Manganese + Hydrogen

[Aka]

when you mix Manganese (s) with Hydrogen (L) the manganese remains at the bottom of the test tube, why is that? Is it because the hydrogen solution is fully saturated?

[RyanJ]

when you mix Manganese (s) with Hydrogen (L) the manganese remains at the bottom of the test tube, why is that? Is it because the hydrogen solution is fully saturated?

 

I am confused - is the hydrogen an aqueous solution, part of an acid...?

 

The L there states its in its liquid state so I really don't understand.

 

Cheers,

 

Ryan Jones

[woelen]

Hydrogen is a gas at room temperature and I do not believe that you have access to liquid H2. That would require temps of -260 C or something like that.

 

Anyways, manganese is a metal and is fairly dense, so it simply sinks to the bottom in aqueous solutions. It, however, dissolves fairly easily in acidic solutions, and then gives hydrogen gas, itself being converted to the (almost) colorless manganese (II) ions.

[Aka]

^ Sorry

 

Hydrogen Peroxide

[RyanJ]

^ Sorry

 

Hydrogen Peroxide

 

Umm would'nt Manganese simply catalyse the decomposition of the hydrogen peroxide?

 

Cheers,

 

Ryan Jones

[Darkblade48]

You might be thinking of manganese dioxide.

 

Though manganese ions may catalyze the decomposition of the hydrogen peroxide somewhat.

[RyanJ]

You might be thinking of manganese dioxide.

 

Though manganese ions may catalyze the decomposition of the hydrogen peroxide somewhat.

 

Just about everything catalyses hydrogen peroxide, silver does and iron does too... never actually tried it with Mn so I don't really know but I'm guessing it would...

 

Cheers,

 

Ryan Jones

[woelen]

Some of the Mn will be oxidized by the H2O2 to MnO2 and this MnO2 will catalyse decomposition of H2O2 much more than plain Mn. Indeed, many things catalyse decomposition of H2O2, but MnO2 is particularly powerful in this catalysis.

[Aka]

You might be thinking of manganese dioxide.

 

ur right its manganese dioxide

 

I feel really stupid but i don't understand what u guys r saying...the manganese dioxide would decompose the Hydrogen Peroxide instead of the other way around...it that why there was still some on the bottom of the test tube?

[RyanJ]

ur right its manganese dioxide

 

I feel really stupid but i don't understand what u guys r saying...the manganese dioxide would decompose the Hydrogen Peroxide instead of the other way around...it that why there was still some on the bottom of the test tube?

 

Well yes it does decompose it:

 

[ce]2H2O2 ->[MnO_2] 2H2O + O2[/ce]

 

So the only reason there should be some left is that all the hydrogen peroxide has been deduced and so there is excess manganese dioxide.

 

This may prove interesting for you. Not quite the same but its an interesting video

 

Cheers,

 

Ryan Jones

[woelen]

Manganese peroxide is a catalyst for decomposition of H2O2. It is not used up at all in the reaction.

[budullewraagh]

but it really all depends on the reaction conditions. if we have a solid ingot of manganese with minimal surface area and 90% H2O2, the surface of the Mn is oxidized to MnO2, which catalyzes the decomposition of some of the H2O2 before the heat gets so high that the H2O2 decomposes before it can gain access to any sort of catalytic aid