aj47 Posted February 12, 2006 Share Posted February 12, 2006 A few days ago when I was rummaging around under my bed, I found a jar of metallic powder from my old art set. I have often heard that aluminium powder can be used in mixing paints etc so i'm wondering whether what I have is aluminium. Can any of you think of any simple chemical test I can carry out to determine whether it is in fact aluminium? Link to comment Share on other sites More sharing options...
vrus Posted February 12, 2006 Share Posted February 12, 2006 Well, there are quite somethings you can do to find out the 'true identity' of this substance! (i) If you wanna have some fun and take a bit of risk, then put some of the powder in Mercury Chloride and filter; it should start reacting exothermically with the O2 in the air, as the Mercury Chloride removes Al's oxide layer. I doubt you have this and should take the risk, but just 4 some info (ii) You could mess around with displacement reactions and the sort. Getting an aqueous Mg salt and adding the Al powder to it and doing the same to Zn, Fe, etc (metals lower than Al in reactivity series). It should not displace mg and above, but should displace all those below itself. You know that displacement has occurred when there is a change in colour of the solution or temperature changes. (iii) Probably the easiest would be to use QUALITATIVE ANALYSIS. Make a salt of a sample of the suspected powder. Then do the following :- Add the aqueous Aluminium salt to an equal amount of aqueous NaOH. A white ppt. should form. An excess of the same will have no effect. You should also obtain the same results with Ammonia solution. This should prove it is Aluminium. If anybody has any more ideas ideas, please go ahead.. I'm quite interested myself! Link to comment Share on other sites More sharing options...
aj47 Posted February 12, 2006 Author Share Posted February 12, 2006 good ideas but I don't really have any access to those kind of reagents. Link to comment Share on other sites More sharing options...
aj47 Posted February 12, 2006 Author Share Posted February 12, 2006 Just burnt a small amount and it sparkled like magneisum powder, hmmm Link to comment Share on other sites More sharing options...
woelen Posted February 12, 2006 Share Posted February 12, 2006 Get some hydrochloric acid (around 30% HCl) from a hardware store and do the following: Dilute the acid to 10% HCl by mixing two parts of water with one part of acid. Add a spatula full of powder to the acid. If it reacts immediately and violently, then most likely it is magnesium or a magnesium-rich alloy (magnalium). If it does not react immediately, but it takes some time, then it may be aluminium. A confirmative test may be to add a spatula of the powder to concentrated 30% HCl. With this it should give a violent reaction, with an induction period of a few seconds. If the powder does not react with concentrated HCl or only very slowly, then it definitely is not aluminium powder. If the solution is not colorless after the powder is dissolved, then another metal may be present as well. Some paint-store aluminium powders contain some copper. A solution of aluminium (and also of magnesium) in hydrochloric acid is colorless. The tests I present here of course are not 100% fool-proof, but with the materials, available for the general public it is the best there is. Given the small number of possibilities for the powder, I also think that this is a fairly complete test in the case of quick dissolving. I do not expect you to have powdered beryllium metal or a powdered lanthanoid around . Link to comment Share on other sites More sharing options...
aj47 Posted February 12, 2006 Author Share Posted February 12, 2006 aha good idea thanks Link to comment Share on other sites More sharing options...
aj47 Posted February 12, 2006 Author Share Posted February 12, 2006 Actually thinking about it I probably have a small amount of KNO3 somewhere, do you think the aluminium would react in the same way magneisum does in KNO3:Mg flash powder? Link to comment Share on other sites More sharing options...
woelen Posted February 13, 2006 Share Posted February 13, 2006 I expect it to react nicely. Adding a small amount of sulphur makes ignition easier though. Link to comment Share on other sites More sharing options...
vrus Posted February 14, 2006 Share Posted February 14, 2006 So you mean a thermite reaction Woelen ? Link to comment Share on other sites More sharing options...
