Sea-water density

U.S. Naval Hydrographic Office. 1952. Tables for Sea Water Density, Publication No. 615, U.S. Naval Hydrographic Office, Washington, DC. 

The density of the chemical warfare agent is another factor which will decide if the agent will sink to the sea-bed or rise to the surface of the water. With the exception of tabun (density 1.07 g/cm ) all the agents of concern have a higher density than the Baltic sea water (density approximately 1.08 g/cm ). Based upon this, it can be assumed that dumped chemical warfare agents will normally not rise to the surface of the water and drift there. 

Pycnocline Sudden change in sea-water density as depths increase. 

Substances such as brass, wood, sea water, and detergent formulations are mixtures of chemicals. Two samples of brass may differ in composition, colour and density. Different pieces of wood of the same species may differ in hardness and colour. One sample of sea water may contain more salt and different proportions of trace compounds than another. Detergent formulations differ... 

Since, however, density is affected to a considerable degree by temperature, and since its accurate measurement demands special apparatus and great care, it is not a reliable measure of the strength of sea water. 

By virtue of the high breakdown potential of the oxide film (approximately 155 V in sea water and 280 V in low conductivity water of pH = 7) tantalum has found use as a substrate for platinum in impressed-current cathodic-protection anodes, which can be used at high impressed voltages (50 V) and high current densities. However, because of its lower cost, niobium is preferred for systems that have to operate at high voltages... 

Current density requirements depend on the environment, galvanic effects, velocities and other factors influencing polarisation. In the absence of galvanic influences or other secondary effects 30mA/m may be sufficient in sea-water to maintain adequate polarisation for protection once it has been achieved it is however normally necessary to apply 100-150 mA/m to achieve initial polarisation within a reasonable period and if rapid protection is required, current densities as high as 500 mA/m may be applied. 

Cultures of G. polyedra (L. polyedrum) are grown at 20 5°C in a supplemented sea water medium (Hastings and Sweeney, 1957 Hastings and Dunlap, 1986), under cool-white fluorescent lighting of a 12-hr light/12-hr dark cycle. The cultures are inoculated at densities of 100 to 500 cells/ml. After 2-4 weeks, cells are harvested by vacuum filtration on a filter paper at cell densities of 7,000-15,000 cells/ml, yielding 0.3-0.7 g wet cells per liter of culture. 

Before describing these thermodynamic variables, we must talk about their properties. The variables are classified as intensive or extensive. Extensive variables depend upon the amount while intensive variables do not. Density is an example of an intensive variable. The density of an ice crystal in an iceberg is the same as the density of the entire iceberg. Volume, on the other hand, is an extensive variable. The volume of the ocean is very different from the volume of a drop of sea water. When we talk about an extensive thermodynamic variable Z we must be careful to specify the amount. This is usually done in terms of the molar property Zm, defined as... 

The neutral electrolyte, often sea water, can be replaced by aqueous NaOH providing that the anode is alloyed with magnesium and tin. Alkaline aluminium-air cells have significantly greater power densities. 

Figure 5. Densities of sea water and aqueous solutions of ammonium bicarbonate at 20° C.

Figure 6. Densities of ammonium bicarbonate-normal sea water solutions at 20° C.

The densities of sea water, normal, diluted, and concentrated, and of aqueous solutions of ammonium bicarbonate are given as a function of concentration in Figure 5. Figure 6 gives the densities of solutions of ammonium bicarbonate made up in sea water of varying salinity. All of these density measurements were made at 20° C. by means of a pycnometer. 

The density of a substance is the weight per unit volume of the substance. Density of a substance is also known as its specific gravity. The density of water is 1. It is used as the standard to find out the density of other substances. The density of sea water is 1.025. 

A method of producing drinkable water from salt water is reverse osmosis, in which a pressure just in excess of the osmotic pressure is applied to the solution in order to reverse the flow of the solvent (H2O). In principle, what pressure would be required to produce pure water from sea water at 25°C Assume that sea water has a density of 1.021 g/mLand can be considered equivalent to 3.00% by weight NaCl, which is 100% ionized. Express your answer in atm, kPa, and psi. 

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