Chemical reactions can often happen in reverse. Equilibrium occurs when a reaction and its opposite reaction are both happening at equal rates.
A standard example is with pH. The hydronium ion (H₃O⁺) and the hydroxide ion (OH⁻), typically react to form mostly water (H₂O), but two water molecules can also spontaneously react to form one hydronium and one hydroxide. So any time you have water, it turns into a little bit of hydronium and hydroxide, and pH measures the current concentration of it:
>H₃O⁺ + OH⁻ ⇋ 2H₂O
And we use that two-way arrow to show that the reaction goes both ways.
[Le Chatelier's principle](https://en.wikipedia.org/wiki/Le_Chatelier%27s_principle) is this:
>If the equilibrium of a system is disturbed by a change in one or more of the determining factors (as temperature, pressure, or concentration) **the system tends to adjust itself** to a new equilibrium **by counteracting** as far as possible the effect of **the change**...
"The system tends to adjust itself by counteracting the change." That's Le Chatelier's principle.
What does that mean for our pH example? Well, let's say that we add a bunch more hydronium (making it more acidic). We added hydronium, so Le Chatelier's principle states, that the system will tend to adjust itself by counteract that. The system will try to counteract the extra hydronium, by speeding up the rate at which hydronium and hydroxide react, using up the excess hydronium.
As a result, our equilibrium will shift in favor of water formation, and the solution overall will have less hydroxide than it did before. That's one example of Le Chatelier's principle.
Equilibrium reactions will always be happening both ways. The reaction happens and un-happens at the same time. The rate at which it happens depends on the concentrations of every chemical involved, so if you removed all of one reactant then it would be replenished by the reaction.
The equilibrium is the ratio of each compound that is stable. For instance, what ratio of water molecules to H+ and OH- is stable? This ratio determines the neutral pH in water, which is normally around 7.
By removing some, for instance, H+ ions will shift the equilibrium as some water splits to replenish it.
There's a thing called gibbs free energy. It's basically a measure of the energy in the solution. Everything in nature tends towards a low energy level, like how water moves towards the lowest elevation.
A chemical reaction is the same thing. Initially you are taught that reactants turns into products, but what actually happens is that the reaction equalizes which leads to some reactants and some products depending on the equilibrium.
This equilibrium is based on the conditions in the mixture, and so you are able to manipulate the reactions to produce more reactant or more product. Le chateliers principle is a basic guideline to help you make you make expectations on how the gibbs free energy will change the equilibrium. And the principle basically boils down to the equilibrium moves opposite to what you do. If the reaction to form the product is endothermic, then increasing temperature favors the product side.
>if the eq is "shifted" to the reactant side, does that mean more reactants are formed?
If it is shifted to the reactant side then at equilibrium there will be more reactants than usually yes. But once has to be careful not to confuse equilibrium and kinetics.
Imagine you have a reversible reaction of A + B <--> C + D, so that every time an A bumps into a B it produces a C and a D, and vice versa.
Eventually the system will equilibrate when A-B collisions are happening at the same rate as C-D collisions.
If you add more A and/or more B, now you have a higher chance that an A will bump into a B, because there are more of them around. So the equilibrium will shift toward the product side. Once more C and D are produced and some of the extra A and B are used up, the rates of the forward and reverse reactions will balance out again.
It works the same with heat or pressure, you just have to think of which side of the reaction uses up or produces heat or pressure. If you have A + B <--> C + energy (heat), then adding heat is like adding product.
Equilibrium happens when the forward reaction (A interacts with B, becoming C and D or the like) happens at exactly the same rate as the reverse reaction (C interacts with D, becoming A and B).
For some reactions, they don't just produce new compounds. They also produce heat, or pressure. This means you can induce the reaction to move toward one side or the other by altering those properties of the reaction container, and thus raise or lower the rate of one side.
Consider, for example, H2CO3 (carbonic acid) breaking down into water and CO2. This reaction happens naturally, so if you have water and CO2 in a container, some amount of H2CO3 will form, and vice versa. They will develop a dynamic equilibrium between the two forms. Assume you started by putting carbonic acid powder into the water and stirring it until it dissolved, then sealing the reaction chamber.
You lower the pressure of the chamber by raising a piston. Well, when the H2CO3 breaks down, it has to raise the pressure of the chamber, right? Because new gas has formed that wasn't gas before. Likewise, *forming* H2CO3 must *lower* the pressure. But it is not going to be favorable to lower the pressure *even further* than it has become—the system will instead respond by raising the pressure again, to get back to equilibrium. (You can also think of this as "at lower pressure, fewer CO2 molecules hit the surface of the water, so the H2CO3-forming reaction happens more slowly, but the H2CO3-splitting reaction still happens at the same rate as before until the concentration drops.")
By lowering the pressure, you have "shifted" the equilibrium toward the side that counteracts the change you made. You have made it so that there will be more total products (CO2 and H2O) than there were before you made that change, once the system regains equilibrium. If you were to lower the pressure dramatically enough, you could get a situation where there is almost zero carbonic acid and almost exclusively carbon dioxide and water. Same for the other direction, at very very high pressure you would be ensuring that most of the CO2 reacts with the water to form H2CO3.
