In which direction does the equilibrium shift for the following reaction?
SO2(g) + NO2 (g) <-> SO3(g0 + NO(g) + 42 KJ
a. temperature increases
b. pressure increases
c. [SO2] increases
d. [NO2] increases
e. temperature decreases
f. [No] increases
Im confused on knowing which way it would shift. thanks!
Le Chatelier's Principle sounds so great when we spit that out in the classroom. When done really right it sounds so esoteric; so learned. Unfortunately, many students don't understand what is going on. So here is a very common way of saying it. It doesn't sound as nice BUT it tells you how to answer these things. Here it is in a nutshell. When we do something to a system in equilibrium it will undo what we've done. Simple, huh? Here's how it works with the first one.
The system is exothermic. It gives off heat when it reacts. So if we increase the temperature it will try to undo that. How can it do decrease the temperature? By shifting to the left BECAUSE when it moves to the left it users up some of the heat we added.
Next, SO2 is increased. So we add SO2 and it tries to decrease SO2. How can it do that? By shifting to the right, it uses up some of the SO2 we've added. That means, of courser, that SO3 is increased, NO is increased, and heat is increased. It also means NO2 is decreased because it uses NO2 when the forward reaction occurs.
Last one. Pressure is increased. You can go through this the same way but the easy way is a modification that I see used all the time. Pressure increase shifts the equilibrium to the side with the fewer mols OF GAS. In this case there are two mols gas on the left and two mols gas on the right; therefore a change in pressure (up or down) will not change the equilibrium. I'll leave the others for you.
Thanks, your explanation was a great help!
To determine the direction in which the equilibrium shifts for a reaction, you need to consider Le Chatelier's principle. According to this principle, if a change is applied to a system at equilibrium, the system will try to counteract that change to establish a new equilibrium.
Let's analyze each change mentioned in the options to see how it would affect the equilibrium:
a. Temperature increases: In this case, the equilibrium will shift in the endothermic direction to absorb the added heat. Since the reaction is exothermic (it releases energy), the forward reaction is favored, and thus, the equilibrium will shift to the right (forward).
b. Pressure increases: The reaction does not involve any gases in different stoichiometric coefficients. Therefore, changing the pressure would have no effect on the equilibrium shift.
c. [SO2] increases: By increasing the concentration of SO2, the system will shift in the direction that consumes this reactant. According to the balanced equation, increasing the concentration of SO2 would shift the equilibrium to the right (forward).
d. [NO2] increases: Increasing the concentration of NO2 will favor the reaction that consumes this reactant. Thus, the equilibrium will shift to the right (forward).
e. Temperature decreases: In this case, the equilibrium will shift in the exothermic direction to release heat. Since the reaction is exothermic, the reverse reaction is favored, and thus, the equilibrium will shift to the left (reverse).
f. [NO] increases: Increasing the concentration of NO will favor the reaction that consumes this reactant. Consequently, the equilibrium will shift to the left (reverse).
From the analysis above, the equilibrium will shift to the right (forward) for options a, c, and d. Hence, the correct answers are a, c, and d.