WATER

• Most abundant liquid on the earth• Chemical Formula: H2O

• Density: 1 g/mL• Freezing Point: 0°C• Boiling Point: 100°C• One of the only substances whose solid form

floats in its liquid form (Ice)

Rime of the Ancient Mariner by Samuel Coleridge

“Water, water, everywhere, And all the boards did shrink;

Water, water everywhere, Nor any drop to drink.”

FYI: Water• Appx 70% of the human body is water• The average human can drink about 3

gallons/12L of water a day• The total amount of water on the earth is 326

cubic million miles of water• More fresh water is stored underground in

aquifers than above ground• Drinking too much water too fast can lead to

water intoxication, which causes the sodium in the blood to be diluted and causes an imbalance in the brain.

Fun Facts about Water

CHARACTERISTICS OF WATER

• Polar:

• Water is polar due to the high electronegativity of the oxygen atom. This causes the shared electrons to be closer to the oxygen atom, thus creating a polar bond. Thus the oxygen atom becomes slightly negative and the hydrogen atoms become slightly positive. (creating “poles”)

Bent Shape

• The bent shape of the water molecule is what actually makes water polar.

• The 2 lone pairs of electrons on oxygen and the 2 hydrogen atoms push as far apart as possible causing the water molecule to take on a bent shape. (104 degree bond angle between the H’s)

• What makes water polar?

High Surface Tension

• Surface Tension:• auf Deutsch: Wasserüberflaschungspannung• Inward force that tends to minimize the

surface area of a liquid• Liquids with a high surface tension tend to

form spherical droplets• Surfactant: decreases a liquids surface

tension: ex: soap

Cohesion/Adhesion/Surface Tension

Water: Too Stick or Not to Stick

Low Vapor Pressure

• Vapor Pressure: • Caused by molecules that escape the surface

of a liquid and enter the gas phase (in a closed container)

• vapor pressure

High Specific Heat Capacity

• Amount of energy (Joules) required to raise the temperature of 1 g of water 1°C

• Specific heat for water is: 4.184 J g °C

Advantages of a high specific heat:

• Helps prevent bodies of water from evaporating

• Helps prevent our bodies from burning up on the inside

Assorted Specific HeatsSubstance Specific Heat J/g C

Aluminum 0.901

Copper 0.384

Iron 0.449

Sand 0.835

Water 4.184

High Heat of Vaporization

• Heat of Vaporization: the amount of energy needed to convert 1g of a substance from a liquid to a gas at the boiling point

High Boiling Point

• Boiling Point: temperature at which the vapor pressure of a liquid is just equal to the external pressure on the liquid

• The higher the altitude, the lower the temperature at which water boils.

• EX: Water boils at 72°C on Mt. Everest• Pressure cookers can cook food at a

temperature of 120°C therefore decreasing cooking time by 1/3.

Universal Solvent

• Water can dissolve many substances, including metals (turning iron into rust)

• Solvent: substance doing the dissolving• Solute: substance being dissolved• EX: salt water– Water is the solvent– Salt is the solute

Likes dissolve Likes

• Since water is polar, has a positive and negative end, it can dissolve other substances that are polar.

• Water can also dissolve ionic compounds, since they are made up of + and – ions

• Polar substances cannot dissolve nonpolar substances. (nonpolar, do not have a positive and negative end)

Density

• Steve Spangler: 7 Layer Density Column