Question

** ANSWER FAST I WILL MARK YOU BRAINLIEST AND GIVE 20 POINTS * * THIS IS A CHEMISTRY QUESTION SO PLEASE ONLY ANSWER IF YOU ARE GOOD AT CHEMISTRY *
A certain reaction is endothermic in the forward direction and has a greater number of molecules on the product side. Which set of conditions should be used to maximize the yield of the products?

A. Decrease the temperature and decrease the pressure.
B. Increase the temperature and decrease the pressure.
C. Decrease the temperature and increase the pressure.
D. Increase the temperature and increase the pressure.

Answer 1

Answer:

$\boxed{\text{ B. Increase the temperature and decrease the pressure.}}$

Explanation:

Let's say the reaction is

R ⇌ 2P; endothermic

I like to consider heat as if it were a reactant or a product in a chemical equilibrium.

Another way to write the equilibrium would be

heat + R ⇌ 2P

According to Le Châtelier's Principle, when a stress is applied to a system at equilibrium, the system will respond in a way that tends to relieve the stress.

Let's consider each of the stresses in turn.

(i) Changing the temperature

If you want to increase the amount of product, you increase the temperature. The system will try to get rid of the added heat by shifting to the right, thus forming more product.

(ii) Changing the pressure

If R and P are liquids or solids or in aqueous solution, changing the pressure will have no effect. Something must be in the gas phase for a change in pressure to affect the position of equilibrium.

If P is a gas, the equilibrium is

heat + R ⇌ 2P(g)

Then, decreasing the pressure will produce more P. If you reduce the pressure, the system will respond by shifting to the right (the side with more gas molecules) to produce more P and bring the pressure back up