# Sphere equation?

1. Oct 24, 2005

### Math Is Hard

Staff Emeritus
OK, I'm clueless. I have this one homework problem where I am asked to represent a reaction with a "sphere equation". I have no idea what this is and I can't locate it in my book. Wasn't mentioned during lecture either.
Does anyone know what this means?

Here's the whole problem (maybe it will make sense in context):

a) write a chemical equation for the complete combustion of ethane.
b) represent this equation with Lewis structures.
c) represent this reaction with a sphere equation.

2. Oct 24, 2005

### Tide

I think they are asking you to draw a picture of the reaction using spheres to represent the atoms of each molecule.

3. Oct 24, 2005

### Math Is Hard

Staff Emeritus
hey Tide - thanks for responding. Do you mean kinda like a ball and stick diagram?

4. Oct 24, 2005

### Tide

Yes - but without the sticks!

5. Oct 24, 2005

### Math Is Hard

Staff Emeritus
6. Oct 25, 2005

### Chronos

Use x^2 + y^2 + z^2 = c to define the boundaries of spherical surfaces.

7. Oct 25, 2005

### Math Is Hard

Staff Emeritus
OK, it seems all she was looking for was a "ball and stick" drawing for each molecule in the reaction, but my space filling representations were acceptable. Darn chemistry! Too much artwork!

8. Oct 25, 2005

### Gokul43201

Staff Emeritus
MIH : What you want is called a Newman Diagram or Newman representation. That only tells you the conformational arrangement of atoms in a molecule (like ethane), but can not represent a reaction.

There's no such thing in chemistry as a sphere equation for a chemical reaction. At best, you can write an equation of state based on a hard-sphere interaction model, but that has nothing to do with this question.

Last edited: Oct 25, 2005
9. Oct 25, 2005

### Astronuc

Staff Emeritus
Description of hard sphere equation.

http://www.math.rutgers.edu/~lebowitz/PUBLIST/jll.pub_43.pdf

It would appear that one is to represent the equation of state as:

p/$\rho$kT = a($\rho$) + b($\rho$)/kT + c($\rho$)/(kt)2 + . . .

or see if this looks familiar

http://www.zae-bayern.de/ectp/abstracts/maeso1.html [Broken]

Have you seen the Carnahan-Starling equation yet?

This might be a question for Gokul.

Last edited by a moderator: May 2, 2017
10. Oct 25, 2005

### Math Is Hard

Staff Emeritus
ahh yes.. Newman Diagrams..
http://www.sollicitatiegesprek.nl/newman.jpg
Never heard of 'em!!!!
umm.. before you guys get too carried away, I should tell you this is a class for NON-science majors. I am lazy as hell, and want to do the LEAST amount of chemistry possible. Here's the description:
And the book is from our friends at The American Chemical Society.
http://www.chemistry.org/portal/a/c/s/1/acsdisplay.html?DOC=education\curriculum\context.html"

Last edited by a moderator: Apr 21, 2017
11. Oct 25, 2005

### Gokul43201

Staff Emeritus
That's the one !!!

Newman diagrams are very simple things with a fancy name. It's one of the first things you learn in organic chemistry.

Here's what one looks like :

http://www.chem.tamu.edu/organic/Spring2004/Review/Image382.gif [Broken]

Last edited by a moderator: May 2, 2017
12. Oct 25, 2005

### Math Is Hard

Staff Emeritus
hmm.. y'know Gokul, that doesn't look quite as scary as I imagined. I was curious about it, so I found some explanations of the diagrams here:
http://www.chem.ucalgary.ca/courses/351/Carey5th/Ch03/ch3-diagrams.html
so if I understood what they said correctly, that intersection in the front (of the diagram you posted) represents one carbon atom, and it has CH3, Br, and H attached to it. Then the circle would be another carbon atom (behind it) that the front one is bonded to, and it has CH3 and two H atoms attached to it.
http://www.chem.tamu.edu/organic/Spring2004/Review/Image382.gif [Broken]
So it's kind of like a perspective drawing?

Last edited by a moderator: May 2, 2017
13. Oct 25, 2005

### Gokul43201

Staff Emeritus
Yup. That's all it is !