Question

Le Chantelier: Concentration

Consider the following system at equilibrium where H=-16.1 kJ, and Kc=154, at 298 K.

2NO(g) + Br2(g) 2NOBr(g)

When 0.36 moles of Br2(g) are added to the equilibrium system at constant temperature:

the value of Kc A.increases

                         B. decreases

                          C. remains the same.

the value of Qc A. is greater than Kc

                           B. is equal to Kc

                            C. is less than Kc

the reaction must: A. run in the forward directin to restablish equilibrium

                             B. run in the reverse direction to reestablish equilibrium.

                             C. remain the same. It is already at equilibrium.

the concentration of NO will: A. increase

                                              B. decrease

                                              C. remain the same.

Answer 1

2NO(g) + Br2(g) --------------> 2NOBr(g)   ,   H =-16.1 kJ, and Kc = 154

When 0.36 moles of Br2(g) are added to the equilibrium system at constant temperature:

the value of Kc : C.) remains the same.

the value of Qc : C) . is less than Kc

the reaction must: A) . run in the forward directin to restablish equilibrium

the concentration of NO will: B.) decrease

Explanation :

Kc only change with temperature.

if 0.36 mol Br2 increases , the reaction shift to forward direction.

so the concentration of NO and Br2 decreases, and NOBr increases.

then Qc decreases.