Finding the volume of one water molecule

In summary, Niles tried to calculate the volume of 1 water molecule using the densities of H and O, but he ran into trouble because the volumes of atoms involved partially overlapped. He recommends using a "density-method" to calculate the volume of a molecule.
  • #1
Niles
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Homework Statement


Hi guys

I know the molar mass (i.e. g/mole) of H and O, but from this, then how do I find the volume of 1 water molecule? I know the densities of H and O as well, from which I can find the volume of H and O. Do I just add these, one of V_oxygen and two of V_hydrogen (I know the correct value is 2.99E-29 kg^3)? I tried doing this, but it did not give me the correct value.


Niles.
 
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  • #2
You better start with water density (1g/mL) and calculate how many molecules in 1mL. Assuming final volume of a molecule is a sum of volumes of atoms is a sure way of getting it wrong.

How come final answer is in kg3? You sure you didn't mean m3?

--
 
  • #3
I mixed it up - the volume is of course in m^3. Regarding the density, then what I wanted was a general way of doing it, because I might not always know the density of the molecule as a whole, but only each atomic-part of the molecule.

So, how should I do it? I can find V_H and V_O, but adding them as 2V_H + V_O doesn't give me the correct result.
 
  • #4
Niles said:
So, how should I do it? I can find V_H and V_O, but adding them as 2V_H + V_O doesn't give me the correct result.

That's because this is a faulty approach. When atoms bind their volumes partially overlap.

And I am not aware on any general method that will let you calculate volume of the molecule from the volumes of atoms involved. It just doesn't want to be that easy. You can try to calculate molecule shape using Schroedingers equation and quantum chemistry methods, but it is not an easy task.
 
  • #5
Ok, then the "density-method" is the way to go. Thanks!Niles.
 

Related to Finding the volume of one water molecule

1. How do you calculate the volume of one water molecule?

To calculate the volume of one water molecule, you can use the formula for the volume of a sphere, which is (4/3)πr^3, where r is the radius of the molecule. The radius of a water molecule is approximately 0.0000000000000022 meters.

2. What is the volume of one water molecule in cubic centimeters?

The volume of one water molecule in cubic centimeters is approximately 0.00000000000000000000000000000000000000000008 cubic centimeters. This is an extremely small volume, as water molecules are very tiny.

3. How does the volume of one water molecule compare to other molecules?

The volume of one water molecule is relatively small compared to other molecules. For example, the volume of one oxygen molecule is approximately 0.000000000000024 cubic centimeters, making it slightly larger than a water molecule.

4. Can the volume of one water molecule change?

The volume of one water molecule is constant and does not change. However, the arrangement of water molecules can change, such as when water freezes or evaporates. In these cases, the spacing between water molecules changes, but the volume of each individual molecule remains the same.

5. Why is it important to know the volume of one water molecule?

Knowing the volume of one water molecule is important for understanding the properties and behavior of water at a molecular level. It also helps in various scientific experiments and studies, such as understanding the density and structure of water, and how it interacts with other molecules.

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