Determining the formula for a hydrate - Tilted Forum Project Discussion Community

Slavakion · 09-16-2004, 03:48 PM

We got this interesting lab today in AP Chem. Pretty much, you have to figure out the formula for copper chloride (unknown whether it's I or II) by devising your own procedure. The only hint you're given is that you can use .1 mol AgNO3. There is only 1.5g copper chloride.

I was thinking that you could mix the silver nitrate with the copper chloride so that silver chloride would precipitate. You can filter that out, mass it, and then find the mass of the Cl. I'm not sure what to do with the copper nitrate, though. I suppose you could figure out the volume of the c chloride sample, and from there find the density. I have a feeling that it'll have something to do with the limiting reactant... or I'm making stuff up that sounds good to me

Hmm... we'll hopefully talk about this more in class.

The point of this post is not for you to tell me the answer, but rather to tell me if I'm on the right track. And if that offends your delicate academic sensibilities, so be it.

Amano · 09-16-2004, 11:10 PM

You might have some trouble because in any purifucation there is some loss of product. So you wouldn't be able to get the theoretical amount of product in your experiment. Cu(I) will produce a certain amount of product, Cu(II) will produce another certain amount. But if you yield product that is less than the theoretical values for both I and II, you won't know which one you had to begin with.

I think that i've come up with a slightly better protocol that involves the concept of a limiting reagent. But as requested, I won't list it.

Slavakion · 09-17-2004, 02:20 AM

Well, what do you mean by purification? I was thinking of either gravity or suction filtering (which we just used in a lab). Those are pretty accurate. Eh, it's 6 AM.

Slavakion · 09-17-2004, 07:34 PM

Okay, the one I'm sticking with is as follows. Forgive the vagueness.

Mix the silver nitrate with copper chloride to precipitate silver chloride.
Use suction filter to separate silver chloride
Mass silver chloride
Use stoichiometry to find copper (yeah, it's possible. I just have to hash it out)
*optional*
Boil copper nitrate solution to leave salt
Mass copper nitrate salt
Use stoichiometry

Teach said that the first four steps were right, and that boilage was unnecessary.

Now that I'm through with that, I'm interested in what your idea was.

09-16-2004, 03:48 PM	#1 (permalink)
Slavakion Mjollnir Incarnate Location: Lost in thought	Determining the formula for a hydrate We got this interesting lab today in AP Chem. Pretty much, you have to figure out the formula for copper chloride (unknown whether it's I or II) by devising your own procedure. The only hint you're given is that you can use .1 mol AgNO3. There is only 1.5g copper chloride. I was thinking that you could mix the silver nitrate with the copper chloride so that silver chloride would precipitate. You can filter that out, mass it, and then find the mass of the Cl. I'm not sure what to do with the copper nitrate, though. I suppose you could figure out the volume of the c chloride sample, and from there find the density. I have a feeling that it'll have something to do with the limiting reactant... or I'm making stuff up that sounds good to me Hmm... we'll hopefully talk about this more in class. The point of this post is not for you to tell me the answer, but rather to tell me if I'm on the right track. And if that offends your delicate academic sensibilities, so be it.

09-16-2004, 11:10 PM	#2 (permalink)
Amano Insane	You might have some trouble because in any purifucation there is some loss of product. So you wouldn't be able to get the theoretical amount of product in your experiment. Cu(I) will produce a certain amount of product, Cu(II) will produce another certain amount. But if you yield product that is less than the theoretical values for both I and II, you won't know which one you had to begin with. I think that i've come up with a slightly better protocol that involves the concept of a limiting reagent. But as requested, I won't list it.

09-17-2004, 02:20 AM	#3 (permalink)
Slavakion Mjollnir Incarnate Location: Lost in thought	Well, what do you mean by purification? I was thinking of either gravity or suction filtering (which we just used in a lab). Those are pretty accurate. Eh, it's 6 AM.

09-17-2004, 07:34 PM	#4 (permalink)
Slavakion Mjollnir Incarnate Location: Lost in thought	Okay, the one I'm sticking with is as follows. Forgive the vagueness. Mix the silver nitrate with copper chloride to precipitate silver chloride. Use suction filter to separate silver chloride Mass silver chloride Use stoichiometry to find copper (yeah, it's possible. I just have to hash it out) optional Boil copper nitrate solution to leave salt Mass copper nitrate salt Use stoichiometry Teach said that the first four steps were right, and that boilage was unnecessary. Now that I'm through with that, I'm interested in what your idea was.