monolog

17 minutes ago, hypervalent_iodine said:

If you truly cannot figure out what the acid and conjugate base

When I asked I was told the brackets are there to indicate whatever. Well, I'm not gonna waste my time here while you circle jerk simple questions between yourselves. Wanna help people? Straight forward do it. Wanna use this forum to treat strangers the way you can't treat your students? I don't need that shit. Tutoring for 9 years? That sure explains it.

Not yet, I can't. But I will.

Or maybe I won't. I don't know how to get to those values. I don't even know which is [A^-] and which is [HA]. From the time management point of view it's not fruitful to waste time trying to do some juggling patchwork just to earn another point in this assignment. It's actually ridiculous to waste 2 days on something I could learn in 20 minutes with a private tutor. It's definitely better to move on to geology and make sure I excel in that one as I can actually learn the subject on my own. 

18 minutes ago, hypervalent_iodine said:

particularly since once you add the two volumes together the concentrations change

I'll try to figure that out.

1 minute ago, hypervalent_iodine said:

There are not a lot of hard and fast rules with figuring it out. There are some things you should know. Organic acids tend to be weak. Carboxylic acids, for example. Ammonia is a good example of a weak base. Strong acids you encounter most are things like HCl, and H2SO4. Strong bases you encounter at this level are frequently hydroxides, like NaOH. Generally though, whether or not you are dealing with a weak acid or base should be implicit in the question. If they give you a Ka or Kb, it’s fair to assume you’re dealing with a weak acid or base. You can also tell by looking at the equivalence points on titration curves, if given.

These are good guidelines, thank you. I'll google more on it, but for now I'll be going back to the assignment. Have a good day.

27 minutes ago, studiot said:

Now can you attempt Hypervalent Iodine's questions?

 

I will try. Have a good day.

9 minutes ago, studiot said:

And it has achieved its objective.

So did my false indignation. 

11 minutes ago, studiot said:

A weak acid or base is one which is only partially dissociated into ions in solution.

I definitely lack basic knowledge. How do I know if a compound partially or fully dissociates into ions in a solution? What in its formulae gives me that information?

1 minute ago, studiot said:

Please confirm you know what weak and strong mean in this context (by telling us the difference)

I wouldn't be here if I knew. Being confronted with my ignorance does not help. Explaining things to me, does.

This is what I did:

"Adding 30ml of NaOH gives us a 130ml solution. therefore:"

29 minutes ago, hypervalent_iodine said:

I don’t have time to watch the whole video, but my guess from the title that it does answer most of it except perhaps b, which is where you need the HH equation. If you know how to use the HH equation, then you’ll know the two values you need to determine are [HA] and [A-]. Do you know which species those correspond to in your question? Do you know how to work them out with the information you are given?

He actually uses the HH equation to find the pH.
Honestly, I don't know which species those correspond to in my equation. Would you explain it to me?
Luckily the value for both is 0,769, so I end up with log1 in the HH equation. The pH is 4.74. I hope I got it right.

22 hours ago, studiot said:

and did you bother with the lecture I appended?

Hi. I think my posts are limited to 5 daily, that's why I didn't reply. Yes, I did read it. As hypervalent_iodine says, I'm lacking too much fundamental knowledge. De-synced communication won't really help me right now. Thanks for your time anyway. I do appreciate you putting in the effort.

22 hours ago, hypervalent_iodine said:

At the moment it sounds like you are missing a lot of fundamental knowledge, and certainly too much to explain over a forum such as this. I can’t really give a step by step guide in this case, since it appears that you need an entire module’s worth of information given to you. You are better off studying this from the resources you already have had provided to you, and coming here with specific queries if something isn’t making sense. I realise this isn’t what it want, but it’s the best I can offer short of simply doing the work for you (which we do not do here).

You are right. I think I need a private tutor to help me at this point. I did find, however, a very helpful video which I believe will help me answer (b) and (c). Here it is: 

I thing I can solve the problem now. It does address the exact same problem, doesn't it?
Anyway, thank you very much for your time. I will keep this forum in mind, and also your recommendations. Best regards.

This is the equation, right?
pH = pK_a + log₁₀ ([A^-]/[HA])
How does this: NaOH + CH3COOH → CH3COONa + H2O, translate into values in the equation? What does [A^-] and [HA] stand for?

Replying to Studiot:

Hi. Thanks for your time.

You asked for the equation and I gave you a reaction going to completion, which I believe is the answer to (a). I don't know how to put that in a equation.

Does sodium acetate precipitate out? I don't know. All I have is the given info.

If not what does actually happen? An acid and a base mix, but i don't even know how to identify an acid and a base without looking up the compounds online, meaning I'm in trouble when the exam comes.

Do you know what  Data: K_a = 1,80 × 10^-5  means? It's the acidity constant, but I honestly don't know what to do with it.

Have you done any reaction kinetics? No.

Are you familiar with the following equations? No. [H₃O⁺] , [H⁺] and [OH^-] are exchanged somehow, but I don't know what exchanges with what nor why (electronegativity?).

In sum, I don't think I can learn this on my own in time to finish this assignment and get a good grade. Will be needing a private tutor. Biology, geology and statistics, I can learn those on my own. Chemistry, no way.

If you think you can explain the basic rules behind the [H⁺] [OH^-] transfers so I can try and make the calculations, great. If not, thanks anyway.

10 hours ago, hypervalent_iodine said:

Are you familiar with the Henderson Hasselbach equation at all?

Hi, and thanks for taking the time to help me.

No, I am not familiar with it. I'll look it up now.
I do have literature given by the university, but with all of the classes' assignments piling up I didn't have time to study it. Acid-base equilibrium, titration, energy reactions, entropy, and Gibbs energy are the subjects I have fallen behind on. In order to succeed in this assignment I need to go straight to the point (I'll go through the whole semester later in preparation for the exam).

What do I need to focus on in order to answer these questions? Can you give me a step by step guide?

Thanks in advance.

This is the equation, right?

How does this: NaOH + CH3COOH → CH3COONa + H2O, translate into values in the equation? What does [A^-] and [HA] stand for?
 

NaOH + CH₃COOH → CH₃COONa + H₂O

I have read it. I'm looking to be guided, maybe get a step by step explanation of what is going on and what to do so I can answer the questions. Got time for that? I would appreciate it.

Part a is done, yes. How do I find the pH of any solution? 

Hi. I'm doing a chemistry assignment in which I'm having difficulties. I am on a open university course (Environmental Sciences, first year) and never had chemistry in high-school (coming from the services area), therefore I need some assistance. Whatever help i get is welcomed.
This is it:
A solution of 100 cm³ of acetic acid (CH₃COOH) with a concentration of 0.2 mol / L was titrated with aqueous sodium hydroxide solution (NaOH) at a concentration of 0.1 mol / L.
a) Write the chemical reaction that translates the titration.
b) What is the pH of the solution after adding 30mL of NaOH
c) In a titration what is the meaning of the expression "point of equivalence"? For the given example, calculate the volume of titrant needed to reach this point as well as the pH value.
Data: K_a = 1,80 × 10^-5

Thanks in advance.