Chemistry | Definition & History in Science

What is Chemistry in Science?

Chemistry, the main branch of pure science that deals with the physical or chemical properties, reactions, composition and, structure of atom or matter form by the element, interacts with the energy of the materials or substances for study or analysis of organic and inorganic compound or molecule. Different types of learning and analysis in chemistry help to generate different kinds of perfect research topics which use in many fields of science like agriculture, medicinal, environmental, etc. Inorganic, organic, physical, environmental, analytical are the basic branches of chemistry for the different classes of study and science analysis.

Organic and Inorganic Substances in Chemistry

Chemistry (physical, inorganic, organic, analytical) in pure science deals with chemical properties reactions composition of atom or molecule of matter

The common definition of organic chemistry is the chemistry of element carbon (compounds or molecules) but many carbon molecules like carbon monoxide, carbon dioxide, carbonates, and carbon disulfide are the kingdom of inorganic series. Therefore, the difference between organic and inorganic substances is very complicated. To differentiate different types of organic and inorganic molecules, the substances are classified into two groups in learning chemistry, substances prepared from green plants or animals (living world), substances not prepared from the living world.

Simple examples of pure organic compounds like sugar, starch, alcohol, resins, indigo, methane, ethylene in chemistry known from the earliest history but the chemical formula or reactions of the said molecules are still unknown. With the progress, about the beginning of the eighteen century Lemery (1675) published a famous science journal, Cours de Chemie. This chemistry journal divided the chemical substances from natural sources into three classes as substances come from mineral, from green plants, from the animal.

History of Organic Chemistry

Lemery’s definition in chemistry is accepted but very quickly Lavoisier (1784) provides new information for the classification of organic compounds or molecules on the basis of its sources. All compounds obtained from green plants and the animal sources always contain carbon and hydrogen atom, and frequently, nitrogen, oxygen, and phosphorus. Lavoisier also showing the close relationship between green plants and animal products. With the improvement of the analytical chemistry technique, the organic substances are reclassification into two classes, substances made from living organism and substances comes from non-living worlds.

Chemical science goes step by step by the scope of new information, changing definition or classifications, and production of the new substance or molecule in chemistry. In 1828 Wohler converted ammonium cyanate into urea, a substance obtained from animal sources. It changes the definition and classification of organic chemicals. The previous definition of organic molecule completely ended with the synthesis of acetic acid from its component chemical elements by Kolbe in 1845. Therefore, in the organic chemistry, we study of hydrocarbon or derivative of hydrocarbon compound or molecule.

Chemical Formula Analysis

The empirical formula in chemistry, define the relative number of each class of atom in the general molecular formula that helps for the calculation of percentage composition or chemical structure of the molecule or compound.

Question: If 0.202 gm of an organic compound gave on combustion 0.361 gm of carbon dioxide and 0.147 gm of water. What is the empirical formula of the compound in chemistry?

Answer: Weight of carbon in the said compound = (12/44) × 0.361 gm = 0.0985 gm, weight of the hydrogen = (2/18) × 0.147 = 0.0163 gm, and weight of oxygen = 0.202 – (0.0985 + 0.0163) = 0.0872 gm. Therefore, the ratio of molar mass of carbon, hydrogen, and oxygen atom or C : H : O = (0.0985/12) : (0.0163/1) : (0.0872/16) = 3 : 5.98 : 2. From the above solution, the empirical formula of said organic compound in chemistry, C3H6O2.

Molar Mass Analysis in Chemistry

The molecular formula in chemistry gives the actual number of atoms of each class of inorganic or organic elements obtained by multiplying some whole number in the empirical formula. The whole number in chemistry obtained from the molar mass or mole number and in many cases, the whole number is one. Many standard analytical methods like vapour density, the elevation of boiling point, depression of freezing point used in science for the chemical analysis of organic and inorganic substances.

The above standard example in chemistry help mainly for the general chart of molecules. But other physical methods like Graham’s law of diffusion, sedimentation, the viscosity of liquid and gases, osmotic pressure, X-ray radiation analysis, mass or atomic spectrum used for substances that contain high molar mass.

Introduction to Physical Science

Physical chemistry is the part of science where we study general definition, law, principle, properties, mathematical equation, or formula related to the atom, molecule, or matter. Therefore, the physical part of science or chemistry deals with the topics, properties of solid (amorphous and crystalline solid), gas (ideal and real gas, critical temperature), liquid, thermodynamics law of energy conservation, heat (molar or specific heat), chemical equilibrium, chemical kinetics, chemical catalyst, etc. But the study of physical chemistry is incomplete if the student confines himself only the theoretical information, he must gain the practical explanations of the theory, definition, problem, and solution.

What is Analytical Chemistry in Science?

Analytical chemistry meaning the analysis of the chemical formula, structure, composition of the atom, molecule, or matter in chemical, forensic, medicinal, and food science and technology. However, modern analytical chemistry definition help to identify general substances that function on composition, structure, and reaction analysis for different types of chemical importance. Therefore, the most difficult task for an analytical chemist is to explain what is the nature of analytical chemistry? It is an interdisciplinary domain of science where a large number of research topics contributed to its development.

All chromatographic studies in chemistry were invented by biochemists or biological scientists, while methods of the electromagnetic spectrum and mass spectroscopy were discovered by physicists. But if we close look, the different types of research topics published in a different set of science journals by using analytical methods, about 60% of such chemistry materials are published by persons who are not analytical chemists in the true sense.




Van't Hoff equation-equilibrium

Van’t Hoff Equation

Van't Hoff Equation-Temperature Effect on Equilibrium Van't Hoff equation connecting equilibrium constant and temperature by thermodynamics relation of Gibbs-Helmholtz free energy equation. The standard chemical...