The Maxwell Boltzmann Distribution | A-level Chemistry | OCR, AQA, Edexcel

Описание: The Maxwell Boltzmann Distribution in a Snap!

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The key points covered in this video include:
1. What is the Maxwell Boltzmann Curve?
2. Maxwell-Boltzmann Curve
a) Temperature
b) Catalysts

What is the Boltzmann Curve?

The Boltzmann Curve shows the distribution of molecular energies in a gas at a constant temperature. Some molecules: Move fast and have a high energy, Move slow and have a low energy. The majority of molecules have an average energy. Features of the Curve: The area under the curve is equal to the total number of molecules in the sample, The curve starts at the origin, There are no molecules in the system with zero energy. Only molecules with an energy greater than the activation energy, Ea, can react.

Boltzmann Curve: Temperature

At higher temperatures, the kinetic energy of the molecules increases. The peak moves: Moves to the right, Lower peak. The area under the curves remains the same. The number of molecules in the system remains the same. What happens? The molecules are moving faster as they have more kinetic energy, A greater proportion of molecules have an energy that is greater than the activation energy, More successful collisions occur in a given length of time, The Rate of Reaction will increase.

Boltzmann Curve: Catalyst

Catalysts lower the activation energy of a reaction. They do this by: Providing an alternative reaction route, This route requires a lower activation energy. The addition of a catalyst does not change the distribution of the molecular energies. What Happens? More molecules in the system have an energy in excess of the new, lower activation energy, More successful collisions occur in a given length of time, The rate of reaction increases.

Summary

The Boltzmann-Distribution is the distribution of energies of molecules at a particular temperature
a. Often shown as a graph
Important features of the graph:
a. Never touches the x-axis
i. No molecules have 0 energy
b. No maximum energy for the molecules
c. The area under the curve is equal to the total number of molecules
d. Only molecules with energy greater than activation energy can react
When the temperature is increased:
a. The curve moves down and to the right
b. The area under the curve remains the same
A Catalyst lowers the activation energy
a. More molecules have an energy in excess of the new, lower activation energy