Tips on what number to multiply the entire equation if needed

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NicoJones_1B
Posts: 49
Joined: Fri Aug 09, 2019 12:16 am

Tips on what number to multiply the entire equation if needed

Postby NicoJones_1B » Tue Oct 01, 2019 12:39 pm

If you don't have a whole number for one of your elements in a reaction after you balance it, what are some tips on which number to use make the equation whole?

Jason Wu 1E
Posts: 101
Joined: Thu Jul 25, 2019 12:15 am

Re: Tips on what number to multiply the entire equation if needed

Postby Jason Wu 1E » Tue Oct 01, 2019 12:46 pm

I believe you could always use whatever number is on the denominator to make the equation whole. For example if one reactant after balancing has 7/4 as its coefficient, you could simply multiply the entire equation by 4 to get everything to a whole number. If there are more than one fraction in the chemical equation, then you could use the multiple of the two denominators or the Least Common Multiple of the denominator.

405335722
Posts: 56
Joined: Fri Aug 30, 2019 12:16 am

Re: Tips on what number to multiply the entire equation if needed

Postby 405335722 » Tue Oct 01, 2019 1:07 pm

It is easiest to write your decimal number as a fraction so you can just divide by the denominator and make every coefficient and integer! I hope this helps.

Zoya Mulji 1K
Posts: 105
Joined: Thu Jul 11, 2019 12:15 am

Re: Tips on what number to multiply the entire equation if needed

Postby Zoya Mulji 1K » Tue Oct 01, 2019 2:21 pm

Given one of the reactants is a hydrocarbon, start by multiplying the hydrocarbon (ex. C4H10) times two and then balancing the other reactants and products according to this. This method isn't necessary, but it prevents you from having to multiply/ deal with fractions at the end of the balancing process.

selatran1h
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Joined: Fri Aug 30, 2019 12:16 am

Re: Tips on what number to multiply the entire equation if needed

Postby selatran1h » Tue Oct 01, 2019 3:34 pm

The objective is to make all of the stoichiometric coefficients into integers. If they are written in fractions, then multiply the entire equation by the least common denominator to both sides.

NRobbins_1K
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Joined: Sat Aug 17, 2019 12:15 am

Re: Tips on what number to multiply the entire equation if needed

Postby NRobbins_1K » Tue Oct 01, 2019 4:23 pm

For simple equations, you will usually only have one number in the denominator of your stoichiometric coefficients. Simply multiply the coefficient of every molecule in the reaction by the number in the denominator to finalize the balanced reaction. If there are multiple numbers in the denominators of your coefficients, multiply by the least common multiple of those numbers to get rid of the denominators and finish balancing the reaction.

Aprice_1J
Posts: 55
Joined: Wed Sep 18, 2019 12:16 am

Re: Tips on what number to multiply the entire equation if needed

Postby Aprice_1J » Tue Oct 01, 2019 9:55 pm

What I would suggest doing is putting it as a fraction over 2 so then you can easily multiply everything by 2. For example, if you have O2 on the reactants side and you need 3 oxygen to match the 3O on the product side you could just multiply the O2 by 3/2. This way when you multiply the entire equation by 2 you can easily cancel out the denominator and you are only left with the coefficient. Make sure when you multiply by 2 you are doing that to the whole equation; the 3O on the product side would become 6O and on the other side you would have 3O2.

Ying Yan 1F
Posts: 101
Joined: Fri Aug 02, 2019 12:16 am

Re: Tips on what number to multiply the entire equation if needed

Postby Ying Yan 1F » Tue Oct 01, 2019 10:29 pm

Sorry this is reptitive of other posts, and I actually didn't know to do this before myself(!), but the best way to balance a non whole number stoichometric coefficient is to write the coeifficient in improper fractions and multiply both the reactant and product compounds by the denominator of the fraction.

faithkim1L
Posts: 105
Joined: Fri Aug 09, 2019 12:17 am

Re: Tips on what number to multiply the entire equation if needed

Postby faithkim1L » Tue Oct 01, 2019 10:55 pm

The best way to ensure that you will end up with whole numbers on all of the stoichiometric coefficients is to multiply all the coefficients by the common denominator of the fractions. For example, if you had two fractions as stoichiometric coefficients with the denominators 2 and 3, you should multiply the whole equation by 6 in order to get rid of the 2 and 3 in the denominators.


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