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Vital Force Theory, Its Limitations, And Definition of Organic Chemistry

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Introduction

The term 'organic' signifies life. Originally the term 'organic' was only applied to such substances which were obtained from plant and animal source (i:e from living organisms). It was Lavoisier, who first showed that carbon is the essential element in an organic compound. Nicolas Lemery in 1685, classified all known substances on the basis of their origin- as mineral, plant or animal but with the growth of knowledge, the distinction between plant and animal gradually disappeared and they were jointly termed as organic substances.

Vital Force Theory

As the organic compounds were believed to be obtained from living organisms (plants and animals), a Swedish chemist Berzelius in 1815 proposed that organic compounds could not be prepared in the laboratory and could be only produced by some mysterious force existing in the living organism, which forced was termed as 'Vital Force' (which comes from a latin word, 'vita' means 'life'), and this theory is known as vital force theory.

According to the vital force theory-

I) All organic compounds were isolated (extracted) from living bodies (plants and animals).

II) The organic compounds were the products of a vital force and could not be synthesized in the laboratory.

III) The organic compounds did not obey the laws of chemical combination to which organic compounds were subjected.

Limitations of Vital Force Theory

Friedrich Wohler during the crystallization of ammonium cyanate (NH4CNO), an inorganic compound, it was accidently superheated into a new fused mass. He analyzed the compound and confirmed the compound to be urea, an organic compound. After this event, he claimed that organic compounds are also possible to prepare in the laboratory.

$$(NH_4)_2SO_4 + 2KCNO \xrightarrow {\Delta} 2NH_4CNO + K_2SO_4$$

$$NH_4CNO \xrightarrow {rearrangement} NH_2CONH_2 (urea) $$

Initially, it was not accepted (fellow society assumed that Wohler was against the god). Later on, it was supported by Kolbe by the synthetic preparation of acetic acid from its initial constituents carbon, hydrogen, and oxygen. Similarly, it was also supported by Berthelotby synthesizing methane (CH4) from its initial component carbon and hydrogen.

By this way, so-called 'Vital force Theory' was kicked out and was no more accepted.

Modern definition of Organic Compound

Organic compounds are hydrocarbon and their derivatives.

Carbon tetrachloride is not a hydrocarbon but an organic compound because it is derived from hydrocarbon methane by the substitution reaction of it with four molecules of chlorine in the presence of sunlight.

$$CH_4 + 4Cl_2 \xrightarrow {sunlight} CCl_4 +4HCl$$

Reasons for Separate Study of Organic and Inorganic Compounds

The fundamentals of organic and inorganic chemistry remain same only for the convenience it has been separated from the inorganic. Few points of differences are considered which are listed below:

Organic compound Inorganic compound

Out of 105 elements of the periodic table only following elements are involved in the formation of the organic compounds and they are about 4 million in number.

O2, C, H2, N2, S, P, F2, Cl2, B2, I2

Out of 105 elements of the periodic table more than 90 elements are involved in the formation of the inorganic compounds. They are about 1 million in number.
Most of the organic compounds are liquids and gasses but solids are also found. Therefore, they are soluble in organic salts. Most of the inorganic compounds are solids and ionic in nature. Therefore, they are soluble in water.
They possess low melting point and boiling points than inorganic compounds. They possess high melting point and boiling points.
Most of the organic compounds are colored. Most of the inorganic compounds are colorless except transition metal compounds.
Most of the organic class of compounds are characterized by their own odor. Example- Alcohol (Alcoholic odor), aldehyde (fruity smell) e.t.c. Most of the inorganic compounds are odorless.
As organic compounds are covalently bonded compound, they show isomerism. They generally do not show isomerism.

Animals, plants, petroleum, coal tar, and some artificial synthetic methods are the sources of the organic compound .

Importance of Organic Chemistry

Organic chemistry plays a vital role in our daily life because the existence of living life is not possible without organic compounds. It is because organic compounds are present in-

a) Food: Food is mainly composed of organic compounds.

b) Clothes: Fibres which are used for clothing are composed of organic compounds.

c) Medicines: Medicines are composed of organic compounds.

Likewise, Analgesics, Insecticides, and pesticides, explosives as well as industries need organic compounds to function.

Reference

Adhikari, Rameshwar; Khanal, Santosh; Subba , Bimala; Adhikari, Santosh; Khatiwada, Shankar Pd. Universal Chemistry XI. First. Vol. 1st. Kathmandu: Oasis Publication, 2069.

Chaudhary, Ganga Ram; Karna, Shila Kant Lal; Sharma, Kanchan; Singh, Sanjay; Gupta, Dipak Kumar. A Textbook of Higher Secondary Chemistry XI. Ed. 2nd. Kathmandu: Vidyarthi Pustak Bhandar, 2069 (2012).



  •  A Swedish chemist Berzelius in 1815 proposed that organic compounds could not be prepared in the laboratory and could be only produced by some mysterious force existing in the living organism, which forced was termed as 'Vital Force' (which comes from a latin word, 'vita' means 'life'), and this theory is known as vital force theory.
  • Nicolas Lemery in 1685, classified all known substances on the basis of their origin- as mineral, plant or animal but with the growth of knowledge, the distinction between plant and animal gradually disappeared and they were jointly termed as organic substances.
  • Friedrich Wohler during the crystallization of ammonium cyanate ( NH4CNO), an inorganic compound, it was accidently superheated into a new fused mass. He analyzed the compound and confirmed the compound to be urea, an organic compound. After this event, he claimed that organic compounds are also possible to prepare in the laboratory.
  • Organic compounds are hydrocarbon and their derivatives.
  • Carbon tetrachloride is not a hydrocarbon but an organic compound because it is derived from hydrocarbon methane by the substitution reaction of it with four molecules of chlorine in the presence of sunlight.
  • Organic chemistry plays a vital role in our daily life because the existence of living life is not possible without organic compounds.
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