Estimation of C and H

For estimating the components in an organic compound, Liebig’s Method is applied. In the presence of dry cupric oxide, the organic molecule is heated. The oxidation of elements into CO2 and H2O occurs when they are heated. The caustic soda KOH and anhydrous CaCl2 absorb the oxidised compounds produced. The proportion of an element in a known mass may be calculated using the mass adsorbed.

Quantitative analysis:

Quantitative analysis is a type of analysis that may be used to figure out how many elements or molecules are created during a reaction. Carbon and hydrogen make up organic molecules. Oxygen, nitrogen, phosphorus, sulphur, and halogens are among the elements found in them.

Carbon and Hydrogen in a Compound:

Combustion analysis:

Combustion analysis is the most popular way of detecting how much carbon and hydrogen are contained in a molecule. Combustion analysis involves burning a substance in the presence of pure oxygen, which yields solely carbon dioxide and water as products.

The masses of carbon dioxide and water generated are measured, and the quantity of carbon and hydrogen contained in the original molecule may be simply approximated by comparing the original compound’s mass to the masses of carbon dioxide and water created. A bomb calorimeter is a piece of scientific equipment that is commonly used for this sort of experiment.

Liebig’s method for calculating carbon and hydrogen.

In Leibig’s method, a known mass of an organic substance is fully oxidised using cupric oxide. CO2 and H2O are formed when the C and H are oxidised. By passing CO2 and H2O  generated through a hyd.  CaCl2 tube and a KOH solution tube, the mass of CO2 and H2O created may be calculated. The percent of C and H is computed using these masses of CO2 and H2O. 

Procedure:

• In Liebig’s method, a known quantity of the organic substance is heated vigorously in the presence of pure oxygen, with the carbon present being oxidised to carbon dioxide and the hydrogen being oxidised to water. The chemical reaction of combustion is as follows.

• After passing through a U-shaped tube holding anhydrous calcium chloride, the combustion products are sent to the caustic potash container. Caustic potash interacts with carbon dioxide gas when anhydrous calcium chloride absorbs the water content.

• The carbon dioxide and water that are produced are weighed and collected.

• The mass of carbon dioxide and water generated is used to compute the proportion of carbon and hydrogen in the chemical. The equipment for Liebig’s test is depicted in the diagram below.

• The conversion of carbon and hydrogen in an organic substance to carbon dioxide and water is used to estimate their amounts. As a result, Liebig’s test is appropriate for estimating the amount of carbon and hydrogen in organic molecules.

• Note: If nitrogen is present in the organic component, it is oxidised to nitrogen oxides, which are also absorbed in caustic soda bottles under combustion circumstances. In such circumstances, reduced copper gauze is put near the tube’s exit end, converting nitrogen oxides to nitrogen gas.

Additional Information:

• Heating cupric oxide can be used to estimate elements other than carbon and hydrogen. The following is a modified version of the method:

• The caustic soda absorbs nitrogen oxides such as NO,N2O ,and others. A bright copper gauge is used to eliminate them. The following are the reactions:

• The non-volatile silver halide is formed when the halogen in the organic component is eliminated using a silver gauge.

• Sulphur is removed from the molecule by generating a lead sulphate with fused lead chromate.

Note: Test for carbon and hydrogen: A carbon and hydrogen-containing substance is heated in the presence of CuO in a dry test tube. The carbon is converted to CO2 while the hydrogen is converted to H2O. The H2O gas turns the anhydrous copper sulphate blue and the CO2 gas turns the lime water milky. The presence of carbon and hydrogen is confirmed by this inference.

Conclusion:

For the estimate of “Carbon and hydrogen,” Liebig’s method is used. In the presence of pure oxygen, a known mass of organic substance gets heated. The CO2 and water that are produced are collected and weighed.

The mass of carbon dioxide and water are used to compute the percentages of carbon and hydrogen in the chemical. The conversion of carbon and hydrogen in an organic substance to CO2 and H2O respectively, is used to estimate their amounts.

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