This chemistry experiment reveals you tips on how to produce crimson, orange, inexperienced, yellow, blue and purple multi function resolution, all the colours of the rainbow – with out dyes or indicators. How is that potential? It’s potential utilizing the superb vanadium oxidation states.
We present you tips on how to produce the superb oxidation states of the component vanadium in some of the thrilling experiments now we have ever accomplished. Most variations of this experiment use costly and laborious to seek out reagents like ammonium vanadate or zinc-mercury amalgam, however not us! We present you a neater route. We additionally take you each ahead and again although the assorted oxidation states, and present thrilling middleman colours.
Vanadium compounds are colourful due to the electrons in its d-orbital. The electrons can soak up mild and transfer to a better vitality state, absorbing some colours however reflecting others. All vanadium compounds can soak up some spectra of sunshine, which is why none of them are white.
Vanadium Oxidation States – Supplies:
Vanadium Pentoxide 8.6 grams (OR Sodium vanadate OR Ammonium metavanadate)
Sodium Carbonate 5 grams
Distilled water 500ml
Sulfuric Acid 98% 50 grams
Zinc granules or lumps, or zinc mossy (a small handful)
Potassium permanganate (4 grams in 100ml of distilled water)
Beakers
Flask
Hotplate / Stirrer
Thermometer
The place to get the reagents?
You will have two decisions. You probably have a sizeable price range, you should buy the whole lot you want out of your favourite chemical distributor or retailer. If you happen to don’t, you should buy vanadium pentoxide very cheaply from most pottery provide shops. Within the USA, you may get 93% sulfuric acid from {hardware} shops as drain cleaner. We’ve seen zinc granules and potassium permanganate on the market on-line for as little as $6 USD every.
Chemistry Experiment Instructions:
MAKING SODIUM VANADATE
If you happen to don’t have sodium or ammonium vanadate, you’ll have to make it. Don’t fear, it’s simple to make sodium vanadate. Mix equimolar quantities of vanadium pentoxide and sodium carbonate, combine with water. Use a ratio of 1.72 to 1, for instance 17.2 grams of vanadium pentoxide and 10 grams of sodium carbonate. You possibly can even make your individual sodium carbonate by heating sodium bicarbonate in an over at 450F for an hour (find out how on this video). TIP – vanadium pentoxide prices about 20 instances lower than ammonium metavanadate.
For our process, we used 8.6 grams vanadium pentoxide and 5 grams of sodium carbonate. We used pottery grade vanadium pentoxide and selfmade sodium carbonate, which labored simply superb!
Warmth at 90 levels Celsius utilizing a hotplate stirrer till the answer turns from yellow to inexperienced. It ought to take 5 or 10 minutes. When it turns inexperienced, you may have sodium vanadate!
MAKING VANADYL SULFATE
Add a small quantity of sulfuric acid to your sodium vanadate resolution. We added 50 grams of concentrated sulfuric acid to 500ml of sodium vanadate resolution. When the answer turns yellow, which ought to occur instantly, you now have vanadyl sulfate, which has vanadium within the +5 oxidation state. The vanadyl ion components is VO2+.
MAKING THE COLORS OF VANADIUM
To supply the completely different colours of vanadium compounds, pour the vanadyl sulfate resolution into a big flask, and put it on low warmth on a hotplate / stirrer. And a beneficiant quantity of zinc granules. Because the zinc reduces the vanadium, the colours will change to inexperienced, then blue, then dark-green, and at last purple. It’s important to shake the zinc round within the resolution to get the final 2 colour adjustments. Utilizing a magnetic stirrer will help this course of.
As the colours change, your can pour a few of the resolution out of the flask right into a beaker. Have a number of 100ml beakers lined up, able to go! TIP – Utilizing zinc granules as an alternative of powder means you don’t must filter something, simply pour and the items of zinc stay within the flask. TIP – getting from V+3 to V+2 can take 15 – 40 minutes, utilizing extra zinc, holding it heat, and swirling it round somewhat can preserve the time right down to a minimal. No want for costly and harmful zinc-mercury amalgam!
TIP – the attractive purple colour of the V+2 ion received’t final lengthy in air, because the oxygen will oxidize it again to V+3. Get pleasure from it when you can!
Reversing the vanadium colours, making the rainbow
By including a potassium permanganate resolution, a powerful oxidizing agent, you may reverse the colours. The colours will change from purple, to dark-green, to electrical blue, to yellow. Including extra permanganate at this level will produce orange, after which crimson.
Security Notes for this Experiment:
Vanadium compounds are poisonous, don’t breathe them in, and put on gloves if there’s a hazard of coming into contact with the answer. Sulfuric acid is extremely corrosive – keep away from all contact. Potassium permanganate is a really sturdy oxidizer – by no means combine with fuels or natural compounds. Put on goggles throughout this experiment. Learn our lab security guidelines.
If you are going to buy vanadium pentoxide from a pottery retailer, it’s possible you’ll have to switch it into a correct plastic bottle. We suggest doing this open air whereas carrying gloves and an N95 masks to keep away from respiratory within the mud.
Disposal
Vanadium compounds will be dangerous to marine organisms, don’t wash giant portions down the drain (not more than 1 gram of compound per day), bigger portions needs to be handled as heavy steel waste. You possibly can precipitate vanadium compounds as a hydroxide or sulfide, after which filter and dry the stable compound.