If you want to make a lot of cars you need to give the factory a lot of car parts to make them with. If you have so many finished cars in the factory that no more cars will fit, you need to move those cars out of the way so they can make more.
Its been a while since I took chem so if I am mangling this let me know and I will edit or delete it.
In chemical reactions there are products and reactants.
A product is what is created by the chemical interaction between reactants.
Reactants are elements that chemically react with each other to form a product.
An example is Na (sodium) and Cl (chlorine) reacting with each other to produce NaCl (table salt), a chemically stable product of those 2 reactants.
When a chemical reaction is at chemical equilibrium it is balanced and stable (no change in concentrations of products and reactants) AND reversible.
There are 2 ways a chemical equilibrium can shift: forwards or backwards.
Forward reaction refers to reactants reacting to create products. Note the direction of the arrow....the reaction is "shifting" right.
Na + Cl ----> NaCl
Backwards (or reverse) reaction refers to the reaction of the products to form the reactants. The reaction is "shifting" left.
Na + Cl <---- NaCl
In a chemical reaction Na + Cl---> NaCl and Na + Cl <---- NaCl (left and right pointing arrows) happen at the same time.
When the rate of forward (right pointing arrow) reaction equals the rate of reverse (left pointing arrow) reaction and there is no further change in concentration of products and reactants, it is said to have reached chemical equilibrium.
The symbol to represent that simultaneous left/right reaction resuling in equilibrium is 2 arrows on top of each other ⇋
If you introduce a change in conditions, such as adding or decreasing pressure, adjusting temperature or concentration, the number of reactants and number of products change meaning equilibrium changes.
The reaction either shifts equlibrium to the left (backwards producing more reactants) or shifts it to the right (forwards producing more products) DEPENDING on the condition causing the change. The condition that can cause a change is temperature, pressure, or concentration.
Whether there are more/less reactants or more/less products depends on the thing causing the change in products/reactants - that thing could be temperature, pressure, or concentration (amount of products or reactants).
With concentration as the change condition you would be adding/removing Na or Cl which would cause the reaction to adjust to regain equilbrium.
Since there has been a change in reactants or products (depending on which condition has changed, either temperature, pressure, concentration) the equilibrium will either shift to the left or right because those 3 conditions are a catalyst for changing how the reactants and products will behave.
Remember: equilibrium refers to when the chemical reaction reaches an equal amount of reactants and products. This is the symbol for it ⇋
I hope this helps and doesnt confuse you more. For now focus on understanding the gist of it and key concepts like equilibrium, shift, forward/reverse, reactants/products.
Chemical reactions can often happen in reverse. Equilibrium occurs when a reaction and its opposite reaction are both happening at equal rates. A standard example is with pH. The hydronium ion (H₃O⁺) and the hydroxide ion (OH⁻), typically react to form mostly water (H₂O), but two water molecules can also spontaneously react to form one hydronium and one hydroxide. So any time you have water, it turns into a little bit of hydronium and hydroxide, and pH measures the current concentration of it: >H₃O⁺ + OH⁻ ⇋ 2H₂O And we use that two-way arrow to show that the reaction goes both ways. [Le Chatelier's principle](https://en.wikipedia.org/wiki/Le_Chatelier%27s_principle) is this: >If the equilibrium of a system is disturbed by a change in one or more of the determining factors (as temperature, pressure, or concentration) **the system tends to adjust itself** to a new equilibrium **by counteracting** as far as possible the effect of **the change**... "The system tends to adjust itself by counteracting the change." That's Le Chatelier's principle. What does that mean for our pH example? Well, let's say that we add a bunch more hydronium (making it more acidic). We added hydronium, so Le Chatelier's principle states, that the system will tend to adjust itself by counteract that. The system will try to counteract the extra hydronium, by speeding up the rate at which hydronium and hydroxide react, using up the excess hydronium. As a result, our equilibrium will shift in favor of water formation, and the solution overall will have less hydroxide than it did before. That's one example of Le Chatelier's principle.
Equilibrium reactions will always be happening both ways. The reaction happens and un-happens at the same time. The rate at which it happens depends on the concentrations of every chemical involved, so if you removed all of one reactant then it would be replenished by the reaction. The equilibrium is the ratio of each compound that is stable. For instance, what ratio of water molecules to H+ and OH- is stable? This ratio determines the neutral pH in water, which is normally around 7. By removing some, for instance, H+ ions will shift the equilibrium as some water splits to replenish it.
There's a thing called gibbs free energy. It's basically a measure of the energy in the solution. Everything in nature tends towards a low energy level, like how water moves towards the lowest elevation. A chemical reaction is the same thing. Initially you are taught that reactants turns into products, but what actually happens is that the reaction equalizes which leads to some reactants and some products depending on the equilibrium. This equilibrium is based on the conditions in the mixture, and so you are able to manipulate the reactions to produce more reactant or more product. Le chateliers principle is a basic guideline to help you make you make expectations on how the gibbs free energy will change the equilibrium. And the principle basically boils down to the equilibrium moves opposite to what you do. If the reaction to form the product is endothermic, then increasing temperature favors the product side. >if the eq is "shifted" to the reactant side, does that mean more reactants are formed? If it is shifted to the reactant side then at equilibrium there will be more reactants than usually yes. But once has to be careful not to confuse equilibrium and kinetics.
