Chemical Industry 4: Order & Rate Equations Flashcards
Definition of order of a reaction
How much the concentration of a reactant effects the rate
How is order shown in the rate equation
Power to which the concentration of the reactant is raised in the rate equation
What are 3 orders
- 0 order
- 1st order
- 2nd order
Explain the effect of 0 order
- rate is proportional to [ A ]^0 = 1
- Rate is not affected by changes in [ A ] = rate remains the same
What do [ ] stand for
Concentration of in moldm^-3
Explain the effect of 1st order
- Rate is proportional to [ A ] or [A]^1
- whatever you do to [A ] you do the same to rate
Eg. [ A ] x2 = rate x2
Explain the effect of 2nd order
- Rate is proportional to [A]^2
- whatever you do to [A ] you square it and apply to rate
Eg. [ A ] x2 = rate x2^2 = rate x4
What are the units of rate
Moldm^-3 s^-1
concentration / time
Write expression of reaction rate equation for xA + yB —> products
Reaction rate = k [A]^m [ B ]^n
( k = (proportionality) rate constant & m/n = order number )
Note m/n are nothing to do with x/y
How can orders of reaction be found
Can only be found experimentally can not be found by looking at original chemical equation
What is the rule for catalysts and rate equations
Although catalyst not in chemical equation can still appear in rate equation
What is k
Rate constant for a reaction = different for different reactions
What is the only thing that effects k
Temperature
- k increase with temperature
( usually in experimental data given temperature would have remained constant )
How do you work out the units of k
- Rearrange rate equation
- use order of reactions of different concentrations
LOOK IN NOTES
What is the overall order of reaction
Sum of powers of the concentration terms in the rate equation
Be able to deduce rate equation from table of experimental data
Look at notes
What does a rate ( Y ) against concentration ( X) graph look like for 0 order
Horizontal line, —
What does a rate ( Y ) against concentration ( X) graph look like for 1st order
Rising straight line, /
What does a rate ( Y ) against concentration ( X) graph look like for 2nd order
Upwards curve
What 2 methods can used to produce experimental data for rate-concentration graphs
- INITIAL RATES METHOD = Doing several experiments where initial rate is measured & initial concentration of reagent is changed
- CONTINUOUS RATES METHOD = doing 1 experiment where the rate and concentration of a reagent is measured at several times during that one reaction
How can an iodine clock reaction be monitored
Progress of reaction can be measured by following the colour of iodine produced using starch = colourless —> blue-black complex
