2M copper sulfate

[lizzieb]

Hello to all you knowledgeable people out there,

I've found some discrepancies between the The Laboratory's recipe and the old hand written/typed recipes for making up 2M copper sulfate. The 'bible' says to use dilute 0.1 sulfuric acid, and the typed noted use Conc. It seems to me that'll be quite a big difference!

What do you use?

[Sassi]

I use dilute!

Sass

[Robbie]

As I understand it, the acid is added to clear the solution so it is not murky. Therefore, I make up the solution with the copper sulfate first and then just add how ever much sulfuric acid is needed to clear the solution. I don't think the molarity is critical - just so it does the job!

Robbie

[Mother]

I use Conc.Sulfuric Acid,if cloudy.If not,I don't use anything
Cheers
Mother

[Labbie]

I use Conc also.

[lizzieb]

Thanks everyone for your answers.

Why is it sometimes cloudy and not others?

[Ocker]

It's the impurities in the Cu SO4 that make it cloudy
Now off the top of my head I think 1M is close to saturated will consult Book!

[rae]

Ocker I think youre right. I did a quick look up and a saturated solution of CuSO4 is 22.3g/100ml.

The MW of CuSO4 is 249.7g therefore 1M is 249.7g/1L

Which works out at is 24.97g/100ml and 2M is nearly 50g /100ml. I would call that SUPER saturated.
Are my calculations and reasoning correct??


LizzieB
How did you make up the 2M solution?? I just checked "The Laboratory"are you sure you didn't mean a 0.2M solution??

[Ocker]

I Concur but any extra will just form crystals in bottom of bottle!

[Ocean Breeze]

2 M/L Cu SO4 .
When would a conc of 2M be required?

I, like Ocker am at saturation point at 1 M/L ish.

Anything else is just saturated.

[lizzieb]

Sorry everybody - am just catching up, and yes, there's a story to tell ....
Tuesday (when I posted this originally), I was getting organised for my final Cert lll prac. it's been quiet here, so I was looking through all my solutions for something that needed refilling. Found the 2M CuSO₄ bottle, and then checked The Laboratory - hence the query about the acid.
Now of course you've all figured out what happened next - it didn't dissolve! Actually it was a great demonstration - I went to my SI Data book, and found that a saturated solution is only 22g/100mL. Why do I have a 2M bottle - good question. There's been a succession of casual and untrained science assistants in this job, including me!
It was an interesting exercise, and good to realise that these days I know where to find the answers. That's mainly due to all of you, especially my local network and mentors, and what I've learnt here - so thank you all - though the more I learn, the more I realise how much there is yet to learn....
The best news is that I've now been signed off on all my Cert lll modules - Hooray!

Now if only the Uni course I started this year was that easy!

[NTrivedi]

Hi All,

I came across this request last year for 2 M CuSO4 Solution.

If you look at solubility data on
http://encyclopedia.thefreedictionary.c ... lity+table
At 20 deg C it is 32 gms/100 ml and
at 30 deg C 37.8gms/100 ml.


Now looking at molecular weight and solubility data
I think it is possible to prepare solution with maximum concentration of
1.28 M at 20 deg C and
1.51 M at 30 deg C.
I think to be on safe side we can safely prepare 1.25 M solution
assuming minimum room temperature of around 20 deg C.

I hope it helps.

Cheers
NT

[gillegan]

I Concur but any extra will just form crystals in bottom of bottle!

Speaking of crystals, Ive got a bunch of test tubes with CuSO4 crystals stuck fast at the bottom and no idea how to get them out. A few came loose with a vigorous shaking but most are stuck fast and resisting the test tube brush and and even a probe only gets a couple of bits out.
Any advice would be much appreciated.

[Ocker]

Try Hot water!

[J]

Hot water is the go!

Sometimes may need to have a couple of goes at it, but hot water definitely does the trick.

Julie

[RosalieM]

put some hot water in the tubes and then sit the tubes in a beaker of water and then sit the beaker on your hotplate to create a hot water bath might help as well.