[parywinkle]

Hi this is the question from my practice problem set #4:

http://postimg.org/image/6mt3coash/

and here's the solution to #4:

http://postimg.org/image/nbuj8l7dt/

Can someone explain where and how they are getting the concentration of H2O? I get the 90/100% ratio but the concentration of H2O I have no idea where to get.
Also part b) makes so sense at all

I would appreciate your input thank you!

[kelvinLTR]

I think the answer lies in 'pseudo-order'. Do some research on it

[aHerraez]

The way the concentration of water is calculated is detailed there in the answer that you linked:

1. we know how many grams of water there are per liter of solution

2. we know the molar mass of water from its formula

So you may calculate its molar concentration as indicated in the solution.
Do you get it?