Alternative to Guess and Check?

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Alternative to Guess and Check?

Postby MKearney_4G » Sun Oct 06, 2019 5:14 pm

In my discussion section we had a balancing problem:

S + HNO3 <=> H2SO4 + NO2 + H2O

While I now understand how to do this particular problem (1,6,1,6,2), it took me a LONG time I am not confident I could do this on a test.

Is there an alternative, more procedural/mathematical way to balance chemical reactions? Everybody that I've asked has basically told me to just guess and check and that that is the best way.

Cassidy Kohlenberger 3D
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Re: Alternative to Guess and Check?

Postby Cassidy Kohlenberger 3D » Sun Oct 06, 2019 5:25 pm

I'd recommend balancing the simplest formula/element last. Most of the time this is hydrogen or oxygen. Also, writing how many moles of each element you have on both the reactant and product side can keep you organized when balancing the equation. There isn't a definitive way to balance equations, but there are strategies that you can implement to make it easier. Check out this link ... ons-603860 for more help :)

Lauren Bui 1E
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Re: Alternative to Guess and Check?

Postby Lauren Bui 1E » Sun Oct 06, 2019 5:26 pm

I usually begin to balance an equation by starting from the left side of the reactants side. So I first would balance sulfur, then hydrogen, etc. In this case, sulfur would be balanced, but by adjusting the hydrogen levels, you would have to go back and adjust the level of sulfur. This method still requires guessing and checking, but I find it to be more methodical and less time consuming. I do not think there is any formula or secret short cut to balance equations.

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Re: Alternative to Guess and Check?

Postby Chem_Mod » Sun Oct 06, 2019 5:32 pm

Yes there is an effective way. Balance the simplest species first and then move on to the harder ones. By simplest, I mean which appears the least amount of times on each side of an equation. Take this typical combustion reaction-which you should know the reactants and products of.

CH4 + O2 ==> CO2 + H2O

The "simple" ones here are either C or H, because as you can see they only appear in one molecule on each side of the equation. O should be balanced last because it is the most complex, as you can see it appears once on the left side, but twice on the right side, in both CO2 and H2O.

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Re: Alternative to Guess and Check?

Postby 305376058 » Sun Oct 06, 2019 8:16 pm

I usually find that starting with the element that occurs the least on both sides works best. For example, if carbon was only in one place on both sides, I would start with that. This helps prevent some of the guessing and checking as you can usually build up to some of the reoccurring elements.

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Re: Alternative to Guess and Check?

Postby gabbymaraziti » Sun Oct 06, 2019 9:28 pm

I usually start balancing equations with the element that occurs alone on either side of the equation. In this example's case, it would be Sulfur. By balancing the isolated element, you can then focus on the more complicated elements and mixed compounds. It usually does include some guessing and checking though... I don't think there is a method that avoids it.

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