UNIT 1 CHARCOAL ANALYSIS – INORGANIC CHEMISTRY PRACTICALS

UNIT 1 CHARCOAL ANALYSIS

1.0  Introduction

2.0  Objective

1. Main Content
2. Procedure  
3. Requirements for Report

4.0  Conclusion

5.0  Summary

6.0  Tutor Marked Assignments

7.0  References/Further Reading

1.0 Introduction

Fossil fuels represent a large portion of the world’s energy supply. They also serve as an economical source of raw materials for the manufacture of products such as plastics, synthetic fabrics, and medicines. A very important property of a fuel is its heat of combustion which is the amount of heat (calories, joules, or BTU’s) released per amount of fuel (barrels, cubic feet, or tons). The energy rating of a fossil fuel gives us information about its chemical composition. Although charcoal is not a fossil fuel, but amorphous carbon from the incomplete combustion of animal or vegetable matter, its chemical composition can be analyzed in the same fashion as fossil fuels. The average person is more familiar with charcoal as the energy source for cooking on outdoor grills.

2.0 Objectives

At the end of this unit you should be able to perform experiments to determine
the ash, fixed carbon, moisture, and volatile combustible matter (VCM) for charcoal.

1. Main Content
2. Procedure

1. Moisture Content

Support a clean, empty crucible and lid on a clay triangle using a ring stand. Heat the crucible with a hot burner flame for several minutes to burn off any impurities. Handle the crucible and lid with crucible tongs for the remainder of the experiment. Move the crucible and lid to the carrying tray, allow to cool, and weigh to the nearest 0.001 g. Add approximately 1 g of charcoal to the crucible and weigh again. The lid may be weighed separately since its use is not required in the first section of the procedure. Put the crucible in a 100 ml beaker marked for easy identification and place in a drying oven for 1 hour. Allow crucible to cool and reweigh. The weight loss represents the moisture content of the charcoal.

1. Volatile Combustible Matter, VCM

Now support the crucible and dried charcoal in a clay triangle and cover with the lid leaving a slight opening at one side.

Initially, heat the apparatus gently, gradually increasing to a hot flame for several minutes. Use tongs to close the lid completely and allow the sample to cool to room temperature. Before weighing the crucible, examine the upper portion of the crucible and the lid for deposits and discolorations. If deposits appear on the lid, heat it directly in the flame. If deposits appear on the crucible, carefully heat the upper portion of the crucible without the lid and avoid heating the charcoal sample. Weigh the crucible, lid and remaining sample, when cool, to the nearest 0.001g. The weight loss is the VCM evolved during the heating process.

1. Ash and Fixed Carbon

Support the crucible in the clay triangle and partially cover it with the lid. Heat the sample intensely and if the sample ignites, use the tongs to cover the crucible until flame is extinguished. Continue intense heating until no black residue remains on the lid or in the crucible. This will require that you periodically use the tongs to rotate the crucible’s position in the flame. The residue in the crucible should appear to be a light gray-brown color when the combustion has been completed. Cool the crucible, lid, and contents and weigh. The residue remaining in the crucible is the ash content. The weight loss after the VCM removal is the fixed carbon content. Repeat the entire procedure for a
second trial.

3.2 Requirements for Report

Tabulate the data collected in the experiment and calculate the percentages of ash, fixed carbon, moisture and VCM from data. Pay attention to significant digits in the data and reported numbers. Comment on the consistency or inconsistency of values from the two trials.

4.0  Conclusion

Charcoal is a light black residue consisting of carbon, and any remaining ash, obtained by removing water and other volatile constituents from animal
and vegetation
substances. The moisture, volatile matter, and ash results are typically among the primary parameters used for assessing the quality of a solid fuel material. The moisture result is utilized for calculating the dry basis results of other analytical results. The ash result is utilized in the ultimate analysis calculation of oxygen by difference and for calculating material balance and ash load purposes in industrial boiler systems. The volatile matter result indicates the coke yield on the carbonization process providing additional information on combustion characteristics of the materials, and establishes a basis for purchasing and selling the solid fuel materials. Fixed carbon is a calculated value of the difference between 100 and the sum of the moisture, ash, and volatile matter where all values are on the same moisture reference base.

5.0  Summary

In this unit, you have carried out the analysis of charcoal. You have determined the moisture content, Volatile Combustible Matter, the ash content as well as the fixed carbon

6.0  Tutor Marked Assignments(TMAs)

1. Of the four determinations in the experiment, which is proportional to the heat content or would be equivalent to an energy rating?
2. Identify in each section of the procedure whether a physical or chemical change is being used to analyze the charcoal.