Le Chatelier's Principle and Reaction Quotients

The video tutorial explains Le Chatelier's Principle, which states that if a stress is applied to a reaction mixture at equilibrium, the net reaction will shift in the direction that relieves the stress. The tutorial uses a hypothetical reaction to demonstrate how changes in reactant concentration affect equilibrium. It also covers the synthesis of ammonia, showing how increasing hydrogen concentration shifts the reaction to the right, increasing ammonia production. The video concludes with a discussion on how changes in reactant or product concentrations can shift reactions either to the right or left to re-establish equilibrium.

What does Le Chatelier's Principle predict when a stress is applied to a system at equilibrium?

• The reaction will reverse completely.

• The reaction will speed up indefinitely.

• The reaction will proceed in the direction that relieves the stress.

• The reaction will stop.

In the hypothetical reaction where gas A turns into gas B, what is the equilibrium constant (Kc) at 25 degrees Celsius?

• 3

• 4

• 2

• 1

What happens to the reaction quotient (Qc) when the concentration of reactant A is increased?

• Qc becomes zero.

• Qc becomes greater than Kc.

• Qc becomes less than Kc.

• Qc remains equal to Kc.

After increasing the concentration of reactant A, in which direction does the net reaction proceed to re-establish equilibrium?

• It oscillates back and forth

• To the right

• It remains unchanged

• To the left

Why is it useful to calculate Q values in Le Chatelier's Principle problems?

• To determine the speed of the reaction

• To calculate the pressure of the system

• To predict the direction of the net reaction

• To find the temperature of the reaction

In the synthesis of ammonia, what happens to the concentration of ammonia when hydrogen concentration is increased?

• It increases

• It remains constant

• It decreases

• It becomes zero

What is observed on the graph when the concentration of hydrogen is increased in the ammonia synthesis reaction?

• A sudden increase in temperature

• A sudden decrease in nitrogen concentration

• A sudden increase in hydrogen concentration

• A sudden decrease in ammonia concentration

According to Le Chatelier's Principle, what happens if the concentration of a product is increased in a reaction at equilibrium?

• The reaction stops

• The reaction speeds up

• The reaction shifts to the right

• The reaction shifts to the left

What is the effect on the net reaction if the concentration of a reactant is decreased?

• The reaction shifts to the left

• The reaction shifts to the right

• The reaction stops

• The reaction remains unchanged

In the context of Le Chatelier's Principle, what does a constant concentration of reactants and products indicate on a graph?

• The reaction is speeding up

• The reaction is at equilibrium

• The reaction has stopped

• The reaction is slowing down