Lesson 11 - Rate Law Flashcards
When is reverse reaction possible?
As soon as product is formed
Initial rate of reaction
When t=0
Equation for rate law
r=k[A] where k is the rate constant in inverse seconds
First order reaction
A reaction that proceeds at a rate that depends linearly on only one reactant concentration. Rate is proportional to the first power of concentration.
Example of first order reaction
Decomposition/Decay reactions
Second order reaction
A reaction that is proportional to the square of the concentration of one reactant. The initial rate increases parabolically.
Equation for second order reaction rate law
r = k[A]^2
Equation for the relationship between reaction rates and reactant concentrations for the overall reaction
aA + bB + -> gG + hH + …
r = k[A]^m[B]^n
Equation for Overall order
order of overall equation = m + n
where m and n are the orders of reaction for A and B
What does a rate constant (k) do? And what does its value depend on?
The rate constant relates the rate of a reaction to reactant concentrations. Its value depends on the specific reaction, the presence of a catalyst (if any), the pressure of the system, and the temperature.
What happens to reactions with a larger value of k?
The reaction goes faster as k is bigger.
Does the value of k depend on the order of a reaction?
Does the value of k change as the reaction progresses?
Yes
No
Initial rates method
Initial rates method allows the values of these reaction orders to be found by running the reaction multiple times under controlled conditions and measuring the rate of the reaction in each case.
