Need help with chemistry!

So chemistry sucks, and I have to have it for 2 years.

The problem is that there's so much in chemistry that just doesn't make any sense to me and I have problems remembering how to calculate the different things because every calculation to figure out shit is the longest calculation you have ever seen!

Anyways, I really want to get a better grade than I have now(I have a 2 in chemistry and I want at least a 4) and I need get my shit together quick. So does anyone how any suggestions on how to get better? like any programs or something I could go through or anything? I'm really desperate :(

Thanks

Cyfu:
So chemistry sucks, and I have to have it for 2 years.

*gasp* You should be ashamed!

The problem is that there's so much in chemistry that just doesn't make any sense to me and I have problems remembering how to calculate the different things because every calculation to figure out shit is the longest calculation you have ever seen!

Anyways, I really want to get a better grade than I have now(I have a 2 in chemistry and I want at least a 4) and I need get my shit together quick. So does anyone how any suggestions on how to get better? like any programs or something I could go through or anything? I'm really desperate :(

Thanks

Right, question time...

1) What level of chemistry? (e.g. NMR: spectral prediction; low-res interpretation; high-res interpretation; NOESY... TOCSY?!)
2) What type of chemistry? (physical/inorganic/organic/analytical)
3) How good are you at maths/physics/biology?
4) How're you being taught at the moment?
5) What materials are your institution giving you?

I think that's all for now... but generally speaking, other than rote memorisation and doing questions, not much you can do to get around it. Chemistry as a university subject is just too expansive to really say that 'here's a book that contains it all' or 'here's a program that'll teach it all' etc.

If you say which form of chemistry you're doing/have trouble with, might be able to suggest some stuff...

SckizoBoy:

Cyfu:
So chemistry sucks, and I have to have it for 2 years.

*gasp* You should be ashamed!

The problem is that there's so much in chemistry that just doesn't make any sense to me and I have problems remembering how to calculate the different things because every calculation to figure out shit is the longest calculation you have ever seen!

Anyways, I really want to get a better grade than I have now(I have a 2 in chemistry and I want at least a 4) and I need get my shit together quick. So does anyone how any suggestions on how to get better? like any programs or something I could go through or anything? I'm really desperate :(

Thanks

Right, question time...

1) What level of chemistry? (e.g. NMR: spectral prediction; low-res interpretation; high-res interpretation; NOESY... TOCSY?!)
2) What type of chemistry? (physical/inorganic/organic/analytical)
3) How good are you at maths/physics/biology?
4) How're you being taught at the moment?
5) What materials are your institution giving you?

I think that's all for now... but generally speaking, other than rote memorisation and doing questions, not much you can do to get around it. Chemistry as a university subject is just too expansive to really say that 'here's a book that contains it all' or 'here's a program that'll teach it all' etc.

If you say which form of chemistry you're doing/have trouble with, might be able to suggest some stuff...

1)I'm in my second year in high school, so this is my first year with chemistry.
2)well, the basics of everything I guess. Organic, Acids and Bases, water and pH and all that.
3) I'm about average I guess. out of the three difficulties I can choose from at my school I'm taking the middle one. I'm also taking physics 1 and doing ok there.
4)I'm being thought with a teacher that uses the chemistry classes going through how to to the stuff we're learning at the moment (If that makes any sense :) and then get homework.
5)I can't remember all the names of that shit xD
We have quite a lot though. we have a experiment every other week.

EDIT:
I'm having problems with most of it really :(
Mole calculations I kind of understand. But I think I need to work with it more. Which might be the reason why I find chemistry so hard, because a lot is built on that.
solubility product(I'm not english so this word may be inaccurate) I had no fucking clue what was going on.
and now I'm having problems with the pH for weak acids and pOH for weak bases. The calculations are so fucking long and make no sense what so ever.

The only advice I can give is get a tutor, although I guess they can be expensive. I got one for my A-Level maths, having one-on-one time with a teacher is really useful, you can go through things at a slower pace and go over what you need to.

not sure how the education system works where you live but if you were in australia i would just advise you to fail it and focus on something else
over here nothing but the last 2 years of high school matter and at that point you get to elect which subjects you can study

For general advice, I would try to make sure you understand a concept before you just start entering things into equations without knowing why you're doing it. If you're just entering things into you're calculator without really knowing what you're doing, you'll have more trouble doing the problems, and newer concepts will be harder to learn, because you won't be able to apply your previous knowledge to new ideas. Try talking to you're teacher if you're not getting something, or if your teacher isn't very good at their job, look it up online (note, Wikipedia is not a very good resource for this, as science articles tend to not be written in a way so that they're easily understandable by people outside of that field).

