Three States of Matter(Three Phases of Matter)

Solids, Liquids, and Gases

Outline for Solids, Liquids, and Gases

Micro:

Melting Point Temperature of Chocolate Mixtures

Thermodynamic analysis

Trends in the Properties of the Three States of Matter

More trends in the properties of the Three States of Matter

Properties of Liquids (Viscosity and Surface Tension)

Further properties of liquids (Surface tension & meniscus)

Critical temperature and Refractive Index

Heat of fusion, Heat of Vaporization, and Boiling Point Temperature

Vapor Pressure

Vapor pressure and boiling chips

Water abundant and stable

page 153 top, 7th Ed., 2010

Color of water

From underwater, looking upIn any pool having a white bottom, if more than 3 or 4 feet deep, the water will appear noticeably blue, not colorless.

Water structure and its polarity

Due to its two lone pairs (unshared electron pairs) and its two bonding pairs, the water molecule has a bent shape derived from a tetrahedron. That bent shape causes water to be polar, so it attracts other polar molecules.

An electrostatically- charged rod deflects

water

• A positively-charged rod attracts the stream of polar molecules.

• Surprisingly, a negatively charged rod also attracts a stream (because the water molecules rotate).

Polarity of Water

Desert has little water and thus drastic temperature changes

Water’s Temperature Range

as a Liquid• The temperature range that

water remains a liquid is rather large compared to related molecules.

Water relatives(Hydrides of

congeners, i.e., related elements)

Hydrides of chalcogens

[stinkogens]Group VIA

Melting points & Boiling Points of compounds related to water(hydrides of similar groups).

Note the hydrides of F, O, and N are dramatically out of line due to their Hydrogen “bonding”.

Ice has a regular arrangement using four Hydrogen “bonds” to each water molecule.

This open network leaves large empty spaces, so ice is less dense than liquid water.

Solid benzene sinks in liquid benzene (the usual),but ice floats in liquid water (at left).

Heat involved (per gram) in the Phase Changes of Water

Surface tension is used by some insects to float on water.

Surface tension & meniscus combine to make “capillary action”Meniscus (Greek means little crescent) is due to the liquid’s adhesion to the glass being

greater than the liquid’s cohesion to itself. So, the liquid creeps up at the surface near the glass. The surface tension tries to keep the minimum surface area so the meniscus rises.

Forces in capillary action & meniscus

Surface tension explanationMolecules in interior of the liquid are surrounded by attractive forces, but molecules in the surface layer have only attractions

to below. So, it is as if there is a skin having a strong tendency to make a minimum surface area.

Reduce surface tension by adding surfactant (soap or detergent).

Acute angle

Obtuse angle

surface

surface

Water beads on newly-waxed car

Spherical water droplets on new Petri dish lid

Water shape when dripping from faucet (Hydrodynamics)

Summary of unusual properties of water

p. 153, 7th Ed.

Maximum density of liquid water is at 4°C

Temp. ofmaximumdensity

page 154 top

Temperatures in a lake

page 154 bottom, 7th Ed.

Ice fishing

Hydrologic cycle (Convection on a grand scale)The energy is provided by the sun, but the cycle is also driven by the

rising of the light water vapor molecule. Since more evaporation occurs near the equator and condensation occurs

more near the poles, this causes wind, weather, storms, and runoff.

Cloud (and precipitation) formation at fronts and at mountains.

Glacier National Park

“Rain shadow” on the East side of the continental divide

Snowflake

Snowflake shapes

Snow Crystals book

Freeze-thaw volume change

• Water leaks through cracks in pavement.

• Freezing causes expansion and more breaking of pavement.

• Thaw and drainage of liquid water causes an unsupported hole which is further crumbled by traffic.

Barnard Glacier, Mt. Mc Kinley, Alaskabefore 1969

Ice regelation, Wire cuts but refreezes behind cut

Ice skating“Snow-making” machine

Bob Widing cross-country skiing,

February, 1976

Bob takes a snow sample.Note the hand-print from his statistically-determined sample.

Ban DHMO!

• A parody of environmental extremism.

• http://descy.50megs.com/descy/webcred/webcred/dhmo.html

• http://www.dhmo.org/

• http://www.dhmo.org/facts.html