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Sunday, January 30, 2011

collision theory continue...

We know that the particles of matter (solid, liquid, gas) are moving all the time. Solid just vibrate in fixed position, liquid move randomly-fast and gas move freely - faster.

Do you think that moving particles are collide each other?

See this video.




So what do you think. How is this movement and collision related to chemical reaction?

In chemical reaction, the substance reacted (reactant) and formed the new product. Let's consider from the equation below:


The particles of Zn (Zinc atom) and the particles of HCl (Hydrogen ion) must collide before they can react to form new substances which is ZnCl2 and H2.

Collisions must satisfy TWO CONDITIONS before they can result in reaction to form the product :

1. The colliding reactant particles must have enough energy.
2. The reactant particles must be oriented correctly when they collide.

Collisions that result in reaction between particles and formed the product called effective collision.


Why reactant particles MUST HAVE ENOUGH ENERGY ?

Lets look an analogy the man push up the big rock over the small hill.

The man must have a strong force to push the rock to overcome the small hill





We can consider the small hill is barrier must be overcome, to push up the big rock over the barrier, the man must have more energy to push the rock.

In chemical reaction, barrier like as Activation Energy, Ea. Particles of reactant must have enough energy to overcome the Activation Energy, Ea. See an example video here.





What we can said ;

When Marble A have low energy, Marble A can't push Marble B and move down the slope together. (Marble A not enough energy - move slower - low kinetic energy) - insufficient energy

When Marble A have medium energy, Marble A can push Marble B(bounce) not move down the slope together.
(Marble A not enough energy - just rebound ) - insufficient energy

When Marble A have high energy, Marble A can push Marble B and move down the slope together.
(Marble A have enough energy - form new product) - sufficient energy

Energy content of reacting particles must be equal or higher than the Activation Energy of reaction.

ENERGY CONTENT of reacting particles, Ec  ≥ ACTIVATION ENERGY of reaction , Ea

WHAT IS ACTIVATION ENERGY?

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