from an impure sample through crystallization. This process involves preparing a solution of the impure sample, filtering the hot solution, cooling the hot saturated solution, and separating and drying the crystals. The goal is to obtain pure benzoic acid crystals from an impure sample.

🧪 Materials Required

The materials needed for the crystallization process include a crude sample of benzoic acid, distilled water, cold water, 250 ml beakers, funnel, filter paper, glass rod, spatula, fluted filter paper, test tube, stand with clamp, trough, wire gauze, tripod stand, and a Bunsen burner.

🚰 Preparation of Solution of the Impure Sample

To prepare the solution of the impure sample, take about 150 ml of distilled water in a beaker and boil it over a Bunsen burner. In another beaker, take about 3 g of crude benzoic acid and gradually add a minimum quantity of boiling water using a dropper, just enough to dissolve the benzoic acid while stirring with a glass rod. Heating may be necessary to completely dissolve the benzoic acid.

🧹 Filtration of the Hot Solution

Place a fluted filter paper in a funnel and clamp the funnel to a stand with a beaker underneath. Pour the solution through the funnel over a glass rod to collect the filtrate in the beaker, leaving insoluble impurities on the filter paper.

❄️ Cooling the Hot Saturated Solution

Allow the filtrate to come to room temperature, then cool it by placing the beaker in a trough containing cold water. As the solution cools, white crystals of benzoic acid will begin to separate.

🧴 Separation and Drying of Crystals

Clamp the funnel with a filter paper to the stand, place a beaker underneath, and separate the crystals by filtration. Wash the crystals with cold water, then transfer them to a filter paper to soak up the solution. Dry the crystals by pressing them gently between the folds of another filter paper. Finally, transfer the dry crystals to a test tube. The purified benzoic acid crystals will appear opaque white.

⚠️ Precautions

Ensure to cool the hot saturated solution without disturbing it and remove insoluble impurities by filtration to achieve successful crystallization.

Mindmap

Keywords

💡Benzoic Acid

Benzoic acid is a colourless crystalline solid and an aromatic carboxylic acid. In the context of the video, benzoic acid is the primary substance being purified through crystallization. This compound's purity is essential for the process being demonstrated.

💡Crystallization

Crystallization is a method used to purify substances by forming solid crystals from a solution. In the video, crystallization is the process through which pure benzoic acid crystals are obtained from an impure sample, illustrating the step-by-step procedure involved.

💡Preparation of Solution

This step involves dissolving the impure benzoic acid sample in boiling distilled water. It is crucial as it prepares the mixture from which benzoic acid will be crystallized. The video details the addition of boiling water to the benzoic acid until it dissolves completely.

💡Filtration

Filtration is used to separate insoluble impurities from the solution. In the video, a fluted filter paper and funnel are used to filter the hot solution, leaving impurities on the filter paper and collecting the filtrate in a beaker.

💡Cooling

Cooling the hot saturated solution allows benzoic acid to crystallize. The video explains the process of letting the filtrate reach room temperature and then cooling it further in cold water, which helps in the formation of white benzoic acid crystals.

💡Separation of Crystals

This step involves separating the formed benzoic acid crystals from the solution. The video shows how crystals are collected by filtration and then washed with cold water to remove any remaining impurities.

💡Drying of Crystals

Drying the benzoic acid crystals ensures they are free from any solution. The video demonstrates how the crystals are placed on filter paper to soak up the solution and then dried further by pressing them gently between folds of filter paper.

💡Impure Sample

An impure sample contains benzoic acid mixed with various impurities. The video starts with a crude sample of benzoic acid, emphasizing the need to purify it to obtain pure crystals through the crystallization process.

💡Distilled Water

Distilled water is pure water used to dissolve the impure benzoic acid sample. The video specifies using distilled water to ensure no additional impurities are introduced during the preparation of the solution.

💡Fluted Filter Paper

Fluted filter paper is a type of filter paper folded to increase surface area for filtration. In the video, it is used during the filtration step to efficiently separate insoluble impurities from the benzoic acid solution.

Highlights

Purification of Benzoic Acid by Crystallization

Benzoic acid is an aromatic carboxylic acid

Crystallization process explained

Preparation of solution of the impure sample

Dissolution of benzoic acid

Use of filtration to remove impurities

Cooling of the hot saturated solution

Formation of benzoic acid crystals

Separation of crystals by filtration

Washing of crystals with cold water

Drying of crystals on filter paper

Transfer of dried crystals to a test tube

Precaution in cooling the solution

Removal of insoluble impurities

Use of distilled water

Use of glass rod for stirring

Use of Bunsen burner for heating

Use of cold water for cooling

Equipment list provided

Transcripts

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