Physical Chemistry

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What is Physical Chemistry?

I am sure you have found those images of molecular structures in your chemistry book fascinating or even overwhelming, didn’t you? Well, it is an interesting subject, no doubt. But if you are struggling with certain concepts in Physical Chemistry, don’t worry! We are here at your rescue! Physical chemistry is basically a branch of chemistry that deals with how chemical compounds react with other matter, their chemical compounds, and what binding forces hold their atoms together. In simple words, this branch of chemistry attempts to study the way matter behaves on both an atomic and molecular level (that is, the macroscopic aspects) and how different chemical reactions occur.

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The Branches of Physical Chemistry

Now we know that this branch of chemistry deals with the chemical systems of matter in terms of concepts, practices, and principles of physics, including energy, motion, force, thermodynamics, time, equilibrium, etc. Hence, this branch of chemistry tries to solve the following areas -

  1. Intermolecular forces acting upon physical properties of various matter (like surface tension in liquids, tensile strength, and plasticity).

  2. The identity of electrical conductivity and ions of materials.

  3. Electrochemistry and surface science of cell membranes

  4. Transfer of heat between various chemical systems and their surroundings during a chemical reaction (the process is known as thermochemistry).

  5. Reactions of electrochemical cells (a device that either derives or uses electricity from or to cause chemical reactions).

  6. Interaction between two bodies in terms of quantities of work and heat exchanged (a branch known as thermodynamics).

  7. The branch of chemical kinetics or reaction kinetics deals with the rate of chemical reactions and their feasibility, together with other aspects affecting the rate of reactions, such as the concentration of reactants or the presence of a catalyst.

  8. Spectroscopy is another branch that focuses on the interaction between different matter and electromagnetic radiations.

  9. Quantum chemistry is concerned about the strength and shapes of chemical bonds and the manner of movements of atomic nuclei.

You can get a better understanding of each of these concepts in reference textbooks like Peter Atkins’ Physical Chemistry or “The Essentials of Physical Chemistry” by Arun Bahl. You can also give a reading of the “Current Physical Chemistry”, which is an essential journal that keeps physical chemists updated with the latest development and issues in physical chemistry.


Scales in Physical Chemistry

While studying advanced physical chemistry, we need to understand the following major scales associated with this branch of chemistry -

  1. The Macroscopic Scale: This scale deals with the substances that can be studied with the naked eye without taking the help of any optical equipment. Some of the major qualities estimated using the macroscopic scale are -

    1. Boiling and Melting points

    2. Latent heat of vaporization

    3. Linear thermal expansion and its coefficient

    4. Enthalpy of fusion

For example, a water molecule may exist in three states, including solid, liquid, and gaseous if studied under the macroscopic scale. However, we cannot identify its molecular components of water (i.e., H2O) using this scale.

  1. The Microscopic Scale: In this scale, we attempt to study the properties of substances, which are not visible to the human eye. To do so, we use several optical instruments like microscopes to have a magnified view of the chemical compounds of matter. An example would be to study the structures and shapes of crystals.

  2. The Atomic Scale: Using the atomic scale, we study the atomic properties of matter, which vary depending on the element. Based on this, we group together elements having similar properties in the periodic table. For instance, we can study atomic number, atomic mass, and the bond strength between atoms in a molecule using the atomic scale.

  3. The Subatomic Scale: This scale studies the particles that are smaller in size than atoms and hence, are named subatomic particles. Using this scale, we can study the dual nature of particles, which is why they are known as energy or waves. A popular application of this can be found in nuclear chemistry.


Did You Know?

Did you know simple everyday activities like cooking, burning, rotting, rusting, or even as basic as ice melting or sugar cubes dissolving in water are all good examples of physical chemistry? Sounds so familiar, right?

You may have seen some basic chemical reactions in your school lab, such as putting alkali metal in water, placing copper in nitric acid, or simply mixing some different acidic solutions in your test tube.

Further, if you love physics, which I am sure most of you do, you will definitely like physical chemistry. Here, you can work with your favorite concepts like force, time, motion, energy, thermodynamics, and many more.

FAQs (Frequently Asked Questions)

Q1. What is Physical Organic Chemistry? What is the Difference Between Physical Chemistry, Inorganic Chemistry, and Organic Chemistry?

Ans: Physical organic chemistry is a branch of organic chemistry that studies the relationship between different chemical structures and their reactivity by studying the nature and behavior of organic molecules using experimental tools. Coming to the difference between physical chemistry, organic chemistry, and inorganic chemistry, the former is the study of chemical compounds at the molecular and atomic levels by applying theories and principles of physics. Organic chemistry is the study of molecular structures, properties, reactions, and compositions of carbon compounds, including hydrocarbons and elements like hydrogen, oxygen, nitrogen, halogens, silicon, phosphorus, and sulfur. Inorganic chemistry, on the other hand, focuses on the properties and behavior of inorganic compounds and various elements, including minerals, metals, and organometallic compounds. In simple terms, inorganic chemistry studies both carbon-containing elements and other compounds.

Q2. What are the Applications of Physical Chemistry?

Ans: There may be endless applications of this branch of chemistry, but the common goal of physical chemists is to discover, evaluate, and understand the fundamental physical characteristics of matter in any form, be it solid, liquid, or gas. They work at the atomic level of materials, and hence, many of the applications can be found in industries involving the development or manufacture of different materials, like ceramics, plastics, fuel formulation, electronics, batteries, catalysis, colloids, surfactants, personal care products, and even the construction of aircraft and bridges. Therefore, most physical chemists are found working as analytical chemists or material scientists in these industrial sectors. Some significant applications are also found in the food science and pharmaceutical sector to develop new food items, drugs, medicines, and other medicinal products.

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