District 9 - Kinetics and Equilibrium

Welcome to your training for how to take down District 9 when you are in the arena. This District breads truly ruthless killers. Not only are they ruthless, but they also kill extremely fast (it helps when you have a catalyst in your back pocket). They are advised by past champion Le Chatlier. Be very cautious when approaching this District, they have been known to make alliances with others and then kill them once the opportunity presented itself.

Past District 9 Champions

  • The crazed Le Chatlier...don't even ask what he did to win his Games

Rates of Chemical Reactions

Chemical kinetics is the study of how reaction rates can be described and altered. A rate describes how fast something changes with time. Rate is measured either by the rate of formation of product or the rate of disappearance of the reactants.

The major theory that helps to describe why chemical reactions occur is known as collision theory. Reactions occur when molecules collide. Therefore, more collisions, a faster overall rate of reaction. Less collisions, a slower rate.




The rate of chemical reaction can be changed by altering the:

  • Temperature
  • Pressure
  • Concentration

Basic overview of collision theory

Collisions are essential for reactions to occur. Therefore, altering concentration, temperature, and pressure impact the rate because of how they impact collisions.

Factors Affecting Rate

Change in Concentration

As you increase the concentration, the rate of reaction increases. The higher the concentration the more collisions that are occurring. This increased amount of collisions results in a faster rate of reaction.

Change in Temperature

As you heat up molecules they begin to move faster. The faster molecules move the more they collide, which means a faster rate. Therefore, as temperature increases, the rate of reaction increases.

Change in Pressure

As you increase the pressure molecules collide more into the wall of the container and into each other. Therefore, as you increase pressure, you increase the rate of the reaction.

Activation Energy and Catalyst

The energy associated with a reaction is extremly important in understanding thermochemistry and chemical kinetics. We can graph the energy that is associated with a reaction using a reaction coordinate. This reaction coordinate cna be used to describe the relationship between the energy of the reactants and products. Additionally, it describes the amount of energy required to carryout a reaction.

Reactions require a certain amount of energy in order to proceed. The activation energy is the amount of energy required to get the reaction to go to completion. We can mesure the activiation energy by looking at the enregy level of the reatants and the top of the hill on a reaction coordinate. The difference between the top of the hill and the energy of the reactants is known as the activation energy.

Reactions can be sped up through the use of catalysts. A catalyst is a substance that speeds up the rate of reaction by lowering the activation energy. Catalysts work by providing an alternative pathway for the reaction to proceed. Catalysts act to speed up the reaction without using up the catalyst.

Reaction coordinate with activation energy labeled

Reaction coordinate with and without a catalyst

Equilibrium

As a reaction moves towards equilibrium the rates of the forward and reverse reaction become equal.

Reactions can proceed in both directions. We can decribe a rate in terms of either the rate of the forward reaction and/or the rate of the reverese reaction. When the rate of the forward reaction becomes equal to the rate of the reverse reaction, we say that the reaciton has achieved equilibrium.

A reaction does not stop when equilibrium is achieved. The rate at which we use products/reactants is the same as the rate at which we produce products/reactions. We call this dynamic equilibrium where the reaction is still occurring, but equilibrium is maintained.

Le Chatelier's Principle

Le Chatelier’s principle states that if we alter something that is on the products or reactants side of an equilibrium, then the system will respond in order to re-establish equilibrium. This principle applies to all reactions in equilibrium.

The major theory that helps to describe why chemical reactions occur is known as collision theory. Reactions occur when molecules collide. Therefore, more collisions, a faster overall rate of reaction. Less collisions, a slower rate.

Change in Concentration:

Reactions like to remain at equilibrium. Therefore, if we add more of a product/reactant, then our reaction will shift to the other side in order to compensate for this new amount.

Change in Temperature:

When a reaction is endothermic, heat is listed as a reactant. When a reaction is exothermic, heat is listed as a product. Therefore we can treat heat like a reactant or a product depending where it is listed. This allows us to know which side heat is added/removed from and, thus, we can determine which way the equilibrium will shift.

Change in Pressure:

For a gas reaction, changes in pressure can alter the side of the reaction that is favored. If we increase pressure, we increase the concentration of all substances, so the reaction will shift to the side that produces less molecules If we decrease pressure, we decrease the concentration of all substances, so the reaction will shift to the side that produces more molecules

Le Chatelier's principle can be thought of as a balancing act. If you add something to one end of the equation, then you need to shift in order to reestablish balance.

Increasing the pressure shifts equilibrium so that a larger concentration of carbon dioxide gas can stay dissolved inside a bottle of soda. This is why they're called carbonated sodas.

Practice!

An Invitation to a Feast!

The Capital is offering a "feast" at sunrise. District 9 is sure to be there. To ensure that you have the feast to yourself, complete the following assessment to kill District 9: SEE ASTOR FOR DISTRICT 9 ASSESSMENT!

Other Useful Resources