We here in CHina learn chemistry, physics, mathematics in Chinese. Honestly now they have translated some into English. But it is still badly insufficient.
Here I open this section and hope to learn more.
FIRST:
heated(can I say the process in this way?)
2KMnO2===============================k2MnO4+MnO2+O2
You can write KMnO2 + heat ->, or a common shorter way is to write a small triangle above the arrow to indicate that heat is required. A reaction that requires a net heat input is "endothermic"--I think that's the English word you're looking for with the reaction above.
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ebrown p
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Thu 17 Mar, 2005 12:10 pm
Are you looking for the term "decomposition"?
Decomposition signifies a type of reaction where a chemical breaks up into smaller parts. For example, H2O decomposes into 2H2 and O2 in the right conditions.
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lab rat
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Thu 17 Mar, 2005 02:53 pm
Your reaction could also be labelled a redox reaction (OXidation-REDuction). Technically, you should probably include O2 as a reactant. The balanced equation would be
2KMnO2 + 2 O2 --> K2MnO4 + MnO2 + O2
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J-B
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Fri 18 Mar, 2005 04:55 am
Yes! decomposition.
And "endothermic" and "redox" are great too
THanks for the detailed help.
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J-B
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Fri 18 Mar, 2005 05:03 am
QUESTION:
We name the group which "CuO" is in "compound", then what do you call the group which "O2" is in?
Thanks
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lab rat
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Fri 18 Mar, 2005 12:48 pm
O2 is a diatomic molecule. It is also an element.
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J-B
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Sat 19 Mar, 2005 12:08 am
Ok..maybe I have made a misunderstanding.
I mean what "O2", "H2", "Fe", are? By contrast with compound such as "CuO", "H2O", "Fe2O3" etc.
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J-B
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Sat 19 Mar, 2005 07:46 pm
anyone help?
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lab rat
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Mon 21 Mar, 2005 09:02 am
Fe, C, S, etc.--anything directly off the periodic table--are elements.
O2 and H2 (likewise N2) are also elements, but their natural state is as diatomic molecules--one would not write the element oxygen as "O", because it occurs as "O2". I wasn't sure from your initial question if you were looking for the word "element" or the description "diatomic molecule".
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J-B
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Tue 22 Mar, 2005 05:22 am
No, sorry neither of them.
What I asked was a substance of which the molecules are merely consisting of 1 type of element(s).
Like, Fe, O2, O3, C, H2....
They are the contrast with the compounds such as CO2, Fe2O3, Cuo, H2O, NaCl.....
Is that clear now?
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farmerman
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Tue 22 Mar, 2005 06:31 am
When an element can naturally occur alone, we (geochemists) call them "NATIVE"as far as gases they are usAULLY diAtOMIC AND THE FIRST BUNCH OF COMPOUNDS are all OXIDES.
The permanganate reaction up front was best decribed as redox as labrat said. We usually do that reaction as an action On some other compound that is oxidized also, then one of the reactants is oxidized and the other is reduced.
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J-B
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Wed 23 Mar, 2005 04:44 am
That is inspiring
THanks for you all
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J-B
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Wed 23 Mar, 2005 04:46 am
Another one:
Quote:
pH
I know what is that used for, I just cannot understand what does it stand for.
THanks
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lab rat
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Wed 23 Mar, 2005 08:48 am
The "p" is just shorthand that indicates the negative base 10 log (-log). For example, pH = -log [H+], pKa = -log Ka (the rate constant for acid dissociation), etc.
[H+] is also occasionally written as [H3O+] and is a generic representation of "acid concentration". This is a somewhat simplified approach; e.g., some acidic compounds are electron acceptors, not H+ donors, so the pH or "acid concentration" in such cases does not necessarily arise from species such as "H+" or "H3O+" in solution.
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J-B
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Fri 25 Mar, 2005 03:08 am
Quote:
acid electron acceptors, not H+ donors,
for example?
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bandido
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Fri 25 Mar, 2005 02:44 pm
Hi JB
The reaction, as given, is incorrect, but I assume the type of reaction you are trying to show is called "Disproportionation". Here, the reactant undergoes both oxidation and reduction.
Regards
bandido
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J-B
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Fri 25 Mar, 2005 09:49 pm
bandido wrote:
Hi JB
The reaction, as given, is incorrect, but I assume the type of reaction you are trying to show is called "Disproportionation". Here, the reactant undergoes both oxidation and reduction.
Regards
bandido
Thanks Bandido Welcome to A2K
But what is incorrect?
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J-B
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Mon 28 Mar, 2005 03:35 am
Ok, new question comes up:
Liquefaction: from gas to liquid
Melt: from solid to liquid
From gas to solid?
From solid to gas?
From liquid to gas?
From liquid to solid?
Thanks.
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lab rat
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Mon 28 Mar, 2005 07:26 am
Alumina and diborane (B2H6) are both examples of "Lewis acids"--i.e., their acidity is defined as the ability to accept electrons from Lewis bases (electron donors).
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