Rates Of Reaction Flashcards
How does a zero order rate conc graph look?
Linear and horizontal, the rate does not change with concentration
How does a first order rate conc graph look?
The rate is proportional to the conc, so it is a positive correlation graph.
How does a second order rate conc graph?
Curve
How do we determine the initial rate? What is the gradient of a conc time graph?
Draw a tangent at t=0 on a conc time graph at the start of the reaction. Steepest gradient and fastest rate
Rate
What is the overall order rate of reaction?
Sum of the individual orders all the conc terms are raised to
How do we identify a first order reaction from a conc time graph? How do we know it is NOT first order?
The half life is constant and the same.
The half life is NOT constant.
How does a zero order conc time graph look?
Conc decreases at a constant rate
Half life decreases with time
Negative correlation
How does a first order conc time graph look?
Conc halves in equal time intervals
Half life is constant
Downwards curve
How does a second order conc time graph look?
Conc decreases rapidly, then the rate of decrease slows down
Half life increases with time
Deep curve
Describe what happens to the concentration as the reaction proceeds
As the reaction proceeds, the conc of the reactants decrease. They get used up because there are fewer collisions per second. The rate therefore slows down and the gradient gets less steep.
Explain the correlation between the tangent and slope
At any instant of time, the rate is equal to the slope of the curve
Explain how you can collect data for conc time graphs through continuous monitoring
You can continuously monitor by :
1) monitoring by gas collection ( measuring the gas volume with a gas syringe at regular time intervals )
2) mass loss
How do we monitor the rate with a colorimeter?
We measure the absorbance of a solution by looking at the wavelength of light passing through a coloured solution. This is controlled by using a filter.
What is the formula to calculate the rate of reaction and it’s units? What does it measure?
Rate = change in conc / time
Units = mol dm -3 s -1
How quickly reactants used up or products formed
What is the rate determining step?
The slowest step
Governs the overall ROR
