Unit 3.4.1 - Kinetics Flashcards
What is the rate of reaction?
The change in the amount of reactants or products per unit time
In a graph thats hows the amount of reactants or products against time what shows the rate of reactions?
The gradient
Does the rate of reaction increase with a larger or smaller surface area? And why?
Larger - there are more collisions so the reaction happens faster
What is the general rate equation for this equation: A + B → C + D ?
Rate = k[A]ᵐ[B]ⁿ
What does [A] mean?
The concentration of A
What does m stand for in: Rate = k[A]ᵐ[B]ⁿ?
The order of the reaction in respect to the concentration of A
What does the order of reaction with respect to a given reactant mean?
How that reactants concentration affects the rate of reaction
What is the overall order of a reaction?
The sum of all the powers in the rate equation
What does the k stand for in: Rate = k[A]ᵐ[B]ⁿ? And what does it mean?
The rate constant - the constant of proportionality in the rate equation
What does it mean if the order is 0?
The concentration of the reactants has no effect on the rate of reaction
What does it mean if the order is 1?
The rate of reaction is proportional to the concentration of the reactants
If the concentration of a reactant triples how does that affect the rate of reaction is the order to that reactant is 1?
The rate of reaction is three times faster
What does it mean if the order is 2?
The rate of reaction is proportional to the concentration of the reactants squared
If the concentration of a reactant triples how does that affect the rate of reaction is the order to that reactant is 0?
The rate of reaction remains the same
If the concentration of a reactant triples how does that affect the rate of reaction is the order to that reactant is 3?
The rate of reaction is 3² = 9 times faster
Does the rate of reaction increase when k increases or decreases?
Increases
What affects k? And how?
Temperature - as temperature increases so does k
Does k change when concentration and pressure changes?
No
What is the initial rate of reaction?
The rate right at the start of the reaction
What can you find out by doing the initial rate method?
The order of the reaction in respect to different reactants
Describe the initial rate method in 4 steps.
- ) do an experiment measuring the amount of reactant or product over time
- ) repeat with different concentrations of the the reactants
- ) calculate the initial rates from the graphs of each experiment
- ) then you can see how the concentrations affect the initial rate and so you can find the orders of the reaction
If a reaction has a series of steps what is the rate of reaction determined by?
The step with the slowest rate of reaction
The step with the slowest rate of reaction in a reaction that involves a series of steps is called?
The rate determining step
How can you use the rate equation to help find out which is the rate determining step?
If a reactant appears in the rate equation, then it or something derived from it must be in the rate determining step, if its not in the rate equation then it won’t be in the rate determining step
How do you know something is a catalyst from the rate equation?
It appears in the rate equation but not in the overall equation
What else does the rate equation show in relation to the rate determining step?
The number of molecules of each reactant in the rate determine step, if its second order then there will be two molecules
What does a graph of k against temperature look like?
What do the graphs look like for concentraion aginst rate of reaction for 0, 1st, 2nd look like?
