Sea Water as an Electrolyte

Abstract

The composition of the major components of sea water has been measured by a number of researchers over the years. The relative molar concentration of the major cations (Na+, Mg2+, Ca2+, K+, Sr2+) and anions (Cl-,SO 4 2- , HCO 3 - , Br-, CO 3 2- , B(OH) 4 - , F-) in the major oceans has been shown to be constant. These major components of sea water contribute to the physical chemical properties of the oceans. Since the major components of sea water are constant throughout the oceans (The Marcet Principle), it is possible to treat ocean waters as an electrolyte solution (sea salt) with a dash of the non-electrolyte boric acid. This simplifies the physical chemistry of sea water solutions and other natural waters. Some minor components (SiO2, NO 3 - and PO 4 3- ) that are added to the oceans from the bacterial oxidation of plant material can also have a minor effect on the properties of deep waters. In this chapter, I will review how one treats sea water as a multi-component solution, and how the major components of sea water contribute to its physical and chemical properties. First we will examine the composition of sea water and the development of salinity.