Zeroth law of thermodynamics Zeroth law of thermodynamics was established by Ralph H. Fowler in 1930. This law was formulated long after the first, second, and third laws of thermodynamics had been widely recognized. But since this law was considered to be of primary importance. So it was named as zeroth law of thermodynamics. This law … Read more
Concept of heat and work Work The product of force and displacement is known as work. i.e., Work = Force × Displacement W = F × â„“ Consider a gas enclosed in a cylinder fitted with a frictionless piston. Suppose, a = area of cross section of the cylinder. p = pressure of the piston … Read more
Thermodynamic Processes Thermodynamics deals with changes that occur in the properties of a system when the system goes from one equilibrium state to another. Such a change in the values of properties of a system is called a process. Alternatively, when a thermodynamic system changes from one state to another, the operation is called a … Read more
State and path functions and their differentials State of the system State of a thermodynamic system is described by its measurable or macroscopic (bulk) properties. • When the fundamental properties such as pressure, volume, temperature, number of moles and composition have definite values, the system is said to be in any definite state. • When … Read more
Definition of Thermodynamic Terms and Types of System Introduction to Thermodynamics Thermodynamics is formed by combination of two Greek words – ‘therme‘ and ‘dynamikos‘. The word ‘therme’ means “heat” and ‘dynamikos’ stands for “power or motion”. i.e., the flow of heat is called thermodynamics Definition of Thermodynamics The branch of physical chemistry that deals with … Read more
Structure of Liquids The structure of liquids is less well established than that of gases or solids. To understand the structure of liquids, we will consider the theories of liquid state and other various approaches. 1.  Vacancy Theory of Liquids A Liquid is generally less dense than the corresponding solid; \(\implies\) intermolecular space in a … Read more
Introduction to the Liquid State Difference between solid, liquid and gas Solids • Closely packed ordered arrangement of particles (atoms, molecules, ions) • Intermolecular forces of attraction are very strong. • Definite shape (because molecules in solid are strongly held and cannot move) • Definite Volume • Low K.E. i.e., only vibrate about their mean … Read more
 liquefaction of gases For liquefaction of gases having fairly high critical temperature e.g. ammonia, chlorine, sulphur dioxide and carbon dioxide, the application of a suitable pressure alone is sufficient. For liquefaction of permanent gases which have very low critical temperature e.g. hydrogen, oxygen, nitrogen, helium etc. application of pressure alone will not bring liquefaction but … Read more
The Law of Corresponding States In 1881, van der Waals showed that if pressure, volume and temperature of a gas are expressed in terms of its critical pressure, critical volume and critical temperature, then we can obtain an important generalization, viz., known as the law (principle) of corresponding states. The Law of corresponding states can … Read more
Critical Compressibility Factor (\({Z}_c\)) The critical Compressibility factor \({Z}_c\) of a van der Walls gas is given by, \({Z}_c=\frac{{P}_c{V}_c}{R{T}_c}\)Â Â Â Â Â Â Â Â Â Â Â (1)Â Â Â Â Â As we know, $${P}_c=\frac{a}{27{b}^2}$$ $${V}_c=3b$$ $${T}_c=\frac{8a}{27Rb}$$ By putting the value of \({P}_c, {V}_c\) and \({T}_c\)Â in equation 1 : $$\Rightarrow{Z}_c=\frac{(\frac{a}{27{b}^2})(3b)}{{R}[\frac{8a}{27Rb}]}$$ $$\Rightarrow{{Z}_c=\frac{3}{8}}$$ $$\Rightarrow\fbox{\({Z}_c\)=0.375}$$ Note- We can test whether a gas behaves as a van der Waals gas … Read more
