X1014259743-00005-00951</DOCNO> Lecture 7 -- Physical properties of seawater II (Chapter 4) Lecture 7 -- Physical Properties of Seawater II Water molecules dipole structure Change of state latent heat of vaporization = 540 calories 1 calorie = heat required to raise temp of 1 gm liquid water by 1 deg C latent heat of fusion = 80 calories Power of dipole structure and hydrogen bonds liquid water molecules form clusters hydrogen bonds form between molecules in the cluster Anomalous character of water huge range of temperatures for which water is liquid no other molecule has such a large range of temperatures for its liquid state CH4, melting point = -182 deg C, boiling point = -162 deg C, range = 20 deg NH3, mp = -78 deg C, bp = -33 deg C, range = 45 deg H20, mp = 0 deg C, bp = 100 deg C, range = 100 deg H2S, mp = -86 deg C, bp = -62 deg C, range = 24 deg Expansion/contraction ice is less dense than liquid water for fixed mass, water volume decreases as temperature increases from 0 to 4 deg C that is, density of pure water increases with temperature from 0 to 4 deg C density of pure water decreases as temperature increases above 4 deg C Density of pure water and spring overturn in lakes freezing point at 0 degrees centigrade maximum density at 4 degrees centigrade (unlike most liquids -- largely because of the strong dipolar nature of the molecule) explains why lakes overturn in the spring after the winter ice melts summer: warm water overlies more dense cold water fall: cooling near surface gives rise to water of maximum density at 4 deg C winter: water colder than 4 deg C remains at surface (less dense than deeper water at 4 deg C), and ice layer forms at surface spring: ice melts and density decreases as it warms until 4 deg C, at which point the maximum density is at the surface.
(water volume; decreases; unlike most liquids -- largely because of the strong dipolar nature of the molecule) Context(water volume decreases,List([940, 962))):(24 deg Expansion/contraction ice; is; less dense than liquid water for fixed mass) (than 4 deg C; remains less dense; at surface) Context(than 4 deg C remains less dense,List([1586, 1629))):(cooling near surface; gives; rise; to water of maximum density; T:at 4 deg C winter) Context(cooling near surface gives than 4 deg C remains less dense,List([1494, 1629))):(Lecture 7; explains; why lakes overturn in the spring after the winter ice melts summer: warm water overlies more dense cold water fall) Context(Lecture 7 explains cooling near surface gives than 4 deg C remains less dense,List([32, 1629))):(0 degrees; centigrade; ) Context(Lecture 7 explains cooling near surface gives than 4 deg C remains less dense,List([32, 1629))):(warm water; overlies; more dense cold water fall) (II (Chapter 4) Lecture 7 -- Physical Properties of Seawater II Water molecules dipole structure; Change; 540 calories 1 calorie = heat required to raise temp of 1 gm liquid water by 1 deg C latent heat of fusion) (temperatures; is liquid; T:no other molecule) (ice layer forms at surface spring: ice melts and density; decreases; T:as it warms until 4 deg C) (it; warms; T:until 4 deg C) (temperature increases above 4 deg C Density of pure water and spring; overturn; L:in lakes freezing point at 0 degrees centigrade maximum density at 4 degrees centigrade) (the winter ice; melts; summer) (4 deg C; is; ) (the maximum density; is; at the surface; L:4 deg C; T:at which point) (lakes; overturn; T:after the winter ice melts summer)
water volume decreases,List([940, 962)) than 4 deg C remains less dense,List([1586, 1629)) cooling near surface gives than 4 deg C remains less dense,List([1494, 1629)) Lecture 7 explains cooling near surface gives than 4 deg C remains less dense,List([32, 1629)) Lecture 7 explains cooling near surface gives than 4 deg C remains less dense,List([32, 1629))
water volume 24 deg Expansion/contraction ice than 4 deg C cooling near surface Lecture 7 0 degrees warm water II (Chapter 4) Lecture 7 -- Physical Properties of Seawater II Water molecules dipole structure temperatures ice layer forms at surface spring: ice melts and density it temperature increases above 4 deg C Density of pure water and spring the winter ice 4 deg C the maximum density lakes
decreases is remains less dense gives explains centigrade overlies Change is liquid decreases warms overturn melts is is overturn
unlike most liquids -- largely because of the strong dipolar nature of the molecule
less dense than liquid water for fixed mass
at surface
rise to water of maximum density T:at 4 deg C winter
why lakes overturn in the spring after the winter ice melts summer: warm water overlies more dense cold water fall
more dense cold water fall
540 calories 1 calorie = heat required to raise temp of 1 gm liquid water by 1 deg C latent heat of fusion
T:no other molecule
T:as it warms until 4 deg C
T:until 4 deg C
L:in lakes freezing point at 0 degrees centigrade maximum density at 4 degrees centigrade
summer
at the surface L:4 deg C T:at which point
T:after the winter ice melts summer