Easy way to balance this equation?

[mashimlro]

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Balance the equation: KMnO4 + NH3 → KNO3 + MnO2 +KOH + H2O

how can I balance it w/i 0.9 minutes?

 

[FataL]

Edited....didnt see the h20 at the end

 

[Shinpe]

Balance the equation: KMnO4 + NH3 → KNO3 + MnO2 +KOH + H2O

how can I balance it w/i 0.9 minutes?

Ok let's see if I can do this:

a*KMnO4 + b*NH3 → c*KNO3 + d*MnO2 + e*KOH + f*H2O

We must have:
a=d (from Mn)
a=c+e (from K)
3b=e+2f (from H)
4a=3c+2d+1e+1f (from O)
b=c (from N)

(6 unkowns 5 equations, u gonna have to chose one at random)
thus

(from H): f=1/2(3c-e)
(from O equation): 4(c+e)=4c+4e=3c+2d+1e+1f=3c+2(c+e)+1e+1/2(3c-e)
4c+4e=3c+2c+2e+1e+3/2c-1/2e

4c+4e=6.5c+2.5e => 2.5c=1.5e or 5c=3e

Now chose one of them as you'd like:
Im gonna set e=5, then c=3=b, a=8=d, f=2

Let's check it
8*KMnO4 + 3*NH3 → 3*KNO3 + 8*MnO2 + 5*KOH + 2*H2O

Yup it works.

Can you do it under 0.9 minutes??? Depends on your math skills, probably not, I couldn't lol

Usually half reactions work fastest but I couldnt break this up into a half reaction because of the da** Ks lol
I'm sure someone else can do it faster. I just like math ;p

 

[mashimlro]

8*KMnO4 + 3*NH3 → 3*KNO3 + 8*MnO2 + 5*KOH + 2*H2O

😀 Yes! ur right-

Thank you for sharing ya's great method!

 

[miedvied]

Wow, Shin. I've never seen that approach before. Looks awesome for teaching people who can't pick up the "intuitive" way of doing stoichio, and probably more resistant to cases of nerves - but man, that's slow!

 

[TerpDentist]

Don't forget the working backwards method either. It might take you slightly more than a minute but you can look at the answers and see which one works/doesn't work.

 

[Shinpe]

Wow, Shin. I've never seen that approach before. Looks awesome for teaching people who can't pick up the "intuitive" way of doing stoichio, and probably more resistant to cases of nerves - but man, that's slow!

I never use it myself, unless all the easy approaches fail. Math never fails me ;p