Question

a). Consider the following reaction where K_c = 10.5 at 350 K:
2 CH₂Cl₂(g) -->CH₄(g) + CCl₄(g)
A reaction mixture was found to contain 1.26×10^-2moles of CH₂Cl₂(g), 2.60×10^-2moles of CH₄(g), and 4.42×10^-2moles of CCl₄(g), in a 1.00 liter container.
Indicate True (T) or False (F) for each of the following:
___TF 1. In order to reach equilibrium CH₂Cl₂(g) must be produced .
___TF 2. In order to reach equilibrium K_c must decrease .
___TF 3. In order to reach equilibrium CH₄must be consumed .
___TF 4. Q_c is greater than K_c.
___TF 5. The reaction is at equilibrium. No further reaction will occur.

B) Consider the following reaction where K_p = 9.52×10^-2 at 350 K:  
CH₄(g) + CCl₄(g) -->2CH₂Cl₂(g)  
If the three gases are mixed in a rigid container at 350 K so that the partial pressure of each gas is initially one atm, what will happen?
Indicate True (T) or False (F) for each of the following:
___TF 1. A reaction will occur in which CH₂Cl₂(g) is consumed.
___TF 2. K_p will increase.
___TF 3. A reaction will occur in which CH₄ is consumed.
___TF 4. Q is greater than K.
___TF 5. The reaction is at equilibrium. No further reaction will occur.

C) Consider the following reaction where K_c = 154 at 298 K:  
2NO(g) + Br₂(g) -->2NOBr(g)  
A reaction mixture was found to contain 2.37×10^-2 moles of NO(g), 4.02×10^-2 moles of Br₂(g) and 7.81×10^-2 moles of NOBr(g), in a 1.00 Liter container.
Indicate True (T) or False (F) for each of the following:
___TF 1. In order to reach equilibrium NOBr(g) must be consumed.
___TF 2. In order to reach equilibrium K_c must decrease.
___TF 3. In order to reach equilibrium NO must be consumed.
___TF 4. Q_c is greater than K_c.
___TF 5. The reaction is at equilibrium. No further reaction will occur.

Answer 1

A) first we find Qc for the reaction mixture

and we are given that Kc = 10.5

Since Qc < Kc, to reach equillibrium Qc has to increase

For this to happen either [CH₄] should increase or [CCl₄] should increase or [CH₂Cl₂] should decrease

Therefore 1 is false as increased production of CH₂Cl₂ will decrease Qc

2 is true bacause to reach equillibrium Qc = Kc. As Qc < Kc, either Qc should increase or Kc should decrease.

3 is false beacause consumption of CH₄ willdecrease [CH₄] which will decrease Qc

4 is false becasue Qc = 7.23 and Kc=10.5 therefore Qc < Kc

5 is false becasue Qc is not equal to Kc and therefore the system is not in equillibrium

B) The Qp for the reaction is given by following

Q_P > K_P

Qp should decrease to reach equillibrium

Therefore to reach equillibrium either   should decrease should increase or should increase

1 is True because as CH₂Cl₂ is consumed will decrease which will decrease Q_P

2 is False because Kp changes with temperature only and  temperature is constant kept at 350 K

3 is False because if CH₄ is consumed will decrease which will further increase Q_P

4 is True becasue Q_P = 1 and K_P = 9.52 x 10^-2

5 is False because Q_P is not equal to K_P, therefore system is not in equillibrium

C) First we find Qc, which is given by

As Qc > Kc the reaction is not at equillibrium. Furthermore, to reach equillibrium Qc should decrease.

This can happen if either [NOBr] decreases or [NO] increases or [Br₂] increases

1 is True because when NOBr is consumed [NOBr] will decrease and Qp will also decrease

2 is False beacasue Qc > Kc. Therefore Kc must increase to reach equillibrium

3 is False because if NO is consumed [NO] will decrease which will further increase Qc

4 True as Qc = 270 and Kc = 154

5 False as Qc is not equal to Kc