Praktikum Kimia Kayu Materi 3 Alkohol Benzen

Summary

This script outlines the process of extracting soluble substances from wood using an alcohol-benzene method. The procedure includes grinding the wood into fine particles, extracting with a 1:2 alcohol-benzene mixture, and using a Soxhlet extraction apparatus for 4-6 hours. After extraction, the solvent is removed by vacuum, and the sample is washed with alcohol. The weight loss of the sample, after drying, helps determine the percentage of extractable substances in the wood. An alternative method involves using an extraction flask to evaporate the solvent. This analysis targets components like wax, fat, and resin present in the wood.

Takeaways

• 😀 The script discusses the procedure for wood extraction using alcohol-benzene solvent method, focusing on the preparation and chemical analysis of wood.
• 😀 Wood samples must be finely ground to ensure thorough reactions during chemical analysis.
• 😀 According to ASTM standards, wood particle size for chemical analysis should pass through a 40 mesh sieve or 0.04050 mm.
• 😀 The extraction process eliminates non-wood substances that could interfere with chemical analysis.
• 😀 Alcohol-benzene solvent (96% alcohol and benzene in a 1:2 volume ratio) is used to extract waxes, fats, resins, and other substances from wood.
• 😀 The extraction equipment includes Soxhlet apparatus, a 30-40 mm diameter extraction thimble, 100 mm capacity condenser, and vacuum filtration setup.
• 😀 A 2.0g sample of ground wood is placed in a pre-weighed container, and extraction is conducted with alcohol-benzene solution for 4-6 hours.
• 😀 The solvent level should be maintained, and the extraction process includes four rinses per hour.
• 😀 After extraction, the solvent is removed by vacuum, and the sample is washed with alcohol to eliminate benzene.
• 😀 The extracted wood is dried in an oven at 105°C ± 3°C until a constant weight is achieved, and the reduction in weight is used to calculate the extractive content.

Q & A

What is the purpose of the alcohol-benzene extraction method for wood analysis?

The alcohol-benzene extraction method is used to remove substances such as waxes, fats, and resins from wood, which can interfere with chemical analysis. This prepares the wood sample for further detailed analysis.

What is the required particle size for wood when preparing it for chemical analysis?

According to ASTM standards, the wood particles should pass through a sieve of 40 mesh or 0.0405 mm to ensure proper reaction with the reagents used in the analysis.

Why must non-wood substances be removed before conducting the chemical analysis?

Non-wood substances such as waxes, fats, and resins can interfere with the chemical reactions needed for accurate analysis of the wood’s composition.

What are the required equipment and chemicals for the alcohol-benzene extraction process?

The required equipment includes a Soxhlet extractor, a 100 mm diameter condenser, and an analytical balance. The chemicals used are 96% alcohol and a benzene-alcohol mixture in a 1:2 volume ratio.

How is the wood sample prepared for extraction?

The wood sample, finely ground into powder, is weighed and placed in a pre-weighed crucible, which is then positioned in the Soxhlet extractor for the extraction process.

What is the procedure for the extraction process using the Soxhlet extractor?

The extraction is carried out by heating a mixture of alcohol and benzene (1:2 ratio) for 4-6 hours. The solution is maintained at a specific level and replenished every hour during the extraction.

How is the alcohol-benzene mixture handled after extraction?

After extraction, the wood sample is removed, and the solvent is evaporated using vacuum filtration to dry the sample. The sample is then washed with alcohol to remove residual benzene.

What is the drying procedure after extraction?

After washing with alcohol, the sample is dried in an oven at 105°C ± 3°C until a constant weight is achieved.

How is the extractive content calculated in the analysis?

The extractive content is determined by calculating the weight loss of the wood sample after extraction, with the final content expressed as a percentage of the dry weight.

What are the alternative methods for determining the extractive content in wood?

One method involves calculating the weight loss directly as described above, while the other method involves evaporating the solvent in an extraction flask, followed by drying the flask to determine the extractive weight.