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chapter 3 bio

Terms in this set (48)

______________ is the only common substance to exist in the natural environment in all three physical states of matter
water
Water's unique emergent properties help make earth suitable for ___________
life
The structure of the water molecule allows it to ________ with other molecules
interact
In the water molecule, the electrons of the __________________ spend more time near the oxygen than the hydrogen
polar covalent bonds
the water molecule is thus a ________________
polar molecule (the overall charge is unevenly distributed)
________________ allows water molecules to form hydrogen bonds with eachother
polarity
Four of water's properties that facilitate an environment for life are
-cohesive behavior
-ability to moderate temperature
-expansion upon freezing
-versatility as solvent
Collectively, hydrogen bonds hold water molecules together, a phenomenon called _____________
cohesion
_________________ is an attraction between different substances, for example, between water and plant cell walls
adhesion
________________________ is a measure of how difficult it is to break the surface of a liquid
surface tension
why does water have an unusually high surface tension?
it is due to hydrogen bonding between the molecules at the air-water interface and to the water below
kinetic energy
the energy of motion
thermal energy
the kinetic energy associated with random motion of atoms or molecules
________________ represents the average kinetic energy of the molecules in a body of matter
temperature
thermal energy in transfer from one body of matter to another is defined as __________
heat
a ______________ is the amount of heat required to raise the temperature of 1 g of water by 1 degree C
calorie (cal)
the "calories" on food packages are actually __________________
kilocalories (kcal) 1kcal= 1,000 cal
the __________ is another unit of energy
Joule (J) 1 J=0.239 cal, 1cal= 4.184 J
the _________________ of a substance is the amount of heat that must be absorbed or lost for 1 g of that substance to change its temperature by 1 degree C
specific heat
the specific heat of water is __________
1 cal/g/°C
why does water resist changing its temperature ?
because of its high specific heat
Why does water have a high specific heat?
because of hydrogen bonding. Heat is absorbed when hydrogen bonds break and heat is released when hydrogen bonds form
_________________ is the heat a liquid must absorb for 1 g to be converted to gas
heat of vaporization
as a liquid evaporates, its remaining surface cools, a process called ___________________
evaporative cooling
what does evaporative cooling of water do?
helps stabilize temperatures in organisms and bodies of water
where does water reach its greatest density?
4 degrees Celsius
a ___________ is a liquid that is a completely homogeneous mixture of substances
solution
the _____________ is the dissolving agent of a solution
solvent
the ___________ is the substance that is dissolved
solute
An __________ is one in which water is the solvent
aqueous solution
water is a versatile solvent due to its _______________
polarity
when an ionic compound is dissolved in water, each ion is surrounded by a sphere of water molecules called a __________________
hydration shell
a __________ substance is one that has an affinity for water
hydrophilic
a _______________ substance is one that does not have an affinity for water
hydrophobic
what is molecular mass?
The sum of the masses of all the atoms in a molecule
1 mole =
6.02 x 10^23
________________ is the number of moles of solute per liter of solution
molarity (M)
the hydrogen atom leaves its electron behind and is transferred as a proton, or __________________
hydrogen ion (H+)
the molecule that lost the proton is now a _______________
hydroxide ion (OH-)
The molecule with the extra proton is now a __________________, though it is often represented as H+
hydronium ion
biologists use the ________ scale to describe whether a solution is acidic or basic (the opposite of acidic)
pH
an ______________ is a substance that increases the H+ concentration of a solution
acid
a __________ is a substance that reduces the H+ concentration of a solution
base
the ___________ of a solution is defined by the negative logarithm of H+ concentration, written as pH=-log[H+]
pH
_____________ are substances that minimize changes in concentrations of H+ and OH- in a solution
buffers
CO2 dissolved in seawater forms carbonic acid; this process is called _________________
ocean acidification
aqueous solution
a solution in which water is the solvent
Because organisms are made primarily of water, they resist rapid temperature changes. This useful quality is based on water's _____.
high specific heat
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