Ways to get copper into water?

[Alkaline Earth]

I am doing a science fair project on phytoremediation, which is how plants can take out the bad things in their environment. I am using duckweed in a container with water, the duckweed has been growing for about a week, so much so that it has already covered the entire surface of the 8in by 8in container it is in. I think it is time to start distributing my duckweed into other containers. Each container will have a different amount of copper in it, and every day I will test the water to see if the copper is less than it was the day before.

My problem is how do I get the copper into the water? My teacher suggest putting copper sulfate into the water, but I am trying to find other ways I can do it. Perhaps there is a household item that contains copper I could use? I dont want to have to order it on Amazon, but I will if I have to.

Please any suggestions.

[Magister Militum Flavius Aetius]

Hmm... good question. You want to use something that won't really chemically react with the water, but the hydrogen bonds will pull the Copper and Oxygen into their separate ions. Oxodized Copper would work for that (you wouldn't have to worry about a double replacement reaction and Oxygen forms H-bonds.)

Easy way to oxidize copper would be to get some copper wire, throw it in a metal pan of water, and then do some electrolysis of water I think. But I'm not sure on that, so someone please correct me if I'm wrong here.

[Kyriakos]

If this was my experiment i would inject copper2 sulphate crystals into the chitin armor of a scarab, just below its inverted triangle bit before the pseudo-wings, and then leave it to slowly drown in the water. It can be used as a pesticide, and still is- i think.

But that is just me, cause i am secretly enamoured with watching things suffer

[Col. Tartleton]

Won't copper kill the plants?

[Logios]

I think you should follow your teachers advice about the copper sulfate, as this has a bright blue colour. You could of course pick another copper salt. The best way would be to carefully weigh the needed amount of copper sulfate and dissolve it in distilled water in a volumetric flask. You can then pippete various amounts of the stock solution into your test containers. Make some calculations and initial experiments to hit a concentration range which both gives you a bright colour of the water in the test containers, and a copper concentration that the duckweed can actually work with.
Remember to bring the stock solution to the science fair, and if you are are using something "bubbly" as a pH buffer like sodium bicarbonate, then bring that too for a demonstration.
Which analytical method are you using for the daily samples? If this is done by AAS or LIC in a remote lab, you could demonstrate the priciple of it at the fair by showing how the copper solutions can turn a gas flame green.

Won't copper kill the plants?

A too high concentration would yes, and trees can be killed with copper nails, but all plants need a little bit of copper for their chlorophyl. It is all about hitting the right concentration.

[Alkaline Earth]

i am just doing it at my house without any science-y stuff. i have a couple food containers that i cleaned and put tap water in, put some duckweed seed into it, and its growing pretty nicely. i am going to home depot to get the copper sulfate today. what is this pH buffer u are speaking of? and u saying I should test the copper in a container with water but no duckweed to see its color, when would I know what is too much that it would kill it?

edit:

ok i bought some zep root kill, it is 99.9% copper sulfate pentahydrate for 10$ at home depot. the blue crystals look like meth so i am a bit skeptical (jk).

I guess I will start my project

[Logios]

I am doing a science fair project

I am assuming you have to show-and-tell or present it in a way where blue bubbling liquids and green flames could come handy as visual effects

every day I will test the water to see if the copper is less than it was the day before.

Which test method are you using? Do you run the test immediately or do you just sample every day and test everything in the end?

what is this pH buffer u are speaking of?

Copper Sulfate has an acidic reaction in water, you could read up on why to provide a clever answer if someone asks at the presentation. You could test with a pH strip to see if the amount you work with is large enough for this effect to be significant. I assume that duckweed grows best at a pH around 7, and to counter the acidic reaction of the copper sulfate you could add a buffer - a compound that is good at maitaining a certain pH range. Sodium bicarbonate (baking powder) might do the trick. If you add the bicarbonate to the stock solution when presenting (to show how you made it), you will have something that is both bright blue and bubbling.

and u saying I should test the copper in a container with water but no duckweed to see its color, when would I know what is too much that it would kill it?

Yes, you need to find a copper concentration that will not kill the duckweed or hamper its growth too much, but at the same time you will want to show the different colour intesities in containers with different copper concentrations.

[Alkaline Earth]

so i am doing 200g of copper sulfate per 100cubic inch of water. this is extrapolated from what farmers use for lakes (6Ibs per acre of water). in my test container which contains 7 cups of water (very close to 100cubic inches) i put in 200g of copper sulfate. i did a litmus test and it was red. i added baking soda and its still reddish. i add baking soda, wait 30 min, then add again until I get to a pH of 7.

so far, it is still red, but have only done 3 litmus tests.

once i get the ratio, i will move onto my next step, which is moving the duckweed fronds from my source container 3 other containers that have had the copper sulfate/baking soda mixture in it for over an hour ( so the chemical reaction doesnt kill the plant)

will update tomorrow

[Elfdude]

I think the problem here is that using copper II sulfate will conflate your results. Plants are great at removing sulfates and nitrates from water and while they need a bit of copper usually it's not a big deal. You need to figure out a way to test for the copper or do some molarity calculations to figure out what's actually happening. You will also have issues with the long term nature in that you will be adding water which could also skew your results. On the other hand the ability to break down sulfates and other organic chemicals is going to be more interesting then the plant's use of metalic ions.