120207-T-WaterProperties-Water-Heat.R

120207-T-WaterProperties-Water-Heat.R - 2/12/12 THE ATOM...

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Unformatted text preview: 2/12/12 THE ATOM Number of protons distinguishes one element from another. Protons = Electrons Electrons in "shells" Atomic Structure Atomic Structure HOW BIG ARE THESE THINGS? Kroger 1 2/12/12 Atoms Neutral atoms have the same number of protons and electrons. Ions are charged atoms. -cations have more protons than electrons and are positively charged -anions have more electrons than protons and are negatively charged ISOTOPES DEUTERIUM TRITIUM Elements There are 90 naturally occurring elements. Only 12 elements are found in living organisms in substantial amounts. Four elements make up 96.3% of human body weight: - carbon, hydrogen, oxygen, nitrogen Elements There are 90 naturally occurring elements. Only 12 elements are found in living organisms in substantial amounts. Four elements make up 96.3% of human body weight: - carbon, hydrogen, oxygen, nitrogen Elements There are 90 naturally occurring elements. Only 12 elements are found in living organisms in substantial amounts. Four elements make up 96.3% of human body weight: - carbon, hydrogen, oxygen, nitrogen Elements There are 90 naturally occurring elements. Only 12 elements are found in living organisms in substantial amounts. Four elements make up 96.3% of human body weight: - carbon, hydrogen, oxygen, nitrogen 2 2/12/12 Elements There are 90 naturally occurring elements. Only 12 elements are found in living organisms in substantial amounts. Four elements make up 96.3% of human body weight: - carbon, hydrogen, oxygen, nitrogen Stability is enhanced if shells are complete WATER MOLECULE! WATER MOLECULE! VERY STABLE MOLECULE Text Text covalent bonds covalent bonds 3 2/12/12 Hydrogen Bonds water partially sticks to itself extra heat to separate the water = high heat of boiling (evaporation) = high heat of melting (ice-water) Hydrogen Bonds water partially sticks to itself! cohesion: water molecules stick to other water molecules by hydrogen bonding cohesion: water molecules stick to other water molecules by hydrogen bonding Manning, 1997! Hydrogen Bonds adhesion: water molecules stick to other polar molecules or polar surfaces by hydrogen bonding capillary "force"! adhesion: water molecules stick to other polar molecules or polar surfaces by hydrogen bonding! 4 2/12/12 What happens when "HEAT" (calories) is added to water What happens when "HEAT" (calories) is added to water water warms water molecules move faster (vibrate, What happens when "HEAT" (calories) is added to water water warms water molecules move faster (vibrate, What happens when "HEAT" (calories) is added to water water warms water molecules move faster (vibrate, rotate, 5 2/12/12 What happens when "HEAT" (calories) is added to water water warms water molecules move faster (vibrate, rotate, What happens when "HEAT" (calories) is added to water water warms water molecules move faster (vibrate, rotate, translate ) What happens when "HEAT" (calories) is added to water water warms water molecules move faster (vibrate, rotate, translate ) What happens when "HEAT" (calories) is added to water vibration, rotation, translation is resisted by the hydrogen bonding of water. It takes a lot of added heat to raise the temperature of water What happens when "HEAT" (calories) is added to water vibration, rotation, translation is resisted by the hydrogen bonding of water. It takes a lot of added heat to raise the temperature of water 1 cal / 1 deg for each gram What happens when "HEAT" (calories) is added to water T EA H LE ns is d vibration, rotation, translation e B resisted by the hydrogen bonding of SI se water. N SE n be It takes a lot of added heat to raise the ca temperature of water 1 cal / 1 deg for each gram 6 2/12/12 What happens when "HEAT" (calories) is added to water vibration, rotation, translation is resisted by the hydrogen bonding of water. W Y? H Heat Capacity is a measure of the heat required to raise the temperature of 1g of a substance by 1C. It takes a lot of added heat to raise the temperature of water 1 cal / 1 deg for each gram LIQUID CLUSTERS Water Clusters: number of linked water molecules Added calories break hydrogen bonds of clusters. Heat Capacity: Capacity to hold heat. 7 2/12/12 Heat Capacity: Capacity to hold heat. How many calories (a measure of heat, energy) must be added to raise the temperature of one gram of a substance by one degree? If a lot of heat (lot of calories) are needed to raise the temperature of one gram of a substance by one degree, then that substance can really "hold" heat. It has a high heat capacity. If the temperature rises rapidly by adding only a small amount of heat (calories), then that substance has a low heat capacity. Latent Heat: Hidden heat. How many calories must be added to change one gram of a substance from one form to another - e.g. ice to water or water to vapor? It all seems hidden to me ! Water molecules with greater energy are more likely to "escape" the H bonds http://ed101.bu.edu/StudentDoc/current/ED101fa10/vebado/Content_1.html Evaporation removes energetic molecules. Evaporation is a cooling process. http://ed101.bu.edu/StudentDoc/current/ED101fa10/vebado/Content_1.html 8 2/12/12 For water to evaporate, heat must be added to water in the liquid state. After water reaches 100C, an input of 540 cal/gram is required to break the hydrogen bonds and allow evaporation. The amount of energy required to break the bonds is termed the latent heat of vaporization. Water has the highest latent heat of vaporization of any known substance. http://ed101.bu.edu/StudentDoc/current/ED101fa10/vebado/Content_1.html 9 2/12/12 End Tuesday 2012-February 7 http://ed101.bu.edu/StudentDoc/current/ED101fa10/vebado/Content_1.html 10 ...
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This note was uploaded on 02/15/2012 for the course GLG 244 taught by Professor Sikorski during the Spring '05 term at Miami University.

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