What Factors Affect the Speed of Oxidation/Reduction Reactions?

In summary: The speed of the molecules does not change, however, the probability of favorable collisions does increase as the surfaces of the reactants become larger.
  • #1
WavesOfPhysics
6
0
In Ox/Red reactions there 3 factors that can speed up a reaction between 2 compounds:

the first being a greater concentration, which is pretty easy to comprehend.

What I don't understand is how heat affects the speed of a reaction ( at a micro level)
and how is adding a third component to the reaction sometimes makes it faster.
 
Chemistry news on Phys.org
  • #2
It's related to collision theory, and the Maxwell-Boltzmann distribution.
This is shown mathematically in the Arrhenius equation

[tex]k=Aexp(-E_a/RT)[/tex]
where k is rate constant
A: the collision factor (say A = 50000)
What happens if you increase the temperature from 293 K to 303 K?

i.e.
[tex]k(303) / k(293) \approx 2,0[/tex]
You can see that the fraction of the molecules able to react has almost doubled by increasing the temperature by 10°C.
 
  • #3
WavesOfPhysics said:
In Ox/Red reactions there 3 factors that can speed up a reaction between 2 compounds:

the first being a greater concentration, which is pretty easy to comprehend.

What I don't understand is how heat affects the speed of a reaction ( at a micro level)
and how is adding a third component to the reaction sometimes makes it faster.

There are many more factors involved in rates of reaction other than simply concentration and temperature.

As above you can look at the Arrhenius equation to get some quantitative information. If you are interested in understanding what is happening (not the Maths) then you can check out "activation energy." You will undoubtedly see the Arrhenius equation on your travels through "activation energy land."

You need to be more specific about what you mean by "adding a third component." Are you referring to something like a catalyst? Catalysis is a huge field but it works by modifying the activation energy needed to overcome an energy barrier. Once again, google is your friend here.
 
  • #4
A third factor are:

the speed of molecules also increasing with larger surface of the reactants
 
Last edited:
  • #5
janhaa said:
A third factor are:

the speed of molecules also increasing with larger surface to the reactants

Please elaborate, what you wrote doesn't make much sense to me.
 
  • #6
Borek said:
Please elaborate, what you wrote doesn't make much sense to me.
Say we have CaCO3 into (large) pieces which react with 2 M HCl, versus crushed CaCO3 with the same HCl.
Latter reaction will most fizz, because the probability of favorable collisions increases with increasing surfaces

(hope you understand)
 
  • #7
thanks for these replies, most of my questions were very well answered but one which was complety forgotten, how does energy affects molecules ( that's what I meant by micro level )
 
  • #8
janhaa said:
Say we have CaCO3 into (large) pieces which react with 2 M HCl, versus crushed CaCO3 with the same HCl.
Latter reaction will most fizz, because the probability of favorable collisions increases with increasing surfaces

Contrary to what you wrote earlier, it is not the speed of the molecules that changes the outcome in this case.
 

1. What are the factors that affect the speed of chemical reactions?

The factors that affect the speed of chemical reactions include temperature, concentration, surface area, presence of a catalyst, and nature of reactants.

2. How does temperature affect the speed of chemical reactions?

Increasing the temperature of a reaction generally increases the speed of the reaction. This is because higher temperatures provide more kinetic energy to the reactant molecules, allowing them to collide more frequently and with greater energy, leading to a faster reaction rate.

3. What is the relationship between concentration and reaction rate?

The higher the concentration of reactants, the faster the reaction rate. This is because higher concentrations mean there are more particles present, increasing the chances of successful collisions between reactant molecules.

4. How does surface area affect the speed of reactions?

A larger surface area of a reactant leads to a faster reaction rate. This is because a larger surface area means more exposed particles, which can react with other molecules. This is why reactions between solids typically occur faster when the solid is ground into smaller particles.

5. Do all reactions require a catalyst to occur?

No, not all reactions require a catalyst. However, a catalyst can significantly increase the rate of a reaction by providing an alternate pathway for the reaction to occur with lower activation energy. This allows the reaction to occur more quickly and efficiently.

Similar threads

Replies
7
Views
4K
Replies
5
Views
3K
Replies
2
Views
2K
Replies
4
Views
1K
  • Chemistry
Replies
4
Views
2K
  • Materials and Chemical Engineering
Replies
2
Views
2K
  • Biology and Chemistry Homework Help
Replies
2
Views
8K
  • Chemistry
Replies
2
Views
7K
  • Sci-Fi Writing and World Building
Replies
22
Views
3K
Replies
2
Views
3K
Back
Top