Help with Chemistry please!

Wizegui

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I don't know if this is where I post my rather stupid question, but here it goes (this is a Common Ion Effect question):

Silver oxide dissolves according to the reaction:

Ag2O + H2O <=> 2Ag+ + 2 OH-

If the Ksp=[Ag+][OH-] = 2.0*10^-6 for AgOH, how many moles of Ag2O will dissolve in 2.0L of a solution having [OH] = 1.0*10^-3M ?

Any sort of (relevant) help would be greatly appreciated.
 
*eyes glaze over*

You asked this about four years late...It all looks horribly familiar though...
 
Here's the information you should keep in mind:

[Ag?] is the concentration of silver ions in the solution.
[OH?] is the concentration of hydroxide ions in the solution.

[OH?] *starts* at 1.0?10??M, and will increase as the Ag?O dissolves.

You need to find a way to express [Ag?]?[OH?] as a function of how much Ag?O has dissolved, and set that equal to Ksp.
 
Oh geez, I'm only in regular Chem, not even AP, that's so over my head. lol
 
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hahaha I'm an art major :D
 
Damn asked a year too late, as I was in AP Chem last year. If you're in AP, take a look at your equation sheet, as there should be some relevant equation there.

I'll take a look at my old stuff and see if I can help you out as soon as I get back to my house.

EDIT: In the meantime, you might be able to figure it out by relating your problem to one of these:
http://users.stlcc.edu/gkrishnan/solubilityproduct.html
 
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Thanks for the help guys. So far, I've read through the stuff that seems like the easier common ion effect problems. The problem is that these problems were given us a few days before the test. Unfortunately, not only does he not have the answer sheet with him, but he also needs to test us on these problems due to our rather slow pace. I get the basics of Common Ion Effect (the part that was covered in the textbook, but when it comes to problems involving the solubility product and concentrations, I'm hopeless).

Here's the information you should keep in mind:

[Ag?] is the concentration of silver ions in the solution.
[OH?] is the concentration of hydroxide ions in the solution.

[OH?] *starts* at 1.0?10??M, and will increase as the Ag?O dissolves.

You need to find a way to express [Ag?]?[OH?] as a function of how much Ag?O has dissolved, and set that equal to Ksp.

All I've figured out how to do is square root the Ksp of AgOH to find the concentration of Ag+. After that, I'm completely lost....

Also, I'm currently just taking a normal Chemistry 12 class. I'm pretty sure that they'll know how to do all this. Can anyone provide me with the steps of completing a problem like this? Again, thanks for the replies.
 
Unfortunately for you, Wizegui, the resident FG member with a PhD in chemistry is far more devoted to organic than physical chemistry...

It's been so long since I tackled a question anything like this, I'd forgotten that the Common Ion Effect even existed.

Suffice to say the number you end up with has to be very small. Silver oxide is all but insoluble in distilled water, let alone an already alkaline solution...
 
All I've figured out how to do is square root the Ksp of AgOH to find the concentration of Ag+. After that, I'm completely lost....

Taking the square root of Ksp doesn't work in this case because the concentrations of silver ions and hydroxide ions aren't the same. The key here is finding a way to write [OH?] in terms of [Ag?].
 
Hmm, I was doing this last year, but I don't have my book anymore.

Don't you just need to use a triangle to work out which value needs to be divided/multiplied by which other value?
 
Silver oxide dissolves according to the reaction:

Ag2O + H2O <=> 2Ag+ + 2 OH-

If the Ksp=[Ag+][OH-] = 2.0*10^-6 for AgOH, how many moles of Ag2O will dissolve in 2.0L of a solution having [OH] = 1.0*10^-3M ?

Come along now, I don't need to use my doctoral studies in physical chemistry to solve this.

You already know [OH-] = 10^-3, and that [Ag+][OH-] = 2.0*10^-6.

How hard, then, is it to figure out that the maximum concentration of silver ions ([Ag+]) is 2.0*10^-3 Molar? That's just arithmetic.

How many moles of silver oxide will dissolve in 2.0L of solution to give you 2.0*10^-3 Molar silver concentration? Well, I'm pretty sure it's 2.0 mmol - how convenient that your professor should give you 2.0L of solution in which to dissolve an oxide yielding two equivalents of analyte.

EDIT: Yeah, 2.0 mmol in 2.0L of solvent happens to be about 23mg in 100mL - which is far above the actual solubility of silver oxide - 1.3mg in 100mL.
 
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How hard, then, is it to figure out that the maximum concentration of silver ions ([Ag+]) is 2.0*10^-3 Molar? That's just arithmetic.

Might want to revisit your old notes again: if the Ag? concentration is 2?10??M, that would make the OH? concentration 3?10??M. ;)
 
I did 'O' level Chemistry, in 1971 - I got an 'E' which was a pass (A, C and E = passes and F and Unclassified were fails)...

I am not helping am I?
 
Y'mean there's two of us?

Now all we need is an inorganic chemist (with JAZZ HANDS!) to complete the set!

Well, one of us is a PhD organic chemist and the other is a third year MD/PhD student. I'm not quite sure where I'll be doing my research, but it most likely won't be organic chemistry and will probably be PChem or possibly inorganic, though let's not forget analytical chemists - they're people too.
 
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