Chemical Equilibrium and Reaction Rates Flashcards

Flashcards about Chemical Equilibrium, Le Chatelier's Principle, and Reaction Rates

When is equilibrium reached?

Equilibrium is reached when the concentrations of reactants and products no longer change.

What are reversible reactions?

Reactions that can occur in both the forward and backward directions.

What is the relationship between forward and reverse reaction rates at equilibrium?

The rate of the forward reaction equals the rate of the reverse reaction.

What happens at equilibrium even though concentrations are constant?

The reaction continues to run at equal rates in both directions.

What is the formula for the equilibrium constant (Keq)?

Keq = [C]^c[D]^d / [A]^a[B]^b

What is Le Chatelier's Principle?

If a stress is applied to a system at equilibrium, the system will shift in the direction that relieves the stress.

What happens if the concentration of a substance is increased in a system at equilibrium?

The system will shift away from what was added.

What happens if the concentration of a substance is decreased in a system at equilibrium?

The system will shift towards what was removed.

According to Boyle's Law, what is the relationship between volume and pressure?

A decrease in volume (at constant temperature) leads to an increase in pressure.

How will equilibrium shift if temperature is increased?

Equilibrium will shift away from heat.

How will equilibrium shift if temperature is decreased?

Equilibrium will shift towards heat.

What effect does adding a catalyst have on equilibrium?

Catalysts speed up chemical reactions in both directions, but equilibrium does not shift.

How does concentration affect reaction rates?

Molecules collide more often when they are more concentrated.

How does temperature affect reaction rates?

Greater molecular speeds make a reaction go faster.

List four main ways to increase the rate of a reaction.

Heating substances, using higher concentrations, mixing in a more finely divided form, or adding a catalyst.

What happens to the concentration of reactants over time?

The concentration falls, and at the same time the rate at which the reaction proceeds decreases.

What happens to the concentration of products over time?

The concentration increases, and at the same time the rate at which the reaction proceeds decreases.

How do scientists measure reaction rates?

By finding a characteristic of a product or reactant that can be measured and monitoring the concentration.

What is activation energy?

The amount of energy needed to start a reaction.

What is the role of catalysts in chemical reactions?

Catalysts control which reactions happen and how fast they go without being used up in the process.

What are homogeneous catalysts?

Gases or liquids mixed uniformly with reactants that are also gases or liquids.

What are heterogeneous catalysts?

The catalyst is in one physical form (usually solid) and the reactants are in another (such as gases or liquids).

What are catalysts?

Substances that increase the rate of a chemical reaction while not being altered themselves.

What are inhibitors?

Compounds that slow catalyzed reactions by interfering with how catalysts work or by tying up reactants.

What happens to the concentrations of C6H12O6 and O2 as the reaction proceeds in C6H12O6 (s) + 6 O2(g) → 6 H₂O (g) + 6 CO₂ (g)?

Decrease.

What happens to the concentrations of H2O and CO2 as the reaction proceeds in C6H12O6 (s) + 6 O2(g) → 6 H₂O (g) + 6 CO₂ (g)?

Increase.

According to the collision theory, what circumstances are needed for C6H12O6 & O2 to react?

Correct orientation and enough energy.