Br2(l)+Cl2(g) (double arrow) 2BrCl(g)

dH=+29.4 kJ/mol

I am having trouble understanding this. Will the system shift left, right, or unchanged and why?

a.Increasing Temp.
b. Increasing pressure in flask by adding Ar.
c. Increasing volume of flask
d. Adding Br2(l)...is answer move right
e. Removing Cl2(g)...is " left?
f. Adding BrCl(g)...is " left?
g. Adding catalyst

It's easy to understand if you look at it this way. Le Chateier's Principle tells us that when a stress is added to a system in equilibrium, the system will shift so as to undo what we've done to it.

The equation tells you that heat is given off when it reacts left to right. I might rewrite the equation as this to emphasize that.
Br2(l)+Cl2(g)<==>2BrCl(g) + HEAT

So if the system adds heat in reacting from left to right and we add more heat, the system will try to get rid of the excess heat we've added. So it will shift to the left meaning that if the reaction goes from right to left it USES up the heat. right?
b. In pressure problems of this kind it shift to the side with fewer mols (of gas). In this case it will not shift because both sides contain 2 moles.
c. For volume changes just convert to what that means with pressure. For example increasing volume means pressure is decreased and now revert to counting mols.
d is right
e is right
f is right
g. A catalyst NEVER shifts the equilibrium but it does change the rate of the reaction.

a. Increasing Temp:

When the temperature is increased, it favors the endothermic reaction because it is exothermic in the forward direction. Therefore, the system will shift to the right to consume the added heat. The answer is "move right."

b. Increasing pressure in the flask by adding Ar:
Increasing pressure has no effect on the position of the equilibrium because there are no gases added or removed from the reaction. Thus, the system will remain unchanged. The answer is "unchanged."

c. Increasing volume of the flask:
Increasing the volume decreases the pressure. Since the reaction has fewer moles of gas on the reactant side (Br2, Cl2) compared to the product side (2BrCl), increasing the volume will favor the side with more moles of gas, namely the product side. Hence, the system will shift to the right. The answer is "move right."

d. Adding Br2(l):
Adding more Br2 will increase its concentration, shifting the equilibrium to consume the excess reactant. Since Br2 is on the reactant side, the system will shift to the right. The answer is "move right."

e. Removing Cl2(g):
Removing Cl2 reduces its concentration, which results in a decrease in the rate of the reverse reaction. To compensate for the loss of Cl2, the system will shift to the left to produce more of Cl2 and maintain equilibrium. The answer is "move left."

f. Adding BrCl(g):
Adding BrCl does not directly affect the concentration of either reactants or products since it is already one of the products. Therefore, the addition of BrCl does not cause a shift in equilibrium, and the system will remain unchanged. The answer is "unchanged."

g. Adding a catalyst:
A catalyst does not affect the position of the equilibrium. It only increases the rate of both the forward and reverse reactions, but it does not shift the equilibrium. Hence, the system will remain unchanged. The answer is "unchanged."

To understand whether the system will shift left (backward), right (forward), or remain unchanged, we need to consider Le Chatelier's principle. This principle states that when a system at equilibrium is put under stress, it will shift in a way that alleviates that stress.

Let's analyze each of the given scenarios:

a. Increasing temperature:
Increasing the temperature would cause the system to shift in the endothermic direction to consume heat. Since the reaction is endothermic (+29.4 kJ/mol), the system would shift right to produce more products (BrCl).

b. Increasing pressure in the flask by adding Ar:
Pressure is related to the concentration of gas molecules. Adding an inert gas like Ar does not affect the concentrations of the reacting species (Br2, Cl2, BrCl), so the system would remain unchanged.

c. Increasing the volume of the flask:
Increasing the volume of the flask decreases the pressure. Following Le Chatelier's principle, the system would shift in the direction that increases the pressure. In this case, the system would shift to the left to decrease the number of moles of gas and therefore increase the pressure.

d. Adding Br2(l):
Adding more Br2 increases the concentration of reactant Br2. This would cause the system to shift right to consume the additional reactant and produce more product BrCl.

e. Removing Cl2(g):
Removing Cl2 decreases the concentration of reactant Cl2. According to Le Chatelier's principle, the system would shift right to replenish the decrease in Cl2 by breaking more Br-Cl bonds and producing more BrCl.

f. Adding BrCl(g):
Adding BrCl increases the concentration of the product BrCl. Le Chatelier's principle predicts the system would shift left to reduce the concentration of the added product and reach a new equilibrium.

g. Adding a catalyst:
A catalyst does not affect the position of the equilibrium. It speeds up the rate at which the reactants are converted to products, but the equilibrium composition remains unaffected. Therefore, the system would remain unchanged.

In summary:
a. Shift right
b. No change
c. Shift left
d. Shift right
e. Shift right
f. Shift left
g. No change