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Chemistry Forums for Students => High School Chemistry Forum => Topic started by: hullio on March 26, 2007, 07:06:15 PM

Title: Hard Balancing Equation! Please *delete me*
Post by: hullio 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

Please *delete me* Thanks.

Title: Re: Hard Balancing Equation! Please *delete me*
Post by: millerst 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

Title: Re: Hard Balancing Equation! Please *delete me*
Post by: hullio 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! ;)

Title: Re: Hard Balancing Equation! Please *delete me*
Post by: hullio 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?

Title: Re: Hard Balancing Equation! Please *delete me*
Post by: millerst on March 26, 2007, 08:19:25 PM

One of your compounds is H20 (20 atoms of H). Did you mean H2O (water)?

Title: Re: Hard Balancing Equation! Please *delete me*
Post by: hullio on March 26, 2007, 08:31:30 PM

Yes sorry.

Title: Re: Hard Balancing Equation! Please *delete me*
Post by: millerst on March 26, 2007, 08:35:22 PM

4 Zn + 5 H2SO4 ---> 4 ZnSO4 + 4 H2O + H2S

Title: Re: Hard Balancing Equation! Please *delete me*
Post by: hullio 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                         

Title: Re: Hard Balancing Equation! Please *delete me*
Post by: constant thinker 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.

Title: Re: Hard Balancing Equation! Please *delete me*
Post by: AWK on March 27, 2007, 02:04:15 AM

Quote from: hullio 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?

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

Title: Re: Hard Balancing Equation! Please *delete me*
Post by: Borek on March 27, 2007, 02:56:18 AM

how to balance chemical reaction equations (http://www.chembuddy.com/?left=balancing-stoichiometry&right=toc)

Title: Re: Hard Balancing Equation! Please *delete me*
Post by: bigblue17 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)

Title: Re: Hard Balancing Equation! Please *delete me*
Post by: Borek on April 08, 2007, 03:27:04 AM

Quote from: bigblue17 on April 07, 2007, 08:32:03 PM

either KCO3 or KCO4 i forget

Neither. K₂CO₃. 24N₂.

Check out this page for a list of reactions to balance:

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

Scroll down for really hard ones.

Title: Re: Hard Balancing Equation! Please *delete me*
Post by: phoebusvn on April 14, 2007, 11:06:52 PM

Quote from: Borek on April 08, 2007, 03:27:04 AM

Quote from: bigblue17 on April 07, 2007, 08:32:03 PM

either KCO3 or KCO4 i forget

Neither. K₂CO₃. 24N₂.

Check out this page for a list of reactions to balance:

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

Scroll down for really hard ones.

Thanks for the website. it is good for practicing.