1.9 Reaction rates Flashcards
1
Q
what is meant by reaction rate?
A
- change in amount of reactant or product per unit time
2
Q
how can we obtain the rate of reaction from an amount of product or reactant - time graph?
A
- take the gradient of the graph
- remember to include units
3
Q
what happens if the graph contains a curve?
A
- make a tangent at time t
- take gradient
- include units
4
Q
what does a rate equation actually tell us?
A
- how the rate of reaction is related to the concentrations of reactants
5
Q
what are the units of rate?
A
moldm^-3s^-1
6
Q
Rate = k [A]^m [B]^n
what can you tell me about this ?
A
k = rate constant
[A] and [B] are concentrations of reactants
m and n are orders
7
Q
what is an order of a reaction?
A
- power to which the concentration is raised to in the rate equation
- tells you how the concentration of a reactant affects the rate
8
Q
the bigger the value of k…
A
the faster the rate of reaction
9
Q
how can you determine order from concentration time graphs?
A
- find gradient at various points on graph
- plot each point on rate concentration graph
- shape determines order
10
Q
what is the RDS?
A
- slowest step in a multi step reaction
- determines the overall rate of reaction
11
Q
what is the Arrhenius equation?
A
k = Ae*-Ea/RT
12
Q
how can we rearrange this equation?
A
take logs natural logarithm
ln k = -Ea/RT + lnA
13
Q
A
