Chapter 31 - Chemical Kinetics Flashcards
What is important when studying a chemical reaction?
1) Conditions
2) Mechanism
3) Rate
4) Equilibrium
What is a mechanism? What does it tell us?
A series of steps through which a chemical reaction occurs
- Tells us the rate, position of equilibrium, and thermodynamic characteristics
What is a reaction intermediate?
Part of a reaction that does not appear in the overall reaction because it is not a reactant nor product
- Difficult to detect
What is the rate determining step?
The slowest step in a proposed mechanism because the overall reaction cannot proceed faster than that step
What is the reaction rate?
The change of concentration of a reactant or finished product with respect to time
Rate = k [A]x [B]y
Where x and y are the order of the reaction
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What are reaction orders?
Classification of chemical reactions based on kinestics as zero-order, first-order, second-order, mixed-order, and/or higher-order reactions
What is a zero order reaction?
What is the rate equation?
What is the half-life?
Has a constant rate which is independent of the reactants concentrations
Rate = k
Half Life = 1/2 Ao/ko
What is a first order reaction?
What is the rate equation?
What is the half-life?
Has a rate proportional to the concentration of one reactant
Rate = k[A]
t(1/2) = ln2/k
What is a second order reaction?
Has a rate proportional to the product of the concentration of two reactant or to the square of the concentration of a single reactant
What is a higher-order reaction?
Order greater than two - can be calculated the same way as lower-order reactions but more possible combinations must be considered
What is a mixed-order reaction?
Has a fractional order (unlikely for test day)
What is the collision theory of chemical reactions?
The rate of reactant is proportional to the number of collisions per second between reacting molecules
What is a factor that causes reaction rates to increase?
Temperature
What is an effective collision?
A collision that leads to the formation of products which only occurs if the molecules collide with the correct orientation and sufficient force to break the existing bonds and form new ones
