Properties of Water

Marine Science Notes Series

Water Molecule and Bonding Forces

I. London Forces: Intramolecular a) Covalent Bonds: sharing of electrons

between Hydrogen and Oxygen

b) Van der Waals – forces within the water molecule

c) Hydrogen Bonds – keeping a network of water molecules together (~105 0 angle)

http://en.wikipedia.org/wiki/Image:Wasserstoffbr%C3%BCckenbindungen_des_Wasser.png

Energy & Water• Heat Values are measured in calories and

joules. a) a calorie is the amount of heat energy needed to raise the temperature of 1 gram of water by 10C

This is sometimes called specific heatb) There are energy values when water changes state from a solid to a liquid to a gas(Latent Heat of… Fusion and of Vaporization)c) Temperature is an indirect function of heat energy

F= 9/5 C + 32C = 5/9 (F – 32)

Specific Heat of Salt Water?

• We will calculate the specific heat of salt water, but will see how accurate we are by determining the specific heat of a known metal

Heat Loss or Gain = m (Cp) T

Cp = Specific Heat

Special Properties of Watera) Water can break salts down into ions

(which are charged particles) Cations are positive ionsAnions are negative ions

b) Cohesion – This holds a water molecule together as a “body”

c) Adhesion – the ability of water to bond with other molecules

d) Viscosity – the ability of a liquid to flowe) Density – varies with temperature*

Seawater

• The density of seawater at 4 oC is approximately 1.0278 g/cm3

• The freezing point of seawater is -1.33 oC

• Open ocean water has a salinity of 35 g/kg

Eleven Major Constituents

• Chloride• Sulfate• Bromide• Bicarbonate• Fluoride

• Boron• Strontium• Calcium• Potassium• Magnesium• Sodium

Residence Time of Chloride is 80 million years

Residence Time of Sodium is 60 million years

Light and Seawater• Visible light ranges from 350 to 720 nm as

part of an electromagnetic light visibl emission

-In the first 1 meter – 60% of light is absorbed

-In the first 11 meters, 80% of light is absorbed

-Below 1000 m, no light penetrates

Attenuation

Nature Reviews Microbiology 2007

Gases in water

• Solubility is determined by – Temperature– Salinity – Density

It is measured in mg/L or ppm. The understood gases are Oxygen and Carbon dioxide