Fractions in front of compounds

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005095564
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Joined: Wed Sep 18, 2019 12:18 am

Fractions in front of compounds

Postby 005095564 » Thu Oct 03, 2019 1:12 pm

When balancing out equations, we should have whole numbers always. Do we only multiply each compound on both sides of the equation when there is a fraction on either side of the problem or would there be other scenarios when we would multiply to each side?

Astrid Lunde 1I
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Joined: Sat Sep 07, 2019 12:16 am

Re: Fractions in front of compounds

Postby Astrid Lunde 1I » Thu Oct 03, 2019 1:24 pm

In order to balance an equation that has a fraction you have to multiply the entire equation by the smallest factor to get rid of the fraction.

anjali41
Posts: 109
Joined: Fri Aug 09, 2019 12:15 am

Re: Fractions in front of compounds

Postby anjali41 » Thu Oct 03, 2019 1:29 pm

You would have to multiply both sides of the equation if there was a fraction. If you only multiplied the stoichiometric coefficients on one side, the equation would become unbalanced again, as the multiplied sides would have more atoms than the non-multiplied side. So in all situations, you must multiply both sides to eliminate the fractions.

haileyramsey-1c
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Joined: Thu Jul 25, 2019 12:18 am

Re: Fractions in front of compounds

Postby haileyramsey-1c » Thu Oct 03, 2019 3:06 pm

The only scenario where you would multiply both sides is if there were fractions involved. When balancing chemical equations you want to have the lowest integer numbers as coefficients. If you had coefficients of 2,4,6,2, for example, you would divide each coefficient by 2 to obtain a correctly balanced equation. Also, what you do to one side you must do to the other.

serenabirkhoff_1K
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Joined: Sat Aug 17, 2019 12:15 am

Re: Fractions in front of compounds

Postby serenabirkhoff_1K » Thu Oct 03, 2019 4:34 pm

Just like in an math equation what you do to one side you must do to another. The easiest way for me to think about it is if you have a fraction and need to make is a whole number, multiple every coefficient by the denominator of that fraction (including that fraction), in order to get a balanced equation with all whole numbers.

Tooba_1A
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Joined: Wed Sep 11, 2019 12:16 am

Re: Fractions in front of compounds

Postby Tooba_1A » Fri Oct 04, 2019 12:15 am

Considering that we only multiply the whole equation since we're trying to get rid of the divisor from the fraction, we don't have any other use of multiplying the whole equation, unless if it's to get rid of a fraction. This is because stoichiometric is preferred to be in whole integers, and having fractions throws this dynamic off.

Caitlin Ciardelli 3E
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Joined: Wed Sep 18, 2019 12:19 am

Re: Fractions in front of compounds

Postby Caitlin Ciardelli 3E » Fri Oct 04, 2019 12:01 pm

You want to multiply because we want whole moles in the stoichiometric coefficients.The only time you need to worry about multiplying is when the coefficients don't come out to be whole numbers when you divide by the lowest number. The only other time you need to worry about multiplication is if the question asks for the molecular formula.

Sean Sugai 4E
Posts: 56
Joined: Wed Sep 11, 2019 12:17 am

Re: Fractions in front of compounds

Postby Sean Sugai 4E » Fri Oct 04, 2019 12:15 pm

When you have a fraction as a stoichiometric coefficient, multiply both sides of the equation by the denominator of the fraction.
For example, NH3 + O2 => NO + H2O, depending on the way you balance the equation, you might get:
2 NH3 + 5/2 O2 => 2 NO + 3 H2O
In this case, you multiply both sides of the equation by 2 to get rid of the 5/2 next to the O2, which would make the balanced equation:
4 NH3 + 5 O2 => 4 NO + 6 H2O

Emily Mendez 4C
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Joined: Wed Nov 14, 2018 12:19 am

Re: Fractions in front of compounds

Postby Emily Mendez 4C » Fri Oct 04, 2019 12:38 pm

A chemical equation always has to be balanced. In order for the whole chemical equation to be balanced when their is a fraction involved, you have to multiply the entire equation by the smallest factor to get all the whole numbers. Whole numbers are essential since it will make it easier for chemists to read and it looks a bit more clean and professional.

Sanjana Borle 2K
Posts: 111
Joined: Fri Aug 09, 2019 12:15 am

Re: Fractions in front of compounds

Postby Sanjana Borle 2K » Fri Oct 04, 2019 1:29 pm

Because it doesn't make much sense to have a fraction of a mole (since a mole is not a perfect number) it should be multiplied until all stoichiometric coefficents are whole numbers.

Fdonovan 3D
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Joined: Sat Aug 17, 2019 12:16 am

Re: Fractions in front of compounds

Postby Fdonovan 3D » Fri Oct 04, 2019 4:56 pm

Yes! You need to multiply everything by the same number in order to keep the chemical equation balanced. Think about it like an algebra problem-- whatever you do to one part of the equation you have to do to everything.

Juana Abana 1G
Posts: 100
Joined: Wed Sep 18, 2019 12:15 am

Re: Fractions in front of compounds

Postby Juana Abana 1G » Fri Oct 04, 2019 6:31 pm

Yes, you have to multiply both sides of the equation by the smallest factor in order to get rid of the fraction.

Ruth Glauber 1C
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Joined: Wed Sep 18, 2019 12:20 am

Re: Fractions in front of compounds

Postby Ruth Glauber 1C » Sat Oct 05, 2019 5:40 pm

You should always multiply to eliminate fractions across the entire equation, to ensure it's balanced on both sides.


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