Consider the following system at equilibrium where delta H degree = -198 kJ/mol,
ID: 532110 • Letter: C
Question
Consider the following system at equilibrium where delta H degree = -198 kJ/mol, and K_c = 34.5 at 1150 K. 2 SO_2 (g) + O_2 (g) 2 SO_3 (g) When 0.37 moles of SO_3 (g) are added to the equilibrium system at constant temperature: the value of K_c A. increases. B. decreases. C. remains the same the value of Q_c A. is greater than K_c. B. is equal to K_c. C. is less than K_c. the reaction must: A. run in the forward direction to reestablish equilibrium. B. run in the reverse direction to reestablish equilibrium. C. remain the same, It is already at equilibrium. the concentration of O_2 will: A. increase. B. decrease C. remain the sameExplanation / Answer
for the given reaction, 2SO2(g)+ O2(g) <----> 2SO3(g)
Kc= [SO3]2/ [SO2]2 [O2] =34.5, where [SO3], [O2] and [SO2] are concentrations at equilibrium,
Equilibrium constant is a function of temperatrue only
1. Hence when 0.37 moles of SO3 is added, it does not have any effect on Equilibrium constant
however, Q= reaction coefficient = [SO3]2/ [SO2]2 [O2] increases. since [SO3] increases due to addition of moles of SO3, QC>K
since QC>K the reaction proceeds as to increase [SO2] and [O2]. So the reaction proceeds in the backward direction, i.e toward reactants side.
This leads to an increased concentration of O2.