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water molecules are held together by
polar covalent bonds
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water is thought of as a universal
solvent
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because oxygen greedily holds its electrons, they get pulled to the "oxygen" side and there is a relative positive charge on oxygen and a relative negative charge on hydrogen.... what is this an example of (partial)
dipole
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water is ________ dense as a solid than a liquid
less; ice floats.
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________ bonds hold the two complimentary strands of DNA together
Hydrogen
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Ionic bonds are found in _______ and _______
teeth; bones
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Covalent bonds form most important bonds in _______ and in the ________ of DNA and RNA molecules.
Proteins; backbones
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when water is split to form H+ and OH- ions, the resulting charged ions contribute to
pH
-
Oriented water molecules are
hydration shells
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define surface tension
a property that results from the cohesion of molecules to each other.
-
detergents are
surfactants
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_________ secreted by cells in the lung reduce surface tension.
Surfactant
-
One end of a surfactant molecule likes grease, the other end likes
water
-
without surfactant lungs cannot
inflate
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define capillary action
results from the cohesive forces within the liquid and the adhesive forces between