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hullio

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Hard Balancing Equation! Please *delete me*
« on: March 26, 2007, 07:06:15 PM »
Here are two balacing equations which are really hard. I'll be very impressed if someone could balance these! I got these two questions in class and my teacher said that even she couldn't balance (either it can't be possible or she's a total failure).

Cu + HNO3 (concentrated) ----> Cu(NO3)2 + H2O + NO2

and

Cu + HNO3 (dilute) ----> Cu(NO3)2 + H2O + NO

millerst

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Re: Hard Balancing Equation! Please *delete me*
« Reply #1 on: March 26, 2007, 07:14:30 PM »
Here they are, not too hard...

1) Cu + 4 HNO3 ---> Cu(NO3)2 + 2 H2O + 2 NO2

2) 3 Cu + 8 HNO3 ---> 3 Cu(NO3)2 + 4 H2O + 2 NO

hullio

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Re: Hard Balancing Equation! Please *delete me*
« Reply #2 on: March 26, 2007, 07:36:18 PM »
yea they weren't too hard...i think my teacher sucks. i got really stuck on the second one...thank you so much for the quick response!

hullio

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Re: Hard Balancing Equation! Please *delete me*
« Reply #3 on: March 26, 2007, 08:14:34 PM »
I've another one that I'm getting nowhere at...

Zn + H2SO4 ----> ZnSO4 + H2O + H2S

Also, do you guys have any helpful tips to do these balancing equations quicker/more efficiently?
« Last Edit: March 26, 2007, 08:31:56 PM by hullio »

millerst

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Re: Hard Balancing Equation! Please *delete me*
« Reply #4 on: March 26, 2007, 08:19:25 PM »
One of your compounds is H20 (20 atoms of H). Did you mean H2O (water)?

hullio

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Re: Hard Balancing Equation! Please *delete me*
« Reply #5 on: March 26, 2007, 08:31:30 PM »
Yes sorry.

millerst

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Re: Hard Balancing Equation! Please *delete me*
« Reply #6 on: March 26, 2007, 08:35:22 PM »
4 Zn + 5 H2SO4 ---> 4 ZnSO4 + 4 H2O + H2S

hullio

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Re: Hard Balancing Equation! Please *delete me*
« Reply #7 on: March 26, 2007, 08:40:37 PM »
Wow thank you! How do you do them so fast? Care to share any tips? This is how I do them:

Zn + H2SO4 ----> ZnSO4 + H2O + H2S

Zn = 1               Zn = 1
H = 2                  H = 4
S = 1                  S = 2
O = 4                 O = 4

Then I just carry on from there. So how do you do them so fast? I guess you're a number type guy lol

constant thinker

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Re: Hard Balancing Equation! Please *delete me*
« Reply #8 on: March 26, 2007, 09:38:19 PM »
Pay attention to functional groups, like the SO4 (sulfate) group. You can count that as one whole unit sometimes, but in this case it's different. Finding little things like that can help. Practice also helps.
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AWK

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Re: Hard Balancing Equation! Please *delete me*
« Reply #9 on: March 27, 2007, 02:04:15 AM »
I've another one that I'm getting nowhere at...

Zn + H2SO4 ----> ZnSO4 + H2O + H2S

Also, do you guys have any helpful tips to do these balancing equations quicker/more efficiently?
Take this reaction in a few steps
1. Zn + H2SO4 =  ZnSO4 + H2 This is a simple single replacement reaction
Then think how much H2 you need to reduce H2SO4 to H2S and H2O (answer is 4)
Then join this knowledge together
4Zn +4H2SO4 =  4ZnSO4 +4H2
4H2+ H2SO4 = H2S + 4H2O
and finally
4Zn + 5H2SO4 =  4ZnSO4 + H2S + 4H2O
AWK

Borek

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Re: Hard Balancing Equation! Please *delete me*
« Reply #10 on: March 27, 2007, 02:56:18 AM »
ChemBuddy chemical calculators - stoichiometry, pH, concentration, buffer preparation, titrations.info, pH-meter.info

bigblue17

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Re: Hard Balancing Equation! Please *delete me*
« Reply #11 on: April 07, 2007, 08:32:03 PM »
hardest balancing equation i have ever seen is as follows

KNO3 + C12H22O11 -> N2 + CO2 + H2O + potassium carbonate ( either KCO3 or KCO4 i forget)

Borek

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Re: Hard Balancing Equation! Please *delete me*
« Reply #12 on: April 08, 2007, 03:27:04 AM »
either KCO3 or KCO4 i forget

Neither. K2CO3. 24N2.

http://www.chembuddy.com/?left=balancing-stoichiometry-questions&right=balancing-questions

Scroll down for really hard ones.
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phoebusvn

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Re: Hard Balancing Equation! Please *delete me*
« Reply #13 on: April 14, 2007, 11:06:52 PM »
either KCO3 or KCO4 i forget

Neither. K2CO3. 24N2.