CHM 2046C Module 10 Sample Exam

Part E: Experimental Determination of Equilibrium Constants 10 points

Calculate the equilibrium constant at 25^oC for the reaction:

2 NOCl(g) ç è 2 NO (g) + Cl₂

when 2.00 moles of NOCl were placed in a 1.00-L flask, and the concentration of NO after equilibrium was achieved was 0.66 moles/liter.

Part F. Calculations based on K_c 10 points

At 25^oC, K_c=0.090 for the reaction:

H₂O (g) + Cl₂O (g) ç è 2 HOCl (g)

Calculate the concentration of all species if 2.0 mole of pure H₂O and 2.0 mole of pure Cl₂O are placed in a 2.0 L flask and the system is allowed to come to equilibrium.

Part G: LaChatelier’s Principle 10 points

Consider the isomerism of butane with an equilibrium constant of K_c = 2.5.

CH₃

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CH₃-CH₂-CH₂-CH₃ (n-butane) ç è CH₃-CH-CH₃ (isobutane)

The system is originally at equilibrium with [n-butane]=1.0 M and [isobutane]=2.5M.

(a) If 0.50 moles/liter of isobutane is suddenly added and the system shifts to a new equilibrium position, what is the equilibrium concentration of each gas?

(b) If 0.50 moles/liter of n-butane is suddenly added and the system shifts to a new equilibrium position, what is the equilibrium concentration of each gas?