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 Isotherms of van der Wall’s Equation As we know, the Vanderwaals equation for one mole of gas is, \( \left( {P + \frac{{a}}{{V^2 }}} \right)\left( {V – b} \right) = RT \) ⇒\(PV+\frac{a}{V}-Pb-\frac{ab}{V^2}=RT\) Multiplying both sides by \(\frac{V^2}{P}\) and arranging the obtained equation in decreasing powers of V, we get \(\fbox{\(V^3-(b+\frac{RT}{P})V^2 +\frac{aV}{P} -\frac{ab}{P}=0\)}\) viz., … Read more
Critical Temperature Critical Pressure Critical Volume and their Determination THE CRITICAL PHENOMENON • According to kinetic theory of gases, the gas molecules are constantly moving. ∴ the gas molecules possess kinetic energy. • average kinetic energy of the molecules is directly proportional to the absolute temperature. • Average K.E \(\propto\) absolute temperature. i.e., As the temperature decreases, the kinetic … Read more
Explanation of Behaviour of Real Gases Using Vander Waal’s Equation As we know the Van der Walls equation for n moles of a real gas is, \( \left( {P + \frac{{an^2 }}{{V^2 }}} \right)\left( {V – bn} \right) = nRT \) For one mole of gas, put n=1, \( \left( {P + \frac{{a}}{{V^2 }}} \right)\left( … Read more
Application of Vanderwaals Equation in Calculation of Boyle’s temperature Consider the Z vs P plots of nitrogen at different temperatures varying between – 70°C and 50 °C • The graph shows that as the temperature is raised, the dip in the curve becomes smaller and smaller. At 50°C the curve is almost horizontal for an … Read more
Derivation of Vander Waals equation of State or Equation of State for Real (Imperfect) Gases Many attempts have been made in order to get an equation of state viz. applicable to real gases. A number of equations of state have been suggested to describe the P-V-T relationship in case of real gases. The Van-der-Waals equation … Read more
Collision Diameter, Collision Number, Collision Frequency and Mean Free Path 1. Collision diameter : collision diameter is defined as the closet distance of approach between the centres of the two molecules taking part in a collision. It is denoted by σ. Although the interactions of molecules in a gas are very complicated but here we … Read more
Calculation of Root Mean Square Velocity, Average Velocity and Most Probable Velocity On the basis of kinetic theory of gases, there are three different types of velocities : 1. Average velocity (v) : • The arithmetic mean of the different velocities of all the molecules present in a given gas is called as average velocity. … Read more
Maxwell’s Distribution of Velocities and Energies Maxwell’s Distribution of Molecular Velocities Actually, as a result of collisions, a redistribution of both velocity and energy takes place. • But for convenience, it was supposed that all molecules in a given gas at a given temperature were moving with a constant root-mean-square velocity u. By utilizing probability … Read more
