How Do You Calculate the Number of Coulombs in a Glass of Water?

[LTech221]

Hi everyone its my first time here, read the forums greatly though and have been a help in understanding but now I am completely lost on this problem: Calculate the number of coulombs of positive charge in 250 cm^3 of (neutral) water (about a glass full). So far I tried converting the volume to m^3 (2.5E-4 m^3, not sure if it matters.)then tried tried dividing by colulomb's constant and ended up with units kg/s^2 * c^2 and don't know where to go from there. I am not sure if I really approached this problem right as the section it supposedly comes from keeps mentioning q=ne, but I cannot relate that directly. I am thinking I am missing something inbetween , any ideas to go about the problem would be appreciated.

 

[Philcorp]

if you know the volume of the water then it should be easy enough for you to convert that into an equivalent mass. From there you should know the ratio of moles to grams for water ( i think its something like 18.02g/mol). This allows you to convert you volume from grams into moles. Now you can use Avagadro's number (6.02x10^23) to know the number of molecules in your sample. From there you know that each water molecule is made up of H_2O...so that's 10 protons. And each proton have 1.6x10^-19 C of charge.

There you have it!

 

[LTech221]

Ahhh, that's what i was missing, thanks for the help