If `D_(T)and D_(o)` are the theoretical and observed vapour densities at a definite temparature and `alpha` be the degree of dissocition of a substance ,then ,`aplha` in the terms of `D_(o),D_(T)` and n (number of moles of products formed formed from 1 mole reactant ) is calculated by the formula :

If D_(T)and D_(o) are the theoretical and observed vapour densities at a definite temperature and alpha be the degree of dissociation of a substance ,then , alpha in the terms of D_(o),D_(T) and n (number of moles of products formed from 1 mole reactant ) is calculated by the formula :

Consider the following hypothetical equilibrium 2B(g)hArrB_(2)(g) If d is observed vapour density and D is theoretical vapour density, then degree of association (alpha) will be

Consider the following hypothetical equilibrium 2B(g)hArrB_(2)(g) If d is observed vapour density and D is theoretical vapour density, then degree of association (alpha) will be

The vapour density of N_(2) O_(4) at certain temperature is 30 . What is the percentage dissociation of N_(2) O_(4) at that temperature ? [Hint : alpha = (D - d) // d ( n - 1) ]

The equation alpha=(D-d)/((n-1)d) is correctly matched for: ( alpha is the degree of dissociation, D and d are the vapour densities before and after dissociation, respectively).

The equation alpha=(D-d)/((n-1)d) is correctly matched for: ( alpha is the degree of dissociation, D and d are the vapour densities before and after dissociation, respectively).

Properties, whose values depend only on the concentration of solute particles in solution and not on the identity of the solute are called colligative properties.there may be change in number of moles of solute due to ionisation or association hence these properties are also affected.Number of moles of the product is related to degree of ionisation or association by van Hoff factor 'i' given by i=[1+(n-1)alpha] for dissociation where n is the number of products (ions or molecules ) obtained per mole of the reactant. & i=[1+(1/n-1)alpha] for association where n is number of reactant particles associated to give 1 mole product.A dilute solution contains 't' moles of solute X in 1 kg of solvent with molal elevation constant K_b .The solute dimerises in the solution according to the following equation.The degree of association is alpha . 2X hArr X_2 The colligaive properties observed will be