Реферат: Rate Of Reaction In Sodium Thiosulphate And
is called the activation energy, or Ea. The size of this activation energy is
different for different reactions. If the frequency of collisions is increased
the rate of reaction will increase. However the percent of successful
collisions remains the same. An increase in the frequency of collisions can be
achieved by increasing the concentration, pressure, or surface area.
Concentration ? If the concentration of a solution is increased there are more
reactant particles per unit volume. This increases the probability of reactant
particles colliding with each other.
Pressure – If the pressure is increased the particles in the gas are pushed
closer. This increases the concentration and thus the rate of reaction.
Surface Area ? If a solid is powdered then there is a greater surface area
available for a reaction, compared to the same mass of unpowdered solid. Only
particles on the surface of the solid will be able to undergo collisions with
the particles in a solution or gas.The particles in a gas undergo random
collisions in which energy is transferred between the colliding particles. As a
result there will be particles with differing energies. Maxwell-Boltzmann
energy distribution curves show the distribution of the energies of the
particles in a gas.
The main points to note about the curves are:
1. There are no particles with zero energy.
2. The curve does not touch the x-axis at the higher end, because there will
always be some particles with very high energies.
3. The area under the curve is equal to the total number of particles in the
system.
4. The peak of the curve indicates the most probable energy.
The activation energy for a given reaction can be marked on the distribution
curve. Only particles with energy equal or greater than the activation energy
can react when a collision occurs.
Although Maxwell-Boltzmann distribution curves are for the particles in a gas,