guy - 14-4-2004 at 22:58
What does Calcium hydroxide and H2O2 make? I've done it and lots of bubbles form, and the calcium turns yellow. What is the "yellow
calcium"?
Pyrovus - 15-4-2004 at 01:26
H2O2 is quite unstable in alkaline solution, so your bubbles come from the reaction 2H2O2 -> H2O +O2. I'm not too sure about the yellow colour
though - how pure is your calcium hydroxide?
guy - 15-4-2004 at 10:31
It should be 99-100% pure
The_Davster - 15-4-2004 at 13:08
I seem to remember reading a patent a while ago which involved adding H2O2 to a zinc hydroxide solution in ammonia to yield zinc peroxide. This could
have been what happened to you, except the calcium analog. You may have made calcium peroxide
. I'm not 100% sure on this though.
blip - 15-4-2004 at 15:12
Undoubtedly much of your H<sub>2</sub>O<sub>2</sub> decomposed, but some may have formed CaO<sub>2</sub> due to
its relative insolubility (said to be insoluble in the reference doc). It is described as being "White or yellowish powder". If you did
this in a covered container so that dust could not enter and the container couldn't somehow break down in any way like a cheap cup might, then
some possibilities are eliminated. I once tried this, but I was unable to continue when the froth began pouring out of the container and I had to
dump it out in the sink. 
http://www.chem-world.com/pdf/calcium-peroxide-msds.pdf
The_Davster - 15-4-2004 at 20:12
I tried this reaction with sodium hydroxide and hydrogen peroxide. I got some bubbling, the beaker heated up a bit, I left it for a while and now, I
have a crystaline precipitate. Could this be sodium peroxide. I sort of doubt
that it is because I remember reading that sodium peroxide reacts with water to give concentrated H2O2, so I probally just have some sodium hydroxide
that re-crystallized that was only soluble when the beaker heated up.