[RDX]

I have here some root killer, which is copper pentahydrate mixed with copper sulphate. My goal is to make pure copper sulphate crystals. I know I can heat up the pentahydrate to release some of the water inside. I just can't tell by the color if I've released enough. My question is, what should I study to begin to understand how to determine if this is copper sulphate or copper pentahydrate, because they look very similar.

[Arkcon]

You'll have to re-read what you've read.  Copper pentahydrate doesn't exist.  Copper sulfate usually appears as copper sulfate pentahydrate.  So you'll have to start there, and re-ask what you really need to know.

[RDX]

What do I need to study to be able to determine if something is copper sulphate versus copper sulphate pentahydrate. Titration? Or another chemical analysis, and if so..what?

p.s. Why was this moved from the chemical analysis forums?

[AWK]

Color is sufficient. Anhydrous CuSO₄ ia almost white, hydrate is deep blue.

[RDX]

I've already done that, but how do I know if I've added too much water, making pentahydrate? Remember, the two look very similar, although the pentahydrate is little bit darker, from what I remember. This is where my question comes in: What do I need to study to understand what something is composed of.

Sure, I could take a sample of real copper sulphate and compare my experimental substance...but I feel there's a more educated way to learn..

Thanks for the replies.


Could I leave the anhydrous CuSO4 out in the open for a while until it attracts the natural H2O in the air? Would that form Copper Sulphate?

[Borek]

Please pay attention to what you write, as it is so ambiguous half of the answering is guessing what you really mean.

the two look very similar

Which two, anhydrous copper sulfate and copper sulfate pentahydrate? Nope, they look quite distinct.

Could I leave the anhydrous CuSO4 out in the open for a while until it attracts the natural H2O in the air? Would that form Copper Sulphate?

So you are asking if leaving copper sulfate in the air will produce copper sulfate? You have to be precise in what you mean. I guess you are asking whether leaving anhydrous copper sulfate in the air will produce copper sulfate pentahydrate. Yes, that's the way it works.

[RDX]

No, I'm talking about anhydrous copper sulphate and copper sulphate pentahydrate..


And I asked:
 "Could I leave the anhydrous CuSO4 out in the open for a while until it attracts the natural H2O in the air? Would that form Copper Sulphate?"

Still wondering how I would determine the difference between CuSO4 and CuSO4.5H2O via chemical analysis, like titration or something.

Why does the CuSO4(a) pick up so much H2O just by sitting idle? If that was the case, then why isn't my stash of CuSO4 crystals turning into CuSO4.5H2O....OR is it?


So, I've heated CuSO4.5H2O and made CuSO4(a). it's slowly turning a to a sky blue, as it's picking up the H2O. When is it sufficient to say it is just CuSO4 and not CuSO4(a) or CuSO4.5H2O? And can someone please explain what I should study to learn how to verify this myself thru some sort of analysis. Thank you for the replies.

[AWK]

https://wiki2.org/en/Copper(II)_sulfate+Newton

[RDX]

I read the whole thing, that's twice I've done that in my life. No where could I find anything that states how to synthesize CuSO4 from CuSO4.5H2O.

I'm not giving up...

[AWK]

Really?
"and the final water molecule at 200 °C (392 °F)"

[Borek]

"Could I leave the anhydrous CuSO4 out in the open for a while until it attracts the natural H2O in the air? Would that form Copper Sulphate?"

You are missing the point - anhydrous copper sulfate is still a copper sulfate. If you want to make a distinction you have to list the with their full names, which you didn't. What would be formed is not a "copper sulfate" but "copper sulfate pentahydrate".

Still wondering how I would determine the difference between CuSO4 and CuSO4.5H2O via chemical analysis, like titration or something.

First of all - it is enough to look at them, as they are quite different (which we told you several times).

Analytically there are many ways of determining how much water is in the sample. You can weight it before and after a roasting, as roasting removes water. You can weight the sample, dissolve it and titrate to check how many moles of copper (or sulfates) are present, then calculate amount the amount of water from the difference. You can try the latter approach but with any method that allows the determination of the amount of copper/sulfate (like spectroscopy).

Why does the CuSO4(a) pick up so much H2O just by sitting idle? If that was the case, then why isn't my stash of CuSO4 crystals turning into CuSO4.5H2O....OR is it?

Copper cation has a great affinity to water molecules. Every sample of anhydrous copper sulfate tries to get water from the air. Depending on the humidity it will absorb water up to becoming pentahydrate (what we call pentahydrate rarely contains exactly stoichiometric amount of water, it is typically a bit on a dry side). Your anhydrous sulfate does absorb water, just - if it is kept in the closed jar or bag - does it slowly. Leave it open and the process will speed up.

So, I've heated CuSO4.5H2O and made CuSO4(a). it's slowly turning a to a sky blue, as it's picking up the H2O. When is it sufficient to say it is just CuSO4 and not CuSO4(a) or CuSO4.5H2O? And can someone please explain what I should study to learn how to verify this myself thru some sort of analysis. Thank you for the replies.

Again - asking "when it is just CuSO₄" is meaningless. Sometimes it is an anhydrous copper sulfate, sometimes it is a copper sulfate pentahydrate, sometimes it is a copper sulfate tetrahydrate, sometimes it is an unspecified hydrate - but at any time each of these can be called "copper sulfate", so it is a copper sulfate all the time.