Fractions
Moderators: Chem_Mod, Chem_Admin
Fractions
I know this was kind of addressed in a question someone asked earlier but I just wanted to ask if we would be marked down if we left the stoichiometric coefficient as a fraction? I know different professors prefer different things so I just wanted to clarify to see if it would necessarily be seen as a mistake if we left the fraction instead of multiplying both sides to get rid of it?
Re: Fractions
I'm guessing it's always best to make the fraction into an integer. I've heard that that is the way it's done in the scientific field and that it is preferred by many since it is more user friendly for future calculations.

 Posts: 102
 Joined: Wed Sep 18, 2019 12:18 am
Re: Fractions
In past chemistry classes, we have converted the fraction to a decimal and rounded to the correct number of sig figs. I assume Lavelle will prefer we do this since that is typically how figures are reported on lab reports and other experimental documents.

 Posts: 76
 Joined: Wed Sep 18, 2019 12:16 am
Re: Fractions
I would assume changing the fraction to an integer is the only way you would get full credit. The purpose of making a fraction is so that it's easy to convert all of the elements coefficients to whole numbers.

 Posts: 69
 Joined: Thu Jul 11, 2019 12:17 am
Re: Fractions
They might give you partial credit though even if you leave it in fractions as long as you show your work.

 Posts: 110
 Joined: Sat Aug 24, 2019 12:17 am
Re: Fractions
I would change the fraction to an integer since the equation is supposed to represent the exact reaction with the smallest whole integers, not a fraction of it.

 Posts: 104
 Joined: Sat Aug 17, 2019 12:17 am
Re: Fractions
I would personally refrain from keeping fractions in the formula because of how easy of a fix it is. All you really have to do is multiply everything by the denominator to remove the fraction. It's an easy fix for something you won't have to worry about later.

 Posts: 50
 Joined: Wed Sep 18, 2019 12:21 am
Re: Fractions
Dr.Lavelle states it's better that the fractions are left in whole numbers when balancing equations. Since he prefers it that way, I think it is better to keep the habit of doing it often when it comes down to fractions in a chemical equation.
Re: Fractions
You should multiply all coefficients to make them whole integers, especially if the question is asking for a molecular or empirical formula.

 Posts: 101
 Joined: Wed Sep 18, 2019 12:20 am
Re: Fractions
It's generally good practice to convert all the coefficients to integers, as that gives the most accurate representation of the chemical reaction.
Re: Fractions
I would convert all fractions into an integer but using fractions is a good way to keep the numbers straight and helps initially with balancing.

 Posts: 50
 Joined: Sat Sep 07, 2019 12:18 am

 Posts: 50
 Joined: Thu Jul 25, 2019 12:17 am

 Posts: 100
 Joined: Wed Sep 18, 2019 12:15 am

 Posts: 63
 Joined: Fri Sep 27, 2019 12:30 am

 Posts: 7
 Joined: Tue Nov 13, 2018 12:18 am
Re: Fractions
The coefficients should always be whole numbers even at their empirical formula notation. Just make them whole numbers, if anything at least at that point you would have gotten your molecular formula. Hope this helps.

 Posts: 107
 Joined: Wed Sep 18, 2019 12:21 am
Re: Fractions
I remember Prof. Lavelle suggesting that we should convert the fractional stoichiometric coefficients into whole integers.

 Posts: 102
 Joined: Fri Aug 30, 2019 12:17 am
Re: Fractions
It should always be expressed as a whole number. However, during the thermodynamics units, it would be beneficial to leave it as a fraction, but for now just express them as whole numbers.

 Posts: 94
 Joined: Sat Sep 14, 2019 12:16 am
Re: Fractions
I would convert it to an integer as the TAs always change it and they are the ones that grade the tests and homework.

 Posts: 41
 Joined: Wed Feb 20, 2019 12:15 am
Re: Fractions
its useful to use fractions in the process of figuring it out then multiplying the whole equation (both sides) by a least common denominator.

 Posts: 15
 Joined: Wed Feb 26, 2020 12:15 am
Re: Fractions
My best guess is just to turn the fractions into whole numbers just to be safe, because in the lecture the professor did mention that stoichiometric coefficients should not be fractions, but ultimately I think it just depends on if the question specifies otherwise.