YT2095 Posted February 14, 2006 Share Posted February 14, 2006 after the HCl test perform a NaOH test (sodium hydroxide) if it`s alu it will react there also. I gather you`ve already tried a simple Magnet test? Link to comment Share on other sites More sharing options...
woelen Posted February 14, 2006 Share Posted February 14, 2006 So you mean a thermite reaction Woelen ? No, I do not mean a thermite reaction. The OP asks about KNO3:Al mix or KNO3:Mg mix. Many mixes are somewhat hard to ignite and sometimes also have some difficulty to keep them going. If you mix some sulphur with a composition, then it makes ignition much easier. That is why BP has some sulphur in it. A plain KNO3:C mix is quite hard to ignite, with a few percents of sulphur it can be ignited easily with a spark or a simple flame. Link to comment Share on other sites More sharing options...
rthmjohn Posted February 23, 2006 Share Posted February 23, 2006 Three things: 1. Aluminum powder ranges from bright silver to dark grey depending on the mesh, but the overall color shade is grey. 2. The sodium hydroxide test is probably the easiest way. Just get some lye from your local hardware store and then make a dilute solution of it. Drop a dash of the powder you have in the solution. If you notice an immediate and rapid reaction, then you most likely have aluminum. 3. Also, Al doesn't burn unless strongly heated. Think Mg burns easier, but I could be wrong. Link to comment Share on other sites More sharing options...
John Cuthber Posted February 26, 2006 Share Posted February 26, 2006 There are only 2 common metals that disolve in NaOH solution ; Zn and Al. Zn doesn't work nearly as well. The solution of aluminate or zincate will give a ppt of the hydroxide if you neutralise it with acetic acid. Zinc hydroxide will dissolve in ammonia solution. Link to comment Share on other sites More sharing options...
aj47 Posted February 26, 2006 Author Share Posted February 26, 2006 mixed the powder in 1:3 ratio with KNO3 and got very violent reaction, so i'm almost certain its aluminium now. Link to comment Share on other sites More sharing options...
[w00t] Posted February 28, 2006 Share Posted February 28, 2006 Actually thinking about it I probably have a small amount of KNO3 somewhere, do you think the aluminium would react in the same way magneisum does in KNO3:Mg flash powder? err KNO3:AL doesnt ignite(without sulfur).. and if it did u proablly need 600+ mesh flake AL.. my 400mesh with kno3 dont do anything cant even start it with a sparkler which i use to initiate thermite Link to comment Share on other sites More sharing options...
aj47 Posted February 28, 2006 Author Share Posted February 28, 2006 '']err KNO3:AL doesnt ignite(without sulfur).. and if it did u proablly need 600+ mesh flake AL.. my 400mesh with kno3 dont do anything cant even start it with a sparkler which i use to initiate thermite I managed to light mine with magnesium ribbon and it was fine. Link to comment Share on other sites More sharing options...
TATER Posted February 2, 2007 Share Posted February 2, 2007 If you want to have a little pyro fun then (if you have any) add 40% potassium perchlorate and you will create flash powder (if it is Al powder) Link to comment Share on other sites More sharing options...
aj47 Posted February 2, 2007 Author Share Posted February 2, 2007 It will be closer to 70% perchlorate. I'm a bit bored of flash anyway. Link to comment Share on other sites More sharing options...
jdurg Posted February 3, 2007 Share Posted February 3, 2007 You could also add a tiny, and I mean TINY, bit of iodine crystals to the powder and add a tiny drop of water. If aluminum, it will violently react. If another powdered metal, there would be little reaction if any. Link to comment Share on other sites More sharing options...
TATER Posted February 6, 2007 Share Posted February 6, 2007 what mix ratio would that be? Link to comment Share on other sites More sharing options...
jdurg Posted February 7, 2007 Share Posted February 7, 2007 A fingernail's size pile of aluminum powder to one small crystal of iodine and one drop of water. The reaction is near instantaneous. Link to comment Share on other sites More sharing options...
FriedChicken Posted February 15, 2007 Share Posted February 15, 2007 Try lighting a small pile on the ground w/a magnesium ribbon. If it burns like the magnesium ribbon, it's magnesium. If it's aluminum, it probably won't burn. Link to comment Share on other sites More sharing options...
TATER Posted February 28, 2007 Share Posted February 28, 2007 I tried doing that experiment the other day and nothing happened. i know that the iodine is pure but i'm not so sure w/ the Al powder. Link to comment Share on other sites More sharing options...
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