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HI all,
I did a search on this but didn't find the ansewr I was looking for. I need to make up 250ml, of 0.5 molar solution of Copper Sulfate but I only have Copper Sulfate Pentahydrate. Now I can easily make up a 0.5 molar solution of copper sulfate pentahydrate but can I use the pentahydrate to make up the copper sulfate and if so what calculations do i need to do? Hope that makes sense, any help muchly appreciated. OH It's for an evapouration prac fro year 8's.

Concentrations of solutions are based on their molecular weight.....so the molecular weight per litre gives you a 1M solution,then you work your desired concentration from that...it is copper sulfate solution just the pentahydrate not the anhydrous.The anhydrous solution would be made up on its molecular weight.

Example is NaOH...40g/litre is 1M

The MW of copper sulfate pentahydrate (CuSO₄.5H₂0) is 249.68, so you need 124.84g of CuSO₄.5H₂0 to make a 0.5M solution of copper sulfate.

If you were using CuSO₄ anhydrous you would need 79.81g to make up 0.5M solution.

Does that help?

Carol

YES! Thank You! So the 124.84 g is that for 1 litre?

Hi, copper Sulfte Pentahydrate, is purchased by us labbie because it has a longer shelf life. So it is fine to use. Check with the teachers first but you may need to add conc Sulfuric acid to this.

The Molecular weight is 249.68, For 500ml I use 62.5grms in 487.5 waterm add 12.5 of conc sulfuric acid to make up to 500ml for 0.5M.

Hope this helps

The sulfuric acid wasn't needed so the way I did it was weighed out 31.25 g of CuSO₄. 5H₂0 put it into a 250ml volumetric flask and added distilled water to the fill line. So do I have a 0.5 M soultion of Copper Sulfate? or a 0.5 M soltuion of Copper Sulfate Pentahydrate? Sorry to be a bother I just can't get my head around the 5 water molecules and if they will effect the concentration

Hi, If you use copper Sulfate Pentahydrate, crystals, then you have 0.5M copper sulfate Pentahydrate.

If you used copper sulfate, then you have 0.5M Copper sulfate.

Most of use use copper sulfate Pentahydrate, and we refer to it as copper sulfate. This may be how the confusion started.

Row,

The pentahydrate means that there are water molecules involved in making up the crystals. Lots of salts have water molecules combined with them when they form crystals. (Yes yes everybody else, this is just the basic explanation) When water is in CuSO4 crystals it makes them blue. When the CuSO4 is anhydrous it's white. So as long as you calculate the additional weight of the water when you are working out how much CuSO4 to put into water to make a solution you'll be fine, because you will still have a correct NET weight of CuSO4.

So the answer to your question is YES, you will have ended up with a Copper Sulphate solution, forget about the pentahydrate, coz that only refers to the crystalline state.

THANK YOU! Glad thats all cleard up. I thought I was right but I do have a tendency to doubt myself. Thanks again Ya'lll!

Thank you Kristin, for clarifying that with a nice, simple explanation (for those of us without proper training, let alone degrees!)

Happy to oblige!

Thanks for the thanks.

Molar mass of cuso4.5H2O is 249.68
Weight of a mole of copper sulfate pentahydrate is 249.68g.
If you weigh 249.68g of copper sulfate pentahydrate it contains one mole of cuso4 and 5moles of water.
To make a 0.5M cuso4 solution you need 0.5moles of cuso4 in one litre of solution. You can't seperate cuso4 from a pentahydrate. You have to weigh 124.84g of copper sulfate pentahydrate and dissolve in distilled water and add more water to make a litre. 0.5 mole of water comes with cuso4. It does not matter. It will go to the solution. As long as the solvent is water it does not matter.
Sujatha

Hi Sujatha,
Whereabouts is Kingswood in WA?

http://www.stdominics.nsw.edu.au/

Hello again,
I was just tidying up my CHem stor in preparation for a big delivery and I have a bottle of copper sulfate solution in my that was made up last year by a teacher (before the school had a labbie), it's of unknow concentraition an it seems to have gunge in it. What should I do with it? It's got kinda a slimy yellowish sediment in it , is it still ok to use or should I dispose of it?
I also have a bottle with what I think is iodine crystals in water, obviously they haven't dissolved very well and purple gas has formed in the bottle too, any suggestions on what I should do with this? . Again it was prepared by the same science teacher apparently he was trying to make iodine indicator without a recipie
Thanks

you could try filtering it to get rid of the gunge, and then using it for experiments where the exact concentration is not needed (eg reaction of aluminium foil in Copper sulphate)
jen

Or filter it, then evaporate it into crystals for easy storage and use them when you do the crystal making pracs (assuming you do that up there). It may have copper chloride mixed in with it as well. That sounds like something I ended up with here, in which case you just need to dispose of it. Everything is easier in solid form though, I reckon.

Good day all

In The Laboratory on Pg 33, to make Copper Sulphate 0.2M solution requires the addition of 15mL of 0.1M Sulphuric acid.
On pg 37 to make a saturated solution, no sulphuric acid is added.

I also have a typed out list titled Preparing Solutions possibly downloaded from here, that gives the directions for both a 0.1M and a 1M solution and neither mention requiring the acid.

So my question is.........does Copper Sulphate solution require the addition of Sulfuric acid? is it dependant on the use?

Thanks

also when I look on the SDS for various strengths under the composition heading there is no mention of acid

I have never added sulfuric acid! never. and I have been a chemist for over 30 years, a labtech for 14 years.