Kinetics Flashcards
(35 cards)
What is rate of reaction and the units?
-rate of reaction is the change in concentration of a reactant or product in a given period of time.
-units are mol dm^-3s^-1
what factors affect the rate of a chemical reaction?
temperature
concentration
catalyst
What do the rate of reaction is dependent on?
frequency of successful collisions
Whats the effect of temperature on reaction rate?
-increasing the temperature increases the rate of reaction
-at higher temperatures the particles have more energy and move faster, leading to more frequent and successful collisions between particles in a given time
what happens to the Maxwell-Boltzmann distribution when the temperature increases?
-The curve is moved to the right and the peak is lower
-the graphs should only touch once
-The curves should always start at the origin
What is the effect of concentration on reaction rate?
-increasing the concentration of a reactant increases the rate of reaction
-there are more reactant particles which leads to more successful collisions in a given time
-for gases: we can increase the rate of reaction by increasing the partial pressure of the reactants (as this increases the concentration)
what happens to the Maxwell-Boltzmann distribution when the concentration increases?
-The curve retains the same basic shape but higher than the lower concentration
-The most probable energy of the molecules remains the same
-The overall area under the curve increases
What is the effect of a catalyst on reaction rate?
-Increases the rate of reaction by providing an alternative route for the reaction with a lower activation energy
-chemically unchanged at the end of a reaction
what happens to the Maxwell-Boltzmann distribution when added catalyst?
-The shape does not change
-The activation energy has a lower value (increase in the number of molecules with sufficient energy to collide successfully
What methods can be used to determine reaction rates?
-Measuring gas production
-Colorimetry
-Titration
-pH monitoring
what is the rate formula
Rate= k[A]^a [B]^b [C]^c
what is zero order reaction?
the rate of reaction is independent of the concentration of X (Rate is constant)
Rate= k[X]^0 = k
what is first order reaction?
the rate is directly proportional to the conc of X
Rate= K[X]^1 = K[X]
what is second order reaction?
rate is proportional to the square of the conc of X.
Rate= K[X]^2
what is overall reaction order?
sum of the orders of all components
whats k
rate constant
rearrange the rate equation to make the k the subject
k= rate/ [B]^b [C]^c
what is the gradient of line in a rate vs conc graph ?
k, rate constant
How to determine the order of graph
calculate the half life
what is half life
-time taken for the conc of a reactant to fall to half its initial value
what line shows the zero order on a graph rate vs conc?
straight horizontal line coming from the y axis
what line shows the first order on a graph rate vs conc?
diagonel line with a constant gradient coming from 0
what line shows the second order on a graph rate vs conc?
a curve
what line shows the zero order on a graph conc vs time?
a straight line
