What is a reaction rate?
Key Terms
State the formula for a rate of reaction
Rate of reaction = Change in concentration / Time taken
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| Term | Definition |
|---|---|
What is a reaction rate? | Change in concentration (or amount) of reactant or product over time |
State the formula for a rate of reaction | Rate of reaction = Change in concentration / Time taken |
Name the 2 conditions needed for particles to react with one another when they collide | Collide in right direction
Need to be facing each other in right way
Collide with certain minimum amount of kinetic energy |
What is meant by activation energy? | Minimum (amount of kinetic) energy needed for a reaction to occur |
Why do particles need a minimum amount of kinetic energy for them to react? | Need to have this much energy to break their bonds & start reaction |
Molecules in gas don’t all have the… | same amount of energy |
What does a Maxwell-Boltzmann distribution show? | Number of molecules in a gas with different kinetic energies |
Draw a Maxwell–Boltzmann distribution | (y axis) %/fraction of particles/molecules/atoms (x axis) energy |
Maxwell–Boltzmann Distribution What does the peak of the curve represent? | |
Maxwell –Boltzmann Distribution Where is the mean (average) energy of all molecules on the curve? Label it on your curve. | |
Maxwell–Boltzmann Distribution At what speed are most molecules moving at? | |
Maxwell–Boltzmann Distribution Shade the area where there’s molecules that can react | |
What is the area under a Maxwell–Boltzmann distribution curve equal to? | Total number of molecules |
Why does the Maxwell–Boltzmann distribution curve start at (0,0)? | Because no molecules have 0 energy |
Describe the effect of temperature on reaction rate |
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Describe and illustrate the effect of an increase in temperature on Maxwell–Boltzmann distribution curve | Changes shape of Maxwell–Boltzmann distribution curve → shifts to the right |
Why does a small increase in temperature create a large increase in reaction rate? (2) | Many more molcules have E ≥ Ea (energy greater than the activation energy)
Far more successful collisions per second |
Describe the effect of concentration on reaction rates |
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Describe the effect of pressure on reaction rates | Gas particles closer together
↑ collsion frequencies = reaction rate ↑ |
What is a catalyst? |
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Catalysts take part in reactions but… | are remade at end |
Draw a Maxwell–Boltzmann distribution showing the effect of a catalyst work | |
Describe how you can measure reaction rates | Measure how fast reactants are used up or how fast products are formed |
Name 3 ways to measure reaction rates |
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Measuring reaction rates Describe "measuring a decrease in mass" |
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Measuring reaction rates Describe "measuring the volume of gas given off" |
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