Also, if you're having trouble, do more problems. There's no reason to limit yourself to just the problems you're assigned if you're struggling. The more problems you do, the better you are going to learn the material, period.

Anyway, more specifically, I think I might be able to help you with pH and pOH of weak acids and bases. I'm not sure exactly how much you know about this, so I'm just going to start from the beginning.

Strong acids and bases dissociate (seperate, basically) completely in water. For example, HCl will completely dissociate into H+ (well, H3O+ really, but it doesn't make much of a difference) and Cl- ions. Therefore, the concentration of H+ ions is going to be the same as the initial concentration of HCl, which you can then use to calculate the pH.

Weak acids and bases, on the other hand, only partially dissociate in water. For example, in water, some acetic acid (CH3CO2H) dissociates into CH3CO2- and H+ ions, and some of it doesn't. Basically, a weak acid dissolving in water is part of a reversible reaction, where as the reactants turn into products (the forward reaction), some of the products turn back into reactants (the reverse reaction). At a certain point, the rate of the forward and reverse reactions is the same, and the amount of products and reactants doesn't change. At this point, the reaction is said to be in equilibrium.

Now, the ratio of the products and reactants in a reversible reaction is always the same, regardless of how much of them you start with. This ration is the equilibrium constant, which for acids is K(a), and K(b) for bases (note, it should be a subscript instead of in parentheses). The equation for K(a) or K(b) is:

K(a) = (concentrations of products) / (concentration of reactants)

Now, for acetic acid, the chemical equation is:

CH3CO2H -> CH3CO2- + H+

For the calculation of K(a), the concentration of each part in either the products or reactants should be multiplied together. So, for acetic acid:

K(a) = ((Concentration of CH3CO2-) * (Concentration of H+)) / (Concentration of CH3CO2H)

So, everything except the concentration of H+ is known:

Concentration of H+ = (K(a) * (Concentration of CH3CO2H)) / (Concentration of CH3CO2)

Now, I'm guessing most of your problems are along the lines of "what is the pH of a 0.1 M acetic acid solution, where K(a) = 1.8 * 10^-5." To solve this, first, you need to determine what the concentrations of each chemical in the reaction. To do this, a table can be helpful. Because the change in concentration for each chemical is unknown, but each change in concentration is equal, we can use x to represent the change in concentration

CH3CO2H H+ CH3CO2-
Initial concentration 0.1 0 0
Final concentration 0.1 - x x x

Then, substitute the values in the table into the K(a) equation.

1.8 * 10^-5 = (x * x) / (0.1 - x) = x^2 / (0.1 - x)

Then, we try to get the equation in the form of a quadratic equation (ax^2 + bx + c = 0)

-x^2 + (1.8 * 10^-5)x ((1.8 * 10^-5) * 0.1) = 0

Then we can use the quadratic formula to solve for x.

x = 6.8 x 10^-4

Then, because the concentration of H+ = x, we can simply substitute x into the pH equation to find the pH of the solution.

pH = -log(6.8 x 10^-4) = 3.2

I hope that helps make things a little clearer, although you still should probably talk to your teacher (again, if they're any good at teaching).

ohnoitsabear:
For general advice, I would try to make sure you understand a concept before you just start entering things into equations without knowing why you're doing it. If you're just entering things into you're calculator without really knowing what you're doing, you'll have more trouble doing the problems, and newer concepts will be harder to learn, because you won't be able to apply your previous knowledge to new ideas. Try talking to you're teacher if you're not getting something, or if your teacher isn't very good at their job, look it up online (note, Wikipedia is not a very good resource for this, as science articles tend to not be written in a way so that they're easily understandable by people outside of that field).

Also, if you're having trouble, do more problems. There's no reason to limit yourself to just the problems you're assigned if you're struggling. The more problems you do, the better you are going to learn the material, period.

