Soul of Chemistry

Degree of dissociation, mole fraction and associated equilibrium: The number of molecules dissociated out of total number of molecules originally taken is called the degree of dissociation. Mathematically, Degree of dissociation = α = (Number of molecules dissociated / total number of molecules) X 100 It is expressed in percentage or as fraction or decimals. If 40 molecules are dissociated out of 100 molecules than the degree of dissociation is expressed as 40% or 0.4.             The ratio of number of moles of a component to the total number of moles of the entire component in a given system is called the mole fraction. If nA and nB are the numbers of moles of two components A and B of a system then the total number of moles = nA + nB. Thus the mole fraction of component A = xA or XA (read as chi A) = nA / (nA + nB). Similiarly, the molefraction of B = xB or XB = nB / (nA + nB).             The mole fraction of a component multiplied by the total pressure inside a containe

  Skin infections  now a days are very common. Sweating, wrong clothing (use of non cotton dresses),  food habits, chemicals in foods, infected water and foods, weakened immunity and above all the polluted atmosphere are the main causes for this.        As soon as we consult doctors for skin infection, they prescribe medicines, creams, lotions and ointments. The point is, are they safe enough? Are there any natural alternatives without any side effects?         The Answer to the first question is almost NO. Almost Every Allopathic treatment has mild to very severe side effects. My family and relatives have complained the same on using lotions and creams related to skin infections. the pharmaceuticals themselves warn on their products of severe side effects. A few are given below for your consideration. The Common Side effects in using creams like these include: 1. Allergic Skin Reaction 2. Vertigo (head spinning) 3. Change in Blood Pressure 4. irritation 5. Rash 6. Eczema and many more

Le Chatelier’s Principle Statement: Whenever a reversible reaction at equilibrium is subjected to change in any condition like change in pressure, temperature or concentration etc. then the equilibrium shifts itself in such a direction to cancel out the effect and accordingly a new equilibrium state is established. This can be explained taking the example of preparation of ammonia in Haber’s process. What happens when we increase or decrease the pressure or temperature of the reaction vessel or we add more reactant or when we add inert gas? Let us discuss one by one. The reversible reaction is: N 2 + 3H 2 ⇌ 2NH 3 1.       1.     Effect of changing the pressure: a.       When pressures is increased: If we increase the pressure inside a vessel by decreasing the volume, then the equilibrium tries cancel out the effect of change, i.e., the equilibrium tries to decrease the pressure. This is only possible if the total number of molecules inside the vessel decreases. Hence the

Chemical Equilibrium, Equilibrium Constant, Reaction Quotient and Shifting of Equilibrium      Based on the fact that whether a chemical reaction would go for completion or not, the chemical reaction can be divided into two categories. 1. Irreversible reaction:  In these reactions the reactants are completely converted into products and the products formed donot react to give back the reactants. Precipitation or ionic, neutralisation, redox, combustion and decomposition reactions come under this category. 2. Reversible reaction: These reactions take place in both the directions under similar conditions of temperature and pressure. Example:  1. N2 (g) + 3H2 (g)    ⇌    2NH3 (g) 2. 3Fe (s) + 4 H2O (g)  ⇌  Fe3O4 (s) + 4 H2 (g) Characteristics of reversible reaction: 1. Proceed in both directions, the forward and backward. 2. Take place in closed vessel. 3. Reactants and products are separated by double arrow ( ⇌ ) 4. Never proceed to completion 5. An equilibrium is established at the end

Previous Year question papers: North Orissa University CCH CHEM XI