COMPARISON WITH OTHER SUBSTANCES
IMPORTANCE IN THE OCEAN
|Heat capacity & thermal conductivity||Highest of all liquids and solids except liquid ammonia||Prevents extreme temperature ranges encourages heat transfer|
|Latent heat of fusion||Highest of all except ammonia||Acts as a thermostat at freezing point|
|Latent heat of vaporization||Highest of all substances||Important in heat and water transfers to the atmosphere|
|Thermal expansion||maximum density is 4o C. for pure water, lower with increasing salinity||Allows fresher water near freezing to rise to surface, ice floats|
|Surface tension||Highest of all liquids except mercury||Controls drop formation & behavior, cause of capillary waves|
|Dissolving power||Dissolves more substances in greater quantities than any other liquid||Makes nutrients of all kinds available to organisms|
|Transparency||Relatively great||Most transparent in visible range, thus allows underwater photosynthesis|
|Freezing & boiling point||Much higher than similar substances||Allows most water to exist as a liquid|
ENERGY TO BREAK (Kcal)
|Nonpolar covalent||Equal sharing of electrons||100s||O2, H2|
|Polar covalent||Polar covalent||~100s||H2O, NH3|
|Ionic||Redistribution of electrons||10s||NaCl, KCl|
|Hydrogen||Attraction of partial charges||4.5||H2O with itself and many solutes|
|Molecules more tightly packed||Molecules less tightly packed|
|Some molecules form clusters, others are free||All molecules structures in a regular lattice|
|All molecules structures in a regular lattice||Solute molecules are excluded|
Most water molecules are free, not locked in clusters.
Clusters are very short lived (less than one-millionth of a microsecond).
Water is less structured at higher temperatures.
At pressures over 1000 atmospheres all structure is lost, because structured regions are less dense.
No structure is present in water vapor.
Adding heat to water raises its temperature within its current state.
Adding heat to water existing at a state change boundary results in no temperature change, only the breaking of hydrogen bonds.
Defined as the amount of salt in the water.
Expressed as parts per thousand, written .
Average salinity is 35 %°.
Measured using electrical conductivity.
Vapor pressure decreased by increased salinity.
Increased salinity increases osmotic pressure.
Defined as the resistance of a liquid to flow.
Especially important to very small organisms near the surface.
Viscosity increases with greater salinity and viscosity decreases with higher temperature.
Different ions have different effects on viscosity.
Defined as mass per unit volume.
Increasing salinity and/or pressure increases density.
Increasing temperature decreases density.
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