Anyway, more specifically, I think I might be able to help you with pH and pOH of weak acids and bases. I'm not sure exactly how much you know about this, so I'm just going to start from the beginning.

Strong acids and bases dissociate (seperate, basically) completely in water. For example, HCl will completely dissociate into H+ (well, H3O+ really, but it doesn't make much of a difference) and Cl- ions. Therefore, the concentration of H+ ions is going to be the same as the initial concentration of HCl, which you can then use to calculate the pH.

Weak acids and bases, on the other hand, only partially dissociate in water. For example, in water, some acetic acid (CH3CO2H) dissociates into CH3CO2- and H+ ions, and some of it doesn't. Basically, a weak acid dissolving in water is part of a reversible reaction, where as the reactants turn into products (the forward reaction), some of the products turn back into reactants (the reverse reaction). At a certain point, the rate of the forward and reverse reactions is the same, and the amount of products and reactants doesn't change. At this point, the reaction is said to be in equilibrium.

Now, the ratio of the products and reactants in a reversible reaction is always the same, regardless of how much of them you start with. This ration is the equilibrium constant, which for acids is K(a), and K(b) for bases (note, it should be a subscript instead of in parentheses). The equation for K(a) or K(b) is:

K(a) = (concentrations of products) / (concentration of reactants)

Now, for acetic acid, the chemical equation is:

CH3CO2H -> CH3CO2- + H+

For the calculation of K(a), the concentration of each part in either the products or reactants should be multiplied together. So, for acetic acid:

K(a) = ((Concentration of CH3CO2-) * (Concentration of H+)) / (Concentration of CH3CO2H)

So, everything except the concentration of H+ is known:

Concentration of H+ = (K(a) * (Concentration of CH3CO2H)) / (Concentration of CH3CO2)

Now, I'm guessing most of your problems are along the lines of "what is the pH of a 0.1 M acetic acid solution, where K(a) = 1.8 * 10^-5." To solve this, first, you need to determine what the concentrations of each chemical in the reaction. To do this, a table can be helpful. Because the change in concentration for each chemical is unknown, but each change in concentration is equal, we can use x to represent the change in concentration

CH3CO2H H+ CH3CO2-
Initial concentration 0.1 0 0
Final concentration 0.1 - x x x

Then, substitute the values in the table into the K(a) equation.

1.8 * 10^-5 = (x * x) / (0.1 - x) = x^2 / (0.1 - x)

Then, we try to get the equation in the form of a quadratic equation (ax^2 + bx + c = 0)

-x^2 + (1.8 * 10^-5)x ((1.8 * 10^-5) * 0.1) = 0

Then we can use the quadratic formula to solve for x.

x = 6.8 x 10^-4

Then, because the concentration of H+ = x, we can simply substitute x into the pH equation to find the pH of the solution.

pH = -log(6.8 x 10^-4) = 3.2

I hope that helps make things a little clearer, although you still should probably talk to your teacher (again, if they're any good at teaching).

Thanks, that actually precisely what I'm struggling with :) (Right, now anyways. If I've learned anything in the last 6 months with chemistry is that there's always something else, always!)

and before I go back to chemistry to study for the test, I have one question. Does chemistry become fun at any time? or better than being the bane of my existance?

Cyfu:
snip

Hummmm... mole calculations... I'm OK with... provided you don't get into the whole different concentrations experiment that tests rates of reaction... -_-

That said, I'll offer my advice whenever you need it (I'm a double grad, though I'm sure someone somewhere on Esc has a doctorate!) though you'll find my specialties are organic mechanisms & reactivity, MS & NMR analysis and complexation in inorganic.

Still...

Cyfu:
and before I go back to chemistry to study for the test, I have one question. Does chemistry become fun at any time? or better than being the bane of my existance?

It really depends on how you approach it/what you tend to like. I love organic chemistry, but hate physical. Can't get all that crap with Jablonski diagrams and quantum tunnelling and all that crap into my head. Give me a Michael addition and electron pushing, I'll gleefully set into it. Now, if that went over your head, sorry... but at the level where you are, there is still enough variation to know that you'll like parts of it much more than others. You can't force yourself to like it... can't do that with anything, but it may be that other interests will influence what you like in chemistry.

 

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