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Previous Entry hello! Dec. 30th, 2004 @ 01:03 am Next Entry
When given a problem like Cu + H2O(g)-> how do I solve it? Is there a process to find out what type of reaction it is? I also had the problem of balancing correctly, but the reaction I wrote couldn't happen in real life (e.g.: I thought KClO3-> became 2KClO3->K2+2ClO3, so I got it wrong because i found out that never happens in nature). Which rules would help me avoid that from happening again? even some good links would be greatly appreciated, because I'm so confused! Please help me! :(

Here's some examples from a packet that could be used if needed. the answers are below, but i couldn't understand how to be able to find them on a test:

Write correctly balanced equations for these expressions:
1) KClO3 ->
Ans: 2KClO3 -> 2KCl+3O2

2) KBr + MnO2 + H2SO4 ->
Ans: 2KBr + MnO2 + 2H2SO4 -> 2K^(+1) + Br2 + Mn^(2+) + 2H2O + 2SO4^(2-)

3) AgCl(s) + NH3(aq)
Ans: AgCl(s) + 2NH3(aq) -> Ag(NH3)2^(+1) + Cl^(-1)(aq)

4) Cu + H2O(g)
Ans: Cu + H2O(g) -> Cu^(2+)(aq)
Currently feeling: confusedconfused!!
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From:nabisprinkles
Date:February 9th, 2005 05:32 pm (UTC)

Re: look at the electrons

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This is decomposition of a chlorate.
The general formula for this type of reaction is:
KClO3 --> KCl + O2 (Now balance that and you're good to go, as the person above showed.)

Oh, and Chlorine and Oxygen do form coordinate covalent compounds called oxyanions. [ClO]- is hypochlorite, [ClO2]- is chlorite, [ClO3]- is chlorate, [ClO4]- is perchlorate. The two nonmetals share electrons and the total charge on the oxyanion is 1 minus.

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From:randomisator
Date:March 8th, 2005 01:20 pm (UTC)
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Let's start with 4... If you show me the one who created this test, I might kill him myself:) The reaction is absolutely impossible!
All others you simply have to remember, that's the biggest problem of inorganic chemistry: you have to remember a lot without any explanation. Even if you find some rule, there is an exception. Of course, in tests you are unlikely to find many of them. So here are some rules for you:
1. Every element has preferred oxidation state and usually gets it after the reaction (-1 - for Cl, +2 for Mn)
2. Some elements tend to have that state more, so the could cause others to change their states to less likely (Mn2+ (not 4+ or 7+), Cr3+ (not 6+))
3. Every metal ion always coordinates the same number of ligands (2 - for Ag+)
In fact, to tell all rules I'll have to spend whole hight here, so better simply read books (unfortunatly, I'm russian so I can recommend only russian ones;) )
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