Answer the question in the picture( 19 A)
Answers
General relation between K_p and K_c :
n = Total number of moles of the products - total number of moles of reactants
K_p / K_c = (RT)^n
==================== DERIVATION
Suppose that we had initially 2X moles of SO3. At equilibrium we have X-2+2+1 = X+1 moles. Let the volume of the mixture be V liters. T = 700K. Assuming ideal gas behavior,
P V = n R T => Total pressure P = (X+1) R T/V
2 SO3 (g) <==> 2 SO2 (g) + O2 (g), T = 700 K, K_p = 1.8 * 10^-5 bar
X-2 2 1 moles
K_c = ? per liter.. K_p = [SO2]^2 [O2] / [SO3]^2
Partial pressure of SO3 = (X-2)/(X+1) * P = (X-2) RT/V
Partial pressure of SO2 = 2/(X+1)*P = 2 RT/V
Partial pressure of O2 = RT/V
K_p = 4 R^2 T^2/V^2 * RT / V * V^2 /[(X-2)^2*R^2 T^2]
= 4 RT /[ V (X-2)^2 ] pressure units
Concentration equilibrium constant is defined in terms of molarity ?
Concentration of SO3 : (X-2)/V Molar
Concentration of SO2: 2/V moles/litre
Concentration of O2: 1/V moles/litre
K_c = (2/V)^2 * (1/V) * V^2/(X-2)^2
= 4 / [ V * (X-2)^2 ] volume^-1 units
K_c / K_p = 1 / (R T)
K_c = K_p /(R T) = 1.8 *10^-5 /(8.314 * 700) = 3.093 * 10^-9 /m^3
= 3.093 * 10^-6 /Litre