[BlackSnowMarine]

I just don't understand the concept of Equilibriums. I asked my teacher so many times and I feel like I irritate the crap out of her. I keep getting different definitions for an equilibrium. I've read that it's the same proportion of reactants and products, I've read that it's the same ratio of reactants and products, I've read that it's the same amount of reactants and products, I've read that it's the same concentration of reactants and products, and I've read that it's the same rate of forward and reverse reactions.

Sometimes, scientists are just so inconsiderate where they don't even use the same definition. It ticks me off. I don't know the differences between these definitions, let alone the differences between proportions, ratios, amounts, concentrations, and rates. My chemistry class already understands the concept from Day 1, while I'm just there wondering how my life will screw me up because I don't understand this. I come in before/after class, but none of it helps because I feel like I irritate the teacher, so I tend to sit there idle. I'm definitely going to fail the test, and fail to achieve my overall dreams of going in the science field.

[AWK]

Scientists always use very precise definitions. That unexperienced readers assign different meanings to precise terms.
Ratio and proportion have the same meaning as mathematical division.
Chemists always use concetrations (for more advanced problems  - activities (=effective concentrations)) in the equlibrium calculations. But in some cases amounts in moles may be used instead of concentrations (this exception should be omitted at the preliminary level of study).
Equilibrium is accomplished when both forward and reverse reactions show the same rate.

[BlackSnowMarine]

That's the thing. I don't know why equilibrium occurs. I don't understand how forward and reverse reactions balance to obtain the same rate. I don't know why and how it does that. Does equilibrium occur because gravity? Does it occur just because it occurs naturally?

[Borek]

I keep getting different definitions for an equilibrium.

Hard to comment not seeing the context of each thing you listed. First of all, I would not call them definitions (perhaps with the exclusion of the last one), they are just describing behavior of the system at equilibrium.

If the system is at equilibrium, it doesn't change in time, or the changes are not changing the system state.

I've read that it's the same proportion of reactants and products

If the system doesn't change, proportion stays constant. Doesn't mean if the proportion stays constant, system is at equilibrium.

I've read that it's the same ratio of reactants and products

How is it different from the previous statement? Are ratio and proportion two different things? Can one change and the other stay constant?

I've read that it's the same amount of reactants and products

If the system doesn't change, amounts stay constant.

I've read that it's the same concentration of reactants and products

If the system doesn't change, concentrations stay constant.

and I've read that it's the same rate of forward and reverse reactions.

This one is slightly different - it describes how the system stays unchanged. As the forward and backward reaction proceed at the same speed, neither amount nor concentration of the substances present change. How much is consumed is also produced, and the net effect is zero.

I don't know the differences (...) between proportions, ratios, amounts, concentrations, and rates.

If you don't know what these thing mean, you have no chance of understanding why all the statements you have listed can describe the same situation. However, don't blame scientists for that - you can't understand the definition when it uses notions that you don't understand. If I will tell you an abelian group is - by definition - a commutative group, you would have still no idea what I am talking about - but it is hardly my fault.

You have to start at the very beginning - proportions and ratios are not chemistry, more like a basic algebra. Amount, concentration and reaction rate are definitely chemistry, but I bet they were introduced to the class earlier.

[BlackSnowMarine]

So equilibriums having the same proportions, amounts, and concentrations are just describing the behavior? And equilibriums having the same rate of forward and reverse reactions is the actual definition?

But I'm still confused to why equilibriums occur? Why and how do the forward and reverse reactions balance out? Do they balance because of gravity? Because of external forces? Because of natural reasons? Because they just balance out and nobody knows why but scientists just went along with it? (I think like a philosopher, which makes me feel absolutely stupid, so I apologize).

[Borek]

So equilibriums having the same proportions, amounts, and concentrations are just describing the behavior? And equilibriums having the same rate of forward and reverse reactions is the actual definition?

Definition says something like "system is at equilibrium when all forces/influences cancel out and system stays unchanged".

But I'm still confused to why equilibriums occur?

When the forces/influences cancel out there is no NET force/influence that could change the system.

Why and how do the forward and reverse reactions balance out? Do they balance because of gravity? Because of external forces? Because of natural reasons? Because they just balance out and nobody knows why but scientists just went along with it? (I think like a philosopher, which makes me feel absolutely stupid, so I apologize).

Most of what you wrote is completely irrelevant.

Imagine you have a mixture of reacting substances. Rate of their reaction depends on their concentrations, roughly speaking, the higher the concentrations, the faster the reaction. Now, once they react we have products. These products can react back to produce the original reactants. Again, rate of their reactions depends on their concentrations, again, roughly speaking, the higher the concentrations, the faster the reaction. If there are no products, forward reaction is the fastest, and backward reaction has rate of zero. When there are products only, backward reaction has the maximum rate, and the forward reaction rate is zero. For some point in between these rates must be identical - once you get there, system is at equilibrium, as exactly the same amount of reactants/products is created/consumed in any given time.

[BlackSnowMarine]

"Rate of their reaction depends on their concentrations, roughly speaking, the higher the concentrations, the faster the reaction."

Sweet! That was all I needed basically, but thanks!

But then this leads to my question to why the concentrations speed up/slow down the reactions. But I'd rather not ask.

[Borek]

But then this leads to my question to why the concentrations speed up/slow down the reactions. But I'd rather not ask.

Kinetic theory of chemical reactions says that two molecules must collide for the reaction to take place. The higher the concentration, the more the molecules, the more collisions, the faster the reaction.

[Durlag]

Hi BlackSnowMarine. I don't know if it's ok to post links to other sites here, but here are a few links that could help you understand better (it helped me) and give you answers to your questions.

http://www.chemguide.co.uk/physical/kt/basic.html#top (this is about kinetic theory, I found it really well explained and it could answer some of your questions as to "why")
http://www.chemteam.info/Equilibrium/Equilibrium.html (the "equilibrium tutorials and problems" part)
http://www.chemguide.co.uk/physical/equilibria/introduction.html#top (another link about equilibria, haven't read it though)

Good luck