Copper

Answer to Write the formula for copper(II) sulfate More on chegg.com

Ok, well if we subtract the weight of the empty crucible, you started with 1.04 grams of hydrated copper sulphate. And somehow you ended up with 1.33 grams of "anhydrous" copper sulphate? Sorry, but that's impossible. If you are absolutely sure that nothing else was somehow dropped into the crucible, then I suspect a weighing error must have occurred. Perhaps the balance wasn't reading zero (it wasn't tared) when you weighed the crucible with the hydrated copper sulphate in it. Then, once the experiment was complete, if you reweighed it with the balance actually at zero (properly tared) then you could have easily read off a weight which was more than you thought you started with. In any case, the actual formula of hydrated copper sulphate is CuSO4.5H20. The molar mass of this is 249.5, whereas the molar mass of anhydrous copper sulphate is 159.5. The difference between them is 90. This translates to 36.1% water by weight. So your 1.04 grams of hydrated copper sulphate, if completely converted to the anhydrous form, should be reduced in mass by 36.1%, making it now weigh 0.665 grams. That answer is precisely half the weight you actually ended up with (0.665 x 2 = 1.33). This may be a coincidence, but it may also be that somewhere in your calculations, you somehow ended up multiplying your answer by 2? Not sure how, but it would explain the result. More on reddit.com

I’ve never seen 12 ml/gallon sulfuric acid used - that’s absurd! A typical high-throw bath would contain 10-12% by volume (v/v) of a 95-98% by weight sulfuric acid (wt/wt) with 60-90 g/l Copper sulfate pentahydrate. These baths have very good throwing power. PC boards need this to throw into the small holes. This type of bath doesn’t “level” well, meaning it won’t build additional brightness over scratched or uneven surfaces. A decorative bath is formulated using about 4% (v/v) sulfuric and ~200-240 g/l Copper sulfate pentahydrate or 27-32 oz/gal. These baths, with the proper brightener systems, are excellent at leveling and building brightness and are used for electroforming applications. You’ll also need about 0.5-0.7 ml/gallon of a standard 37% wt/wt hydrochloric acid. I hope this helps you some. Note: Been in the EP business ~48 years. More on reddit.com

If you are doing metal transfer electrolysis - using a copper anode with a copper sulfate electrolyte to transfer copper to the cathode - then all you need is copper sulfate. Adding sulfuric acid is not necessary. For this method, your anode has to be a piece of copper metal. But the cathode can be any other metal object you may want to plate with copper. This is the cleanest way of doing copper electroplating, because the composition of the electrolyte doesn't change at all. Copper metal is oxidized to Cu2+ ions at the anode - these travel through the solution and get reduced back to copper metal at the cathode. The copper sulfate solution acts as a transfer medium and is not consumed, so you can re-use it as many times as you like. This is exactly the same process as is used for the electrolytic refining of crude copper to make high purity, electronics grade copper. In such refineries, the crude, impure copper is the anode in a copper sulfate solution. The cathode is a thin sheet of pure copper. The direct current simply transfers copper from the anode to the cathode. Impurities fall off the anode to the bottom of the container. These are usually collected since they often contain silver and other valuable metals. If the cathode metal is more electropositive (more reactive) than copper, such as iron or zinc, make sure you dip the copper anode into the electrolyte first, then apply the voltage, then lower the cathode piece into the electrolyte. This is because if a more reactive metal than copper is exposed to a copper sulfate solution without it being the negative electrode, a redox reaction will happen: The more electropositive metal will be oxidized and go into solution as its ions, causing copper ions from the solution to be reduced and precipitate out as copper metal. This partially depletes your electrolyte while simultaneously contaminating it with other metal ions. However, metal transfer electrolysis is not the only possible method. You can use your copper sulfate solution as the source of the copper metal for electroplating. This also doesn't require acid. The metal object to be plated with copper still needs to be the cathode - Cu2+ ions will be reduced to copper metal here in the same way as before. But sulfate ions are unreactive to electrolysis, so these are not consumed. Instead, water molecules are oxidized to produce oxygen gas at the anode, leaving H+ ions (ok, technically H*3*O+ ions in reality) behind in solution. Which means that you will generate dilute sulfuric acid anyway as the Cu2+ ions are consumed. So for this method, it is best if your anode is non-reactive towards acids, such as graphite or platinum. If you did use another metal for the anode which could react with sulfuric acid, it would dissolve as the acid level increased, contaminating your electrolyte. More on reddit.com