- Sea water contains a lot of different dissolved salts. Do you want the concentration of the NaCl in sea water, or the total salt concentration as NaCl?
- What part of the Pacific Ocean?
As you can see from this map of Pacific ocean salinities [NOAA], the concentration varies with location. (Click the image for a full size version).
Once you've decided whether you want actual NaCl molarity or total salt as NaCl molarity, and once you've picked a spot on the map above,
you can convert units to obtain a molarity of NaCl from a salinity in PSS. Suppose your spot has a salinity of 35 PSS. Then your
calculation will look like
PSS g sea salt/kg seawater g Cl/kg seawater
The PSS stands for "Practical Salinity Scale". It's defined in terms of electrical conductivity measurements but for your purposes,
you can probably use the following approximate conversion factors:
mol Cl/kg seawater mol NaCl/kg seawater mol NaCl/L seawater
1 PSS unit = 1 g sea salt/ kg seawater
1.80655 g sea salt = 1 g Cl
The last step converts kg seawater to L seawater, and you'll need the density of seawater for that.
It's between 1.02 g/mL and 1.07 g/mL, but if you want precision you'll have to look up the number in a physical oceanography text.
(I can't give you a number because the density will depend on the salinity you use- and on the ocean temperature and pressure).
- NOAA Map The salinity map was obtained from the National Oceanic and Atmospheric Administration Climate Server at
http://teal.wrc.noaa.gov/tmap-bin/climate_server (now apparently offline).
Author: Fred Senese firstname.lastname@example.org