How Fast? Flashcards
What is the rate of a chemical reaction?
The Chang of concentration of reactant or product per unit time
Changing the concentration of substances taking part in a reaction usually* changes the rate of reaction
- not always
What happens if the order of a reactant is 0?
Rate doesn’t change
What happens if the order of a reactant is 1?
The affect is directly proportianal
Is [B] = x2 then rate= x2
What happens if the order of a reactant is 2?
The effect would be indirectly proportional to
Squared relationship
[C]= x2
Rate= x4
What are methods of continuous monitoring?
1 - collecting the gas produced during a reaction
2 - mass lost using a reaction
3 - colour change using a colorimeter
How is rate of reaction calculated?
Rate = change in concentration
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Time
The gradient of the line gives the rate of the action at that time
What changes the shape of a concentration-time graph?
The order of reaction with respect to a particular reactant
First and second order are too similar for a strong conclusion
What is the half life of a reaction?
Time taken for the concentration of a reactant to fall to half the original value
THE HALF LIFE OF A FIRST ORDER REATION IS CONSTANT: it is independent of the concentration of the [reactant]
Within 10% can be regarded as constant
How is rate constant calculated?
k = ln2 / t of half life
How is rate-concentration graph data generated?
- draw a concentration-time graph an calculate the gradient (rate) at different concentrations so rate can be plotted against concentrations, tangents can be used to prove that a reaction is first order
- record the overall tie taken for a reaction to complete at different concentrations, so 1/t can represent rate
Why do we have mechanisms?
Collisions between more than two species simultaneously are unlikely
