Rate Equations Flashcards
What is the rate of resction?
The change in concentration of a substance in a given time
What is rate of reaction measured in?
Moldm-3 s-1
What is activation energy?
The minimum energy required to start a reaction by the breaking of bonds
In rate equations, what do the powers of the reactions indicate?
The order of the reaction with respect to that reactant
What is the overall order of a reaction?
The sum of the orders of each reactant
How do you calculate the units of the rate constant K
Units of rate/ units of overall order
What is a rate concentration graph?
Shows how the rate of a reaction is affected by the concentration of a reactant, depending on its order
How does a zero order affect a rate concentration graph?
The change in conc. doesnt affecet rate. Rate remeians the same throughout
How does a first order affect a rate concentration graph?
The graph shows a linear line going through the origin. The change in rate is proportional to the change in concentration.
How does a second order affect a rate concentration graph?
The change in rate is proportional to the change in concentration squared
Line goes through the origin.
What is a concentration time graph?
Shows how the concentration of a reaction changes during the reaction.
What is a concentration time graph?
Shows how the concentration of a reaction changes during the reaction.
How can a conc. time graph be used to calculate the rate of reaction
Gradient= rate
How does a zero order affect a concentration time graph?
The gradient doesnt change, so the rate is constant
How does a first order affect a concentration time graph?
As conc, decreases the rate decreases as the gradient becomes less shallow
How does a second order affect a concentration time graph?
The gradient becomes shallower more quickly, rate decreases by squared what the conc. decreases by
What is the rate determining step?
The slowest steo in a rate reaction
How can you identify a rate determining step?
The step must have the same stoichiometry as the overall equation
Step must contain the same reactants as the overall eauation
How does temoerature effect the rate of reaction?
As temperature increases, the rate of reaction increases because there are many more particles with energy greater than the activation energy. So there are more successful collisions
How does a change in temperature affect K (rate constant)
If temperature increases, but the conc. of reactants remains the same K will increase with temperature exponentially.
What equation is used to show the rekationship between temperature and the rate constant K?
Arrhenius equation
In the arrhenius equation, what are the units of temperature and activation energy?
Temperature is Kelvin
Activation energy is Jmol-1
Using a graph, how can you use the arrhenius equation to calculate activation energy?
Plot a graph with lnK on the y axis and 1/T on the x axis.
Plot the points and draw line of best fit
Using the equation, the gradient = -Ea/ R
Calc the gradient of lone of best fot and rearange to fond Ea
