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Topic: Empirical vs molecular formulas  (Read 2973 times)

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Offline stormaktstid

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Empirical vs molecular formulas
« on: October 22, 2017, 03:05:50 PM »
Glucose, acetic acid and formaldehyde have the same empirical formula, but different molecular formula so why do they have different properties. How does changing molecular formula change the properties of compound?

Offline chenbeier

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Re: Empirical vs molecular formulas
« Reply #1 on: October 22, 2017, 03:25:01 PM »
Its not only a matter of mathematics. It the structure of the molecules. H2C=O Formaldehyde, CH3COOH Acetic acid and glucose CH2OH-CHOH-CHOH-CHOH-CHOH-CHO .


Offline stormaktstid

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Re: Empirical vs molecular formulas
« Reply #2 on: October 22, 2017, 03:28:00 PM »
but why do the properties change when molecular formula change but empirical formula stays the same?

Offline chenbeier

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Re: Empirical vs molecular formulas
« Reply #3 on: October 22, 2017, 04:05:47 PM »
I wrote the 3 molecular formulas. You can see they all look different, so also the properties will be different. Interaction of the atoms of the molecules. The empiric formula is only a mathematical result.

Offline stormaktstid

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Re: Empirical vs molecular formulas
« Reply #4 on: October 22, 2017, 05:10:09 PM »
but why?

Offline Borek

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Re: Empirical vs molecular formulas
« Reply #5 on: October 22, 2017, 05:34:13 PM »
First things first: explain what you know about the difference between empirical formula and molecular formula. What does each tell us about the compound?
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Offline Arkcon

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Re: Empirical vs molecular formulas
« Reply #6 on: October 22, 2017, 05:41:27 PM »
There isn't much more left to say.  You can see that chenbeier: has done some work for you, and given you the molecular formulas.  Your empirical formula is just a shorthand reducing the numbers of atoms to the least common denominator.  Glucose is nothing like formaldehyde structurally -- it isn't even 6 formaldehydes strung together, some groups are different along the molecule.

but why?

Kindly don't behave this way on our forum.  No one older than 5 years old is permitted, in this world, to just ask "But why?"  Use the definition of empirical formula to see for yourself how the empirical formula should be used.

Kindly, stormaktstid:, I'd like to welcome you and all the new chemists to the Chemical Forums.  But I'd like to ask you to trouble yourself to read our Forum Rules{click}. You already accepted them when you signed up for our forum, and they apply to you, whether you agree with them or not, or even if you're unaware of them. 

Our rules specify that we want to see your work, and then, we want to give you hints, so that you learn for yourself.  It doesn't matter if you're a new student, or a dedicated amateur, we need to know what you know, and what you think, so we know what level you're at, so we can give useful hints, so your knowledge can grow.   
Hey, I'm not judging.  I just like to shoot straight.  I'm a man of science.

Offline stormaktstid

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Re: Empirical vs molecular formulas
« Reply #7 on: October 22, 2017, 06:22:46 PM »
im asking why the physical properties change. i know what the difference is between empirical and molecular formulas, i've taken hon. chemistry but they don't explain why if you double the chemical formula you get new properties

Offline Arkcon

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Re: Empirical vs molecular formulas
« Reply #8 on: October 22, 2017, 06:33:07 PM »
You question stay highly hypothetical so far, and that's great for philosophy, or an argument, but bad for science.  Let's try this a different way.

Build a table of properties.  Use these compounds as headers, and list the properties you want to talk about.  And let's see if there's a pattern we can find.
Hey, I'm not judging.  I just like to shoot straight.  I'm a man of science.

Offline stormaktstid

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Re: Empirical vs molecular formulas
« Reply #9 on: October 22, 2017, 07:25:50 PM »
i dont wanna make no tables. like why cant you just tell me the answer or say you dont know if you dont know bruh

Offline Borek

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Re: Empirical vs molecular formulas
« Reply #10 on: October 23, 2017, 02:20:34 AM »
i dont wanna make no tables. like why cant you just tell me the answer or say you dont know if you dont know bruh

If you don't want to make an effort - why should we?

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