Chemical Kinetics Flashcards
What is Rate of a Reaction?
This is the change in concentration of reactant per unit
time
It is fastest at the beginning and slowest at
the end
How does concentration of the reactants effect reaction rate
The more molecules present in the container, the more frequently they collide and the more often a reaction between them occurs
The higher the concentration of reactants, the faster the reaction.
How doesthe physical nature of reactans effect reaction rate?
-When the reactants are in the
same phase they mix more easily hence more frequent collision.
-When they are in different phase, contact occur only at the interface, so vigorous
stirring or grinding maybe needed faster reaction
How does change in pressure effect the reaction rate?
A change in pressure has the same effect as changing concentration- a higher pressure compresses the mixture of gases and increases the concentration
How does surface are effect rate of reaction?
Increase in surface area of reactants(solids) speeds up the rate of reaction
How does a catalyst effect rate of reaction?
it speeds up the rate of chemical reaction without themselves changing permanently
How does temperature effectrate of reaction
Increasing the temperature increases the reaction rate by increasing the number and energy of collisions.
Rate α collision energy α temperature
More collisions occur in a given time at higher temperature. The temperature affects the kinetic energy of the molecules and thus the energy of the
collision
Express rate law of the general reaction: aA + bB → cC + Dd
Rate = K [A]ᵐ[B]ⁿ
What is reaction order?
The exponent to which the concentration of a reactant is raised in the rate law of a chemical reaction
What is a first order reaction
A reaction where the rate is directly proportional to the concetration.
Rate = k[A]
What is a second order reaction
A reaction where the rate is directly proportional to the square of the concetration
Rate = k[A]²
What is a zero order reaction
A reaction where the rate is not dependent on the concetration
Rate= k[A]⁰
Rate = k[1]
Rate = k
What are elemetry reactions?
The individual steps, which together make up a proposed reaction mechanism
What is the rate determining step
The slowest step in a reaction
if a reactant appears in the rate determining step, then the concentration of that reactant will appear in rate equatio
