Need help finding how many molecules fill 1 cubic cm....

[Krishna P]

Homework Statement

The question I'm working on is: If a layer of oleic acid is considered to be one molecule thick and the molecules are assumed to be essentially cubes, how many molecules would fill one cubic centimeter?

Homework Equations

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I've found the volume and area of the acid so that will give me the thickness:

0.5% oleic acid takes up 0.01 cubic centimetres. So volume of the acid is 0.005 cm3.

the area of the acid came out to 95cm2.

the thickness is then : 0.005/95 = 5.27 * 10^-5.

So if the thickness of oleic acid is found, do I just have to cube it then multiply by 100 to find out how many molecules in 1 cubic centimetre? Since oleic acid takes up 1/100 of a cubic centimetre and the molecules are assumed to be cubes...I don't know I'm lost here...

 

[RUber]

the thickness is then : 0.005/95 = 5.27 * 10^-5.

If you have the thickness, and you were told to assume the layer is 1 molecule thick and molecules are cubes...then you should be able to find the volume of 1 molecule.
Your thickness is in cm, right? So 1cm^3 / (volume of 1 molecule) = # of molecules in 1 cm^3.

 

[Krishna P]

Yea that makes sense, man I was thinking too hard about that one lol

 

[Borek]

0.5% oleic acid takes up 0.01 cubic centimetres. So volume of the acid is 0.005 cm3.

Something is wrong. 0.5% of 0.01 is not 0.005.

 

[RUber]

Good catch, Borek.
Also, a quick Google search confirms that molecules are on the scale of nanometers, 10^(-9)m, or 10^(-7)cm.

 

[Krishna P]

wow, no wonder my calculations were off, I kept thinking 0.5% was 0.5 ...