 Posts: 21
 Joined: Wed Sep 30, 2020 10:03 pm
Re: Fractions
I definitely agree that stoichiometric coefficients should be integers, but would there be a case where the question would tell us to leave it as a fraction?

 Posts: 21
 Joined: Wed Sep 30, 2020 9:54 pm
Re: Fractions
I think in most cases we should always leave the Stoichiometric coefficients in integers, for example, in the butane combustion class example, professor Lavelle multiplied by all stoichiometric coefficients by 2 in order to have every coefficient as an integer. Unless the question specifically says "leave the stoichiometric coefficient in fraction form" (which I think is not very common), then we leave them in fractions.
Hope it helps!
Hope it helps!

 Posts: 15
 Joined: Wed Sep 30, 2020 10:00 pm
Re: Fractions
KSong_1J wrote:I know this was kind of addressed in a question someone asked earlier but I just wanted to ask if we would be marked down if we left the stoichiometric coefficient as a fraction? I know different professors prefer different things so I just wanted to clarify to see if it would necessarily be seen as a mistake if we left the fraction instead of multiplying both sides to get rid of it?
I think it's a stated rule never to have fractions as stoichiometric coefficients when balancing chemical reactions! (Or it's highly recommended to put them as whole numbers)

 Posts: 14
 Joined: Wed Sep 30, 2020 9:33 pm
Re: Fractions
It is technically correct if you leave the coefficients as fractions but it will generally make your math much easier if you try to simplify and have whole numbers.

 Posts: 9
 Joined: Wed Sep 30, 2020 9:34 pm
Re: Fractions
I think in one of the modules Prof. Lavelle specifically states that you need to simplify out fraction stoichiometric ratios. Hope this helps!

 Posts: 16
 Joined: Wed Sep 30, 2020 9:46 pm
Re: Fractions
Hello! I think it is preferred to have stoichiometric coefficients as whole numbers, since Dr. Lavelle mentioned how to do it.

 Posts: 15
 Joined: Wed Sep 30, 2020 10:03 pm
Re: Fractions
While using fractions when balancing out chemical equations is totally fine and in many cases useful/easier, it is always best to convert it into an integer.

 Posts: 15
 Joined: Wed Sep 30, 2020 9:53 pm
Re: Fractions
I think it is fine to have a fraction as the coefficient. But it will be more convenient if the fractions are converted into whole numbers, especially when you need to do further calculations such as finding the molecular formula etc.

 Posts: 15
 Joined: Wed Sep 30, 2020 9:49 pm
Re: Fractions
I think Professor Lavelle said in a previous lecture that chemists prefer coefficients to be integers instead of fractions. I know it seems bothersome to convert decimals and fractions into integers, but I think the safe bet is to convert them into integers.

 Posts: 15
 Joined: Wed Sep 30, 2020 9:42 pm
Re: Fractions
To change it to integers, normally wouldn't you multiply the entire equation by the denominator of the coefficient that's not a whole number

 Posts: 13
 Joined: Wed Sep 30, 2020 9:41 pm
Re: Fractions
I think it is always safe to convert the fractions into integers for the stoichiometric coefficients in a balanced equation. I remember there was this one multiplechoice question in the postassessment modules for balancing equations, and the correct answer had stoichiometric coefficients with integers rather than with fractions.

 Posts: 12
 Joined: Wed Sep 30, 2020 9:36 pm
Re: Fractions
I would definitely say to make all your stoichiometric coefficients into integers. I know Dr. Lavelle mentioned to do so in a lecture, and the UA who hosted tonight's Workshop also said to be sure to convert them into whole numbers, so I would put in that extra step just to be safe. You can always ask your TA to double check how they will be grading, though. :)

 Posts: 25
 Joined: Wed Sep 30, 2020 9:55 pm
 Been upvoted: 1 time
Re: Fractions
Whenever Dr. Lavelle has done these types of problems, he always makes sure that the final answer is an integer. In his module videos, he specifically showed that the last step in balancing an equation was to multiply by a factor to get an integer.
Return to “Balancing Chemical Reactions”
Who is online
Users browsing this forum: Mohamed Mido and 1 guest