Why do smaller particles have large surface area and euilibrium

[scilearner]

Hello guys,

 

This might be a simple concept for you guys but I'm bit confused. We are learning rates of reaction and why does a crushed tablet react quicker than a full tablet. Any diagrams to help me with this would also be great.

 

And while we are at I got few questions on equilibirum constant.

 

Let's say we have to write our own equation and let's say its a combustion reaction. We can choose if the product water is liquid or gas. But If choose liquid I won't be able to use it in the equillibirum constant Kp. So which state do I use

 

Why is temperature the only thing that changes th equilibirum constant?

 

Any help in any of these questions would be greatly appreciated.:-)Thank you!!

[Mr Skeptic]

Hello guys,

 

This might be a simple concept for you guys but I'm bit confused. We are learning rates of reaction and why does a crushed tablet react quicker than a full tablet. Any diagrams to help me with this would also be great.

 

The crushed tablet has more surface area.

 

And while we are at I got few questions on equilibirum constant.

 

Let's say we have to write our own equation and let's say its a combustion reaction. We can choose if the product water is liquid or gas. But If choose liquid I won't be able to use it in the equillibirum constant Kp. So which state do I use

 

You could choose the more useful one. You can convert water between liquid and gas as a separate reaction.

 

Why is temperature the only thing that changes th equilibirum constant?

 

I doubt that.

[CaptainPanic]

The reaction rate is generally expressed as something that looks like this:

 

[math] Rate = K*e^{-\frac{E_a}{RT}} * [substance A]^a * [substance B]^b [/math]

 

 

The factors that are of importance are

-[math][substance A][/math], Concentration or pressure (which are the same in fact)

-[math]T[/math], Temperature

-[math]E_a[/math], Activation energy - this is a substance specific energy that says how easy something reacts

 

Other factors are more macroscopic (not molecule scale, but bigger scale), but if you have a perfectly mixed solution, these should have no influence at all. These other factors are the heat and mass transfer, and will become important if you are dealing with heterogeneous systems and catalysis, like the reacting tablet.

 

If something in the tablet should react with the liquid, then the liquid and tablet must be in contact with each other. If you crush the tablet, the liquid can reach the inside of the tablet much faster... Or, in other words: after crushing the tablet, there is much more outside surface of the tablet than before.