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Help Making Ferric Solutions

Posted: 15 Aug 2014, 09:03
by smiley
I've been asked to make a 1M ferric solution, for use with galvanic cells. I tried Ferric chloride, and it is simply not possible to dissolve that much powder!

Any suggestions? Is it even possible to make a 1M Ferric solution? Help. :cry2:

Re: Help Making Ferric Solutions

Posted: 15 Aug 2014, 09:13
by lada
I don't know, but why do teachers always "need" such high concentration.
I try to swap for 0.1-05M solutions which will give them same results.
Just make sure all solutions are same conc, if they take measurements.
Lada

Re: Help Making Ferric Solutions

Posted: 15 Aug 2014, 09:42
by fibreweb
I think they need that higher concentration because "that is what the book said"
how well do we know that what is in the book does not always work!
The people writing the book sometimes hasn't tried to actually do the prac.
In thoery it should work but not in practice.

Re: Help Making Ferric Solutions

Posted: 15 Aug 2014, 10:03
by lada
How true.
I was ask to make up 1L of AgNO3 for a displacement reaction.
Put coiled Cu wire in large test tube and cover with solution of silver nitrate. 27 students of 25ml solution about 700ml needed.
I gave them micro tubes small length of Cu wire and 3ml of solution each. Guess what, it worked very well and with only 80ml AgNO3 needed.

Re: Help Making Ferric Solutions

Posted: 15 Aug 2014, 10:15
by smiley
We we are doing Galvanic cells. I have seen it work with other metals - Mg, Al etc. I think the problem here is that the teacher thought "Hey, I'll add in another metal!" but it seems to be physically not possible to make a 1M solution of that metal ion.

Re: Help Making Ferric Solutions

Posted: 15 Aug 2014, 11:37
by rae
We do this prac using 1M solutions. CuSO4, ZnSO4, Al(NO3)2 and FeSO4. Not ferric chloride.

Re: Help Making Ferric Solutions

Posted: 15 Aug 2014, 11:40
by smiley
Thanks Rae, will give that a try!

Re: Help Making Ferric Solutions

Posted: 15 Aug 2014, 11:43
by rae
Smiley, we also recycle it. I have bottles labelled for "electrolysis only" and use it a few times.

Re: Help Making Ferric Solutions

Posted: 15 Aug 2014, 12:53
by MariaC
Me too Rae, saves throwing and remaking!

Re: Help Making Ferric Solutions

Posted: 15 Aug 2014, 13:21
by smiley
Oh..OK..I thought that it becomes denatured after use, coz it loses it's ions, so then it has to be chucked because it won't give an accurate reading for the next kid. That's what the chem teachers told me this morning!

We give ours target voltages and they have to work out the dilutions etc.

Re: Help Making Ferric Solutions

Posted: 15 Aug 2014, 13:26
by rae
You are probably right Smiley however my chem teacher doesn't mind and that's why I do it.

Re: Help Making Ferric Solutions

Posted: 15 Aug 2014, 14:12
by smiley
Well, definitely cheaper & easier your way. :thumbup: