question on finding the volume of vapor and the volume of liquid


by rinchan4
Tags: liquid, vapor, volume
rinchan4
rinchan4 is offline
#1
Nov9-09, 08:47 PM
P: 11
1. The problem statement, all variables and given/known data

On a hot 35 degrees celsius day you perspire 1.0 kg of water during your workout.
A) what volume is occupied by the evaporated water?
B) By what factor is this larger than the volume occupied by the liquid water?

2. Relevant equations

PV=nRT
PV=NKbT
density of water is 1000 kg/m3= M/V
n=Mass/ Molar mass


[b]3. The attempt at a solution[/b

I really have no idea on how to start this problem. I did solve for n=M/Mmol=1000g/18.02g/mol= 55.49 moles but i don't even know if I need it. Any help would be greatly appreciated.
Phys.Org News Partner Science news on Phys.org
Going nuts? Turkey looks to pistachios to heat new eco-city
Space-tested fluid flow concept advances infectious disease diagnoses
SpaceX launches supplies to space station (Update)
rinchan4
rinchan4 is offline
#2
Nov9-09, 09:26 PM
P: 11
I just need a hint to get going in the right direction. I'm thinking that this problem may have something to do with the phase diagram of water?
Redbelly98
Redbelly98 is offline
#3
Nov10-09, 09:23 PM
Mentor
Redbelly98's Avatar
P: 11,986
Welcome to PF.

What's missing here is the pressure of water. Has your class or book discussed the concept of vapor pressure ? There might be a table of water's vapor pressure in your book, for different temperatures. That information is needed to solve this.

rinchan4
rinchan4 is offline
#4
Nov10-09, 09:36 PM
P: 11

question on finding the volume of vapor and the volume of liquid


Yeah we didn't talk at all about vapor pressure and the only thing that it says in my book is that we can ignore vapor pressure if we keep the tempature low. I did find that the vapor pressure of water is 2.4 kPa and 20 degrees celcius.
rinchan4
rinchan4 is offline
#5
Nov10-09, 09:43 PM
P: 11
I tried using the density of vapor 0.0022(since i knew the mass of 1kg) and from that find the volume of 454.5m3 but that wasn't right
ideasrule
ideasrule is offline
#6
Nov10-09, 09:51 PM
HW Helper
ideasrule's Avatar
P: 2,324
You had pV=nRT and you had both n and T, so all you need is p. Imagine trapping all of the water vapor in a box that's free to expand or contract whenever it needs to. What would the pressure of the water vapor be?
rinchan4
rinchan4 is offline
#7
Nov10-09, 09:57 PM
P: 11
would be the same as the atmospheric pressure of 101300 Pa?
ideasrule
ideasrule is offline
#8
Nov10-09, 09:58 PM
HW Helper
ideasrule's Avatar
P: 2,324
Yeah.
rinchan4
rinchan4 is offline
#9
Nov10-09, 10:02 PM
P: 11
so then...
P= 101300 Pa
n= 1000/18.02=55.49moles
T= 308 k
R=8.31
Solve for V and I get 1.402 m3
rinchan4
rinchan4 is offline
#10
Nov10-09, 10:09 PM
P: 11
awesome thank you so much. I was able to figure out part b. Thank you!!! :)


Register to reply

Related Discussions
Really quick question about finding specific volume in thermodynamics Advanced Physics Homework 2
Help With Gas/Liquid Pressure/Volume Introductory Physics Homework 1
Spray Volume/liquid Displacement General Engineering 1
volume of a liquid in a container Introductory Physics Homework 5
Liquid gas volume in Cylinder Materials & Chemical Engineering 1