## Fundamental Exercises E27

Searra Harding 4I
Posts: 68
Joined: Fri Sep 28, 2018 12:29 am

### Fundamental Exercises E27

This exercise says "Calculate the mass, in grams, of one water molecule". Then it says "Determine the number of water molecules in 1.00 kg of water." I know that for the first one I need to go from molecules to moles to grams. To go from moles to grams I can use molar mass. But how would I do the other part of it?

Te Jung Yang 4K
Posts: 63
Joined: Fri Sep 28, 2018 12:18 am

### Re: Fundamental Exercises E27

To find the number of water molecules in 1.00 kg of water, you would have to convert the 1.00 kg of water to moles of water (using the molecular mass of water and the relevant equation - don't forget to convert kg to g when using the equation!).

Then, once you have the moles of water in 1.00 kg of water, you would multiply the moles of water by Avogadro's number (6.022 * 10^23), which is the number of molecules in one mole of any substance, to get your final answer.

Hope I helped!

Samantha Chang 2K
Posts: 69
Joined: Fri Sep 28, 2018 12:17 am

### Re: Fundamental Exercises E27

1. Convert 1Kg H2O to grams
2. Convert the grams of H2O to moles using molar mass of H2O (you can add masses up using the periodic table)
3. Convert the moles to molecules using Avogadro constant (6.022*10^23)
:)

Searra Harding 4I
Posts: 68
Joined: Fri Sep 28, 2018 12:29 am

### Re: Fundamental Exercises E27

Te Jung Yang 1G wrote:To find the number of water molecules in 1.00 kg of water, you would have to convert the 1.00 kg of water to moles of water (using the molecular mass of water and the relevant equation - don't forget to convert kg to g when using the equation!).

Then, once you have the moles of water in 1.00 kg of water, you would multiply the moles of water by Avogadro's number (6.022 * 10^23), which is the number of molecules in one mole of any substance, to get your final answer.

Hope I helped!

This is very helpful thank you!