Mixell
Hazard to Others
Posts: 449
Registered: 27-12-2010
Member Is Offline
Mood: No Mood
|
|
Hydrogen peroxide and various substances.
Hello everybody, I need help completing the following equations and a bit more:
The hydrogen peroxide in use was 33%.
CuSO4 + H2O2(aq)---> ?
The solution acquired a dirty green color upon reaction.
2Al(s) + 6NaOH---> 2Na3AlO3(aq) + 3H2(g).
Upon dissolving aluminium (aluminium foil was used) in a ~30% solution of sodium hydroxide(might have been more or less, not quite sure) a black
solution (much like oil) was formed (I assume the Na3AlO3 should be colorless).
So can anyone fix my equation or tell me what precipitants could have caused the black color in the solution?
Also, will the anion AlO3 (3-, if its an anion at all) form insoluble materials with cations like Cu (2+), Fe (3+),Mn (2+/4+) and Al (3+).
Also, how potassium permanganate (both in solid and in aquatic solution) will react with sulfuric (97%) and nitric acid (68%).
And finally, will hydrogen peroxide react with various acids (HCl,H2SO4,HNO3)?
Thanks in advance for everybody who can help answer my questions =)
|
|
|
blogfast25
International Hazard
Posts: 10562
Registered: 3-2-2008
Location: Neverland
Member Is Offline
Mood: No Mood
|
|
Cu + H2O2 doesn’t really go anywhere without a strong acid like HCl present. In those conditions it will slowly dissolve to CuCl2…
For aluminium + NaOH the reaction is actually:
NaOH + Al + 3 H2O === > NaAl(OH)4 + 3/2 H2
Your foil probably contains small amounts of C and Si which won’t dissolve so easily, especially if your NaOH was depleted by reaction with the Al.
Try gentle and prolonged heating, followed by filtering. NaAl(OH)4 (sodium aluminate) is well soluble in water. Your solution appears oily because
it’s quite concentrated. The cations you mention would drop out as hydroxides, with the possible exception of Cu(OH)2 which is slightly amphoteric.
DO NOT MIX potassium permanganate with concentrated mineral acids, the highly explosive Mn2O7 will form!
And as you are clearly a beginner, don’t mix strong oxidisers like H2O2 with HNO3 unless YOU KNOW WHAT YOU’RE DOING!!!
[Edited on 27-12-2010 by blogfast25]
|
|
|
Mixell
Hazard to Others
Posts: 449
Registered: 27-12-2010
Member Is Offline
Mood: No Mood
|
|
Thank you for the response, but i found the following reaction on the internet:
2Al + 2NaOH + 2H2O → 2NaAlO2 + 3H2
who's products are different then yours.
|
|
|
woelen
Super Administrator
Posts: 7987
Registered: 20-8-2005
Location: Netherlands
Member Is Offline
Mood: interested
|
|
Mixell, your reaction is the same as blogfast25's. You see, in your reaction you get the same amount of hydrogen as in blogfast25's reaction for the
same amount of aluminium and the same amount of NaOH is used. The only difference is the amount of water taken up.
The compound NaAl(OH)4 can be written as NaAlO2.2H2O. The real compound probably is none of these exactly, it can best be described as NaAlO2.xH2O,
with x some indefinite value.
|
|
|
blogfast25
International Hazard
Posts: 10562
Registered: 3-2-2008
Location: Neverland
Member Is Offline
Mood: No Mood
|
|
Quote: Originally posted by woelen  | Mixell, your reaction is the same as blogfast25's. You see, in your reaction you get the same amount of hydrogen as in blogfast25's reaction for the
same amount of aluminium and the same amount of NaOH is used. The only difference is the amount of water taken up.
The compound NaAl(OH)4 can be written as NaAlO2.2H2O. The real compound probably is none of these exactly, it can best be described as NaAlO2.xH2O,
with x some indefinite value. |
Hmmm.... from what I've read about the aluminate anion, it really has to considered a coordination complex: [Al(OH)4(H2O)2]-. Six ligands...
Most modern descriptions of aluminium's hydrolysis are formulated in those tems:
[Al(H2O)6]3+ in acid conditions
[Al(OH)n(H2O)6-n]3-n in intermediate conditions
[Al(OH)3.3H2O] in near neutral conditions
[Al(OH)4(H2O)2]- in alkaline conditions
The Al3+ ion has the right size and central coloumbic attraction for that. See also the AlF6(3-) anion from cryolite...
[Edited on 27-12-2010 by blogfast25]
|
|
|
Mixell
Hazard to Others
Posts: 449
Registered: 27-12-2010
Member Is Offline
Mood: No Mood
|
|
Update:
The black solution dispersed to two substances: a gray floating solid that later was dumped to the drain with the solution itself.
And an oily very dark substance that sank to the bottom of the glass, the oily substance had no solids inside of it, but after a few days (and an
addition of water) the substance turned into a dirty looking gray-white solid (that contains no solid aluminium).
Any guess what that thing could be?
[Edited on 30-12-2010 by Mixell]
|
|
|
Random
International Hazard
Posts: 1018
Registered: 7-5-2010
Location: In ur closet
Member Is Offline
Mood: Energetic
|
|
gray white solid could be aluminium hydroxide
|
|
|
Mixell
Hazard to Others
Posts: 449
Registered: 27-12-2010
Member Is Offline
Mood: No Mood
|
|
How can I test it to be sure?
|
|
|
Mixell
Hazard to Others
Posts: 449
Registered: 27-12-2010
Member Is Offline
Mood: No Mood
|
|
It doesn't react with NaOH, so it can't be Al(OH)3.
[Edited on 30-12-2010 by Mixell]
[Edited on 30-12-2010 by Mixell]
|
|
|
![[*]](images/xpblue/default_icon.gif){kind=icon}
