equilibrium

This symbol indicates that a reaction is _____

• reversible

• irreversible

Around what time does the reaction reach equilibrium?

• 25 min

• 70 min

• 45 min

• 80 min

What are the two factors that help determine that equilibrium is reached?

• Forward reaction rate is faster than the reverse and the concentrations are equal

• Forward and reverse reaction rates are equal and concentrations are equal

• Forward and reverse reaction rates are equal and concentrations are constant

Why does the rate of the reaction decrease over time?

• Exothermic reactions lose heat which cools the reaction which decreases reaction rate.

• As the reaction proceeds, the concentration of the products results in fewer collisions

• As the reaction proceeds, a decrease in the concentration of reactants results in fewer successful collisions.

• Not all molecules will react and some choose to stay in their present form

Which of the following is TRUE for a system that is in dynamic equilibrium?

• The forward reaction goes to 100% completion.

• The reaction rate of the forward reaction approaches zero.

• The concentration of products is equal to the concentration of the reactants.

• none of the above

When writing the expression for an equilibrium constant, which type of substance is included?

• solids

• pure liquids

• gases

• all of the above

Le Chatelier's Principle states that:

• a disturbing force must be applied to a system in order for it to reach equilibrium.

• when a system at equilibrium is disturbed, a new equilibrium constant is established.

• when a chemical system at equilibrium is disturbed, the system shifts in order to minimize the effect.

• when a chemical system is at equilibrium it is no longer possible to alter the system.

If the equilibrium constant is much greater than one (K >> 1) then

• Equilibrium is not established.
• Equilibrium lies to the right (products are favored)
• Equilibrium lies to the left (reactants are favored)
• Neither products or reactants are favored.

N₂O₄(g) ↔ 2 NO₂(g)
What is the concentration equilibrium constant expression?

• K_c = [NO₂]²/[N₂O₄]
• K_c = [N₂O₄]/[NO₂]²
• K_c = [N₂O₄]²/[NO₂]
• K_c = [NO₂]/[N₂O₄]²

Which is the reactant - and why?

• A, as concentration decreases
• B, as concentration decreases
• A, as concentration increases
• B, as concentration increases