Fractions in Balancing Equations

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Ghadir Seder 1G
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Joined: Sat Sep 14, 2019 12:17 am

Fractions in Balancing Equations

Postby Ghadir Seder 1G » Thu Oct 03, 2019 6:16 pm

How and when do you know when to use fractions when balancing chemical equations?
Thanks :)

Andrew Pfeiffer 2E
Posts: 54
Joined: Sat Sep 28, 2019 12:16 am

Re: Fractions in Balancing Equations

Postby Andrew Pfeiffer 2E » Thu Oct 03, 2019 6:34 pm

Fractions can be used as an intermediate step when balancing equations, but you never want fraction coefficients in your final balanced equation.

For example...

Given the unbalanced equation C4H10 + O2 ---> CO2 + H2O.

First you would balance H and then balance O. After that, you should have
C4H10 + 13/2 O2 ---> 4 CO2 + 5 H2O

Remember that stoichiometric coefficients should be whole numbers, so multiply everything by 2 to get rid of the improper fraction and get

2 C4H10 + 13 O2 ---> 8 CO2 + 10 H2O.

Hope this was helpful!

Abby Soriano 1J
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Joined: Sat Aug 24, 2019 12:16 am

Re: Fractions in Balancing Equations

Postby Abby Soriano 1J » Thu Oct 03, 2019 6:40 pm

There's never really a time when you should be wanting to use fractions when balancing equations since you want all of your stoichiometric coefficients to be whole numbers. Usually you end up needing to use fractions when there's no other way to balance something.

For example, if you find that there are 5 oxygens on the right side of an equation but the only oxygen on the left side has a subscript of 2 (there's no coefficient that could turn the 2 into a 5), then you might considering using the fraction of 5/2 as the coefficient in front of the oxygen on the left. This is fine, just remember to multiply the entire equation afterwards by 2 to cancel out the fraction so you're left with only whole numbers!

HuyHa_2H
Posts: 60
Joined: Wed Sep 11, 2019 12:15 am

Re: Fractions in Balancing Equations

Postby HuyHa_2H » Thu Oct 03, 2019 6:43 pm

Typically, if you can't use a whole number as a stoichiometric coefficient for whatever it is you're balancing is when you use a fraction. It's so you can just multiply every coefficient in the equation with the denominator of the fraction to get all the coefficients as whole numbers without messing up the mole ratios.

Destiny_Ryales_3J
Posts: 38
Joined: Fri Sep 28, 2018 12:28 am

Re: Fractions in Balancing Equations

Postby Destiny_Ryales_3J » Thu Oct 03, 2019 7:20 pm

Make sure to never leave your equation with fractions in it, just multiply every coefficient by the lowest number that would make the fractional coefficient a whole number!!!!!

Michelle N - 2C
Posts: 69
Joined: Wed Sep 18, 2019 12:19 am

Re: Fractions in Balancing Equations

Postby Michelle N - 2C » Thu Oct 03, 2019 9:25 pm

There will be cases where fractions are the only solution, but as long as you multiply every coefficient (both on reactant and products side) by the denominator, then you should be fine! The final equation should not have any fractions though, at least from what I know of.

Abigail_Hagen2G
Posts: 62
Joined: Fri Aug 09, 2019 12:17 am

Re: Fractions in Balancing Equations

Postby Abigail_Hagen2G » Thu Oct 03, 2019 10:23 pm

The answer shouldn't be left in fractions

805317518
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Joined: Wed Sep 11, 2019 12:16 am

Re: Fractions in Balancing Equations

Postby 805317518 » Thu Oct 03, 2019 11:48 pm

The answer should never be in fractions, but also make sure that it's simplified! I've had times where I multiplied by 2 more often than I should, making my coefficients bigger than necessary

Brianna Becerra 1B
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Joined: Fri Aug 02, 2019 12:16 am

Re: Fractions in Balancing Equations

Postby Brianna Becerra 1B » Fri Oct 04, 2019 11:14 am

Fractions can be used when balancing equations as sometimes, the lowest balance leaves us with a fraction. The coefficients however in the answer, need to be whole numbers. Luckily, changing from fractions to whole numbers can be done simply by multiplying all of the balanced equations stoichiometric coefficients by the denominator of the fraction. This does not affect the equation and would be the correct answer. When balancing equations, do not leave the answer as having a fraction coefficient.

Eva Zhao 4I
Posts: 61
Joined: Sun Sep 29, 2019 12:16 am

Re: Fractions in Balancing Equations

Postby Eva Zhao 4I » Fri Oct 04, 2019 12:06 pm

Stoichiometric coefficients must typically be a whole number. If you do ever have a fraction after balancing the equation, multiply the fraction by the lowest number that would make it a whole number.

AmyL_3L
Posts: 50
Joined: Fri Aug 09, 2019 12:17 am

Re: Fractions in Balancing Equations

Postby AmyL_3L » Sat Oct 05, 2019 2:35 pm

Fractions should not be used as stoichiometric coefficients. Whenever there is a fraction, you need to multiply every stoichiometric coefficient by the denominator to create whole numbers while maintaining the mole ratio.

Nuoya Jiang
Posts: 54
Joined: Sat Sep 14, 2019 12:17 am

Re: Fractions in Balancing Equations

Postby Nuoya Jiang » Sat Oct 05, 2019 3:32 pm

After you finish balancing the chemical equations, always remember to convert fractions into integrals because fractions should never appear in chemical equations to the definition of stoichiometric coefficients.


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