chemistry

​Factors affecting chemical equilibrium

​How does Le Chatelier's principle apply to equilibrium systems?

​ Which various factors affect chemical equilibrium?

​Essential questions...

​Le Chatelier's Principle

​A change in one of the variables that describe a system at equilibrium produces a shift in the position of the equilibrium that counteracts the effect of this change.

Multiple Choice

What is le Chatelier's Principle?

• keeping the same variables that describe a system at equilibrium produces a shift in the position of the equilibrium that counteracts the effect of this change.

• ​A change in one of the variables that describe a system at equilibrium produces a shift in the position of the equilibrium that counteracts the effect of this change.

• ​A change in one of the variables that describe a system at equilibrium produces a shift in the position of the equilibrium that does not counteracts the effect of this change.

​Applying Le Chatelier's Principle

​Adjusting the concentrations of either the reactants or the products puts a stress on the equilibrium. Earlier, you read about collision theory, which states that particles must collide in order to react. The number of collisions between reacting particles depends on the concentration of the particles, so perhaps the chemist can change the equilibrium by changing concentrations.

​Addition of the reactants

Suppose additional carbon monoxide was injected into the reaction vessel, raising the carbon monoxide concentration from 0.30000 M to 1.00000 M. A higher concentration of carbon monoxide immediately increases the number of effective collisions between carbon dioxide and H2 molecules and upsets the equilibrium. The wing reaction rate increases, as indicated by the longer arrow to the right.

Multiple Choice

Adding to the reactant makes

• the equilibrium constant

• the equilibrium shift to the right

• the equilibrium shift to the left

​Removing Products

Suppose that instead of injecting more reactants, the chemist decides to remove a product (H2O) by adding a desiccant to the reaction vessel. Remember that a dryer is a material that absorbs water. What does Le Chatelier's principle predict that the equilibrium will do in response to a decrease in water concentration? The equilibrium shifts in the direction that tends to re-focus the water again. That is, the equilibrium shifts to the right and an additional product is produced

Multiple Choice

Removing the products

• shifts to the right

• shifts to the left

• stays constant

​Adding products

Le Châtelier's principle predicts that if an additional product is added to a reaction at equilibrium, the reaction will shift to the left. Stress is relieved by turning products into reactants If one of the reactants is removed, a similar shift to the left will occur.

​Solve Check My understanding 1

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