Chemical Forums

Chemistry Forums for Students => High School Chemistry Forum => Topic started by: idontunderstandthis on April 15, 2008, 06:29:20 AM

Title: unknown chemical
Post by: idontunderstandthis on April 15, 2008, 06:29:20 AM

Recently my chemistry teacher gave me an assignment.
We had to get an unknown substance. I got unknown substance P.

It was a blue solution. Therefore it was copper.
I did a flame test to confirm it. The flame turned green.
My friend (dont ask how he knows) knows that it must be copper sulphate or copper chloride.
I'm not so sure.

---Chemicals available---
1. Silver nitrate
2. Nitric acid
3. Hydrochloric acid
4. Barium chloride
5. Ammonium molybdate
6. Sulphuric acid
7. Potassium thiocyanate
8. Sodium oxalate
9. Sodium hydroxide

They are all diluted to 0.1M.


Can anyone help with this?

Title: Re: unknown chemical
Post by: Arkcon on April 15, 2008, 06:50:29 AM

Other chemicals give a green flame test.  And they are sometimes instructed to put blue food coloring in your test samples, to throw you off.

Title: Re: unknown chemical
Post by: Borek on April 15, 2008, 06:54:45 AM

Assuming it is copper sulfate - what will happen when you will mix it with each of the reagents you can use? Think in terms of precipitates and color changes.

Title: Re: unknown chemical
Post by: chiralic on April 15, 2008, 02:10:12 PM

On these links you find information about Flame Test:

http://chemistry.about.com/library/weekly/aa110401a.htm

Regards,

Chiralic