Matalic powder ??

[person]

I was walking ... ok you dont need to know the details.

 

I have a jar of metalic powder that i found in a garage. It was used to make reflective paint so i asumed Al ... So to test my theory i put a pinch into HCl but nothing happened so now i am lead to believe that it is not Al. I tested it with a magnet. Its not magnetic. It is grey in colour and is quite heavy (i will work out its density and post it later)

 

Any suggestions as to how i can find out what it is ???

Much appreciated

[hermanntrude]

flame test?

[person]

Mmm good idea ...

 

I could not perform the flame test (out of gas).

 

I did another test with HCl , using less diluted acid (30%). It reacted slowly and the acid/powder mix is now a dark green colour.

[YT2095]

I`st of all you don`t mention what color the powder is, is there a reason for that?

 

a green soln does however narrow it down somewhat, now try using sodium hydroxide

Edited November 18, 2008 by YT2095
multiple post merged

[person]

It is a grey/silver metalic powder.

I didnt observe any reaction between it and a strong NaOH soln after 20 min.

It has a density of 3.08 g/ml

 

Something to consider, it might be an aloy.

 

P.s my density might be slightly off (i used a scale that only has one decimal).

thnx

[hermanntrude]

i suspect your density is wonky. A powder isn't the same volume as a solid. Also your powder might not be entirely dry or free of oxides and other contaminants

[DrP]

So what colour flame does it give in a bunsen then?

[person]

I couldnt perform a flame test because i dont have gas for my bunsen burner!!

[YT2095]

if it didn`t react with the NaOH then it`s not Alu, another idea would be to crystalise your green soln and look at them under the microscope, their shape and color can be very revealing.

[person]

I dont have a microscope lying around and its going to take me a day or so to crystalise the green stuff so il keep you posteed.

[hermanntrude]

I couldnt perform a flame test because i dont have gas for my bunsen burner!!

 

a candle or any other flame should work too

[Flashman]

My best guess right now is chromium powder, in which case when you crystalise the green stuff then dehydrate it, it should turn purple.

[person]

I did what the flashman said and it turned light green/yellow then upon more heat went brown and then black??

[Flashman]

Odd, that sounds more like nickel but that should have been magnetic as the powder.

[YT2095]

sounds like Copper to me, perhaps a Brass, especially the chlorides then oxides.

perhaps it`s been coated with something?

 

try dissolving in Nitric acid, and then add a a weak chloride soln to this, look for a white PPT, I`v seen Silver (alloyed with copper) have this effect.

did all the powder dissolve when you did the HCl addition?

[person]

No not all the powder disolved (it could just be that the acid lost some acidity though)! I gree that it may be a aloy of copper but i dought it contains any silver (baught it for quite cheep).

 

It was slightly affected by a strong magnet (when i moved the magnet close i saw the particles moving a bit) but not enough for the powder to "slick" to the magnet.

 

What chloride soln should i add to the nitric HNO3 metal mix (chloride that i got from the HCl and metal mix)?

 

Thanx

[YT2095]

a simple salt water soln would provide the chloride needed.

if it goes cloudy white, then it likely contains silver.

[person]

Thanx to all but im not gonna go further with this seach. What ever it is it doesnt seem to be very usefull to me and i dont have time to deal with it now, so thanx for all the help.

[tomgwyther]

Titanium Dioxide, calcium carbonate Are used in commercial reflective paints according to their MSDS sheets.

[DrP]

Titanium Dioxide, calcium carbonate Are used in commercial reflective paints according to their MSDS sheets.

 

Yea - TiO2 as a white pigment and CaCO3 as a filler. The reflectivity would come from metalic particulates.