Chapter 18 - Reaction Rates and Equilibrium Flashcards
How can you express the rate of a chemical reaction?
Change in the amount of reactants of product per unit of time.
What is a rate?
It’s a measure of how much something changes within a specified amount of time.
Define activation energy.
The minimum energy that colliding particles must have in order to react.
List the four factors that can influence the rate of a chemical reaction.
- Temperature
- Concentration
- Particle size/agitation
- Catalysts
What is chemical equilibrium?
It is when the rate of the forward reaction and the reverse reaction are equal. Review establishing equilibrium pg. 610
What happens to the amounts of reactants and products after a reaction has reached chemical equilibrium.
Since chemical equilibrium is a dynamic state, both the forward and reverse reactions continue, but because their rates are equal, no net change occurs in the concentration of reaction components.
What is equilibrium position?
The concentration of reactants and products at equilibrium.
What is Le Chatelier’s principle?
If stress is applied to a system in dynamic equilibrium, the system changes in a way that relieves the stress.
List three stresses that can upset the equilibrium of a chemical reactions.
- Change in concentration
- Change in temperature
- Change in pressure
Define free energy
The energy that is available to do work.
List the 2 characteristics spontaneous reactions share.
- Producing large amounts of product
- Releasing free energy
What does the law of disorder state?
The natural tendency is for systems is to move in the direction of increasing disorder (entropy).
How can you use entropy to determine whether a chemical reaction is more or less likely to be spontaneous?
Reactions in which entropy increases as reactants form products are more likely to be favored. (Spontaneous).
What 2 factors determine the spontaneity of a chemical reaction?
- Size and direction of enthalpy changes
- Entropy changes
When the Gibbs free energy change for a process is (-), what does this tell you about the process?
It’s spontaneous.
If enthalpy increases and entropy increases as well, is the reaction spontaneous?
Only if the unfavorable change in enthalpy is offset by the favorable change is entropy.
If the enthalpy decrease and the entropy decreases as well, is the reaction spontaneous?
Only if the unfavorable entropy change is offset by the favorable enthalpy change.
Which way will the equilibrium position shift if the pressure is increased?
It will want to decrease the pressure and in order to do that it must increase the volume - that is shift to the side with less molecules.
Which way will the equilibrium position shift if the pressure was decreased?
It will want to increase the pressure and in order to do that it must decrease the volume - that is shift to the side with more molecules.
Which way will the equilibrium shift if there was an increase in the concentration of a product?
It will shift to the reactants’ side.
Which way will the equilibrium shift if there was a decrease in a product’s concentration?
It will shift to the products’ side.
Which way will the equilibrium position shift if you were to add heat?
Heat can be considered to be a product/reactant depending on the chemical equation. If heat is added, the equilibrium will shift to the reactants’ side.
Which way will the equilibrium position shift to if heat is removed? (Considering it’s a product)
It will shift to the products’ side if heat is considered to be a product.
What is a catalyst?
It’s a substance that increases the rate of a reaction without being used up during the reaction. They allow reactions to proceed along a lower energy path.
What is Gibbs Free Energy?
