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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