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

1. Oct 7, 2015

### Krishna P

1. The problem statement, all variables and given/known data
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?

2. Relevant equations\

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...

2. Oct 7, 2015

### RUber

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.

3. Oct 7, 2015

### Krishna P

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

4. Oct 7, 2015

### Staff: Mentor

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

5. Oct 7, 2015

### 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.

6. Oct 8, 2015

### Krishna P

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