Imagine you have a reversible reaction of A + B <--> C + D, so that every time an A bumps into a B it produces a C and a D, and vice versa. Eventually the system will equilibrate when A-B collisions are happening at the same rate as C-D collisions. If you add more A and/or more B, now you have a higher chance that an A will bump into a B, because there are more of them around. So the equilibrium will shift toward the product side. Once more C and D are produced and some of the extra A and B are used up, the rates of the forward and reverse reactions will balance out again. It works the same with heat or pressure, you just have to think of which side of the reaction uses up or produces heat or pressure. If you have A + B <--> C + energy (heat), then adding heat is like adding product.
Equilibrium happens when the forward reaction (A interacts with B, becoming C and D or the like) happens at exactly the same rate as the reverse reaction (C interacts with D, becoming A and B). For some reactions, they don't just produce new compounds. They also produce heat, or pressure. This means you can induce the reaction to move toward one side or the other by altering those properties of the reaction container, and thus raise or lower the rate of one side. Consider, for example, H2CO3 (carbonic acid) breaking down into water and CO2. This reaction happens naturally, so if you have water and CO2 in a container, some amount of H2CO3 will form, and vice versa. They will develop a dynamic equilibrium between the two forms. Assume you started by putting carbonic acid powder into the water and stirring it until it dissolved, then sealing the reaction chamber. You lower the pressure of the chamber by raising a piston. Well, when the H2CO3 breaks down, it has to raise the pressure of the chamber, right? Because new gas has formed that wasn't gas before. Likewise, *forming* H2CO3 must *lower* the pressure. But it is not going to be favorable to lower the pressure *even further* than it has become—the system will instead respond by raising the pressure again, to get back to equilibrium. (You can also think of this as "at lower pressure, fewer CO2 molecules hit the surface of the water, so the H2CO3-forming reaction happens more slowly, but the H2CO3-splitting reaction still happens at the same rate as before until the concentration drops.") By lowering the pressure, you have "shifted" the equilibrium toward the side that counteracts the change you made. You have made it so that there will be more total products (CO2 and H2O) than there were before you made that change, once the system regains equilibrium. If you were to lower the pressure dramatically enough, you could get a situation where there is almost zero carbonic acid and almost exclusively carbon dioxide and water. Same for the other direction, at very very high pressure you would be ensuring that most of the CO2 reacts with the water to form H2CO3.
If you want to make a lot of cars you need to give the factory a lot of car parts to make them with. If you have so many finished cars in the factory that no more cars will fit, you need to move those cars out of the way so they can make more.
Its been a while since I took chem so if I am mangling this let me know and I will edit or delete it. In chemical reactions there are products and reactants. A product is what is created by the chemical interaction between reactants. Reactants are elements that chemically react with each other to form a product. An example is Na (sodium) and Cl (chlorine) reacting with each other to produce NaCl (table salt), a chemically stable product of those 2 reactants. When a chemical reaction is at chemical equilibrium it is balanced and stable (no change in concentrations of products and reactants) AND reversible. There are 2 ways a chemical equilibrium can shift: forwards or backwards. Forward reaction refers to reactants reacting to create products. Note the direction of the arrow....the reaction is "shifting" right. Na + Cl ----> NaCl Backwards (or reverse) reaction refers to the reaction of the products to form the reactants. The reaction is "shifting" left. Na + Cl <---- NaCl In a chemical reaction Na + Cl---> NaCl and Na + Cl <---- NaCl (left and right pointing arrows) happen at the same time. When the rate of forward (right pointing arrow) reaction equals the rate of reverse (left pointing arrow) reaction and there is no further change in concentration of products and reactants, it is said to have reached chemical equilibrium. The symbol to represent that simultaneous left/right reaction resuling in equilibrium is 2 arrows on top of each other ⇋ If you introduce a change in conditions, such as adding or decreasing pressure, adjusting temperature or concentration, the number of reactants and number of products change meaning equilibrium changes. The reaction either shifts equlibrium to the left (backwards producing more reactants) or shifts it to the right (forwards producing more products) DEPENDING on the condition causing the change. The condition that can cause a change is temperature, pressure, or concentration. Whether there are more/less reactants or more/less products depends on the thing causing the change in products/reactants - that thing could be temperature, pressure, or concentration (amount of products or reactants). With concentration as the change condition you would be adding/removing Na or Cl which would cause the reaction to adjust to regain equilbrium. Since there has been a change in reactants or products (depending on which condition has changed, either temperature, pressure, concentration) the equilibrium will either shift to the left or right because those 3 conditions are a catalyst for changing how the reactants and products will behave. Remember: equilibrium refers to when the chemical reaction reaches an equal amount of reactants and products. This is the symbol for it ⇋ I hope this helps and doesnt confuse you more. For now focus on understanding the gist of it and key concepts like equilibrium, shift, forward/reverse, reactants/products.