For the gaseous equilibrium represented below, it is observed that greater amoun
ID: 528221 • Letter: F
Question
For the gaseous equilibrium represented below, it is observed that greater amounts of PC1_3 and Cl_2 are produced as the temperature is increased. What is the sign of delta S^+ for the reaction? Explain. What change, if any, will occur in delta G+ for the reaction as the temperature is increased? Explain your reasoning in terms of thermodynamic principles. If the volume of the reaction mixture is decreased at constant temperature to half the original volume, what will happened to the number of moles of C_2 in the reaction vessel? Explain.Explanation / Answer
PCl5 (g) ------------> PCl3 (g) + Cl2 (g)
No.of gas reactants = 1
No.of gas products = 2
SInce it is given that the amount of products increases with temperature, the forwards reaction is endothermic.
(a)
Since moving from left ot right there is increase in number of gas substances, entropy of the system increases.
deltaS = + ve
(b)
SInce the amount og products increases with increase in temperature, the equilibrium constant value also increases.
Kp = PProducts / Preactants
And we know, deltaG0 = - R T lnKp
As Kp increases, the deltaG0 value will be more negative indicating more spontaneous.
(c)
According to Lechatlier's principle, decreases in volume shifts the shifts the equilibrium towards that side which occupies less volume i.e which has less number of gas substances. In this case towards left side.
Hence the number of moles of Cl2 will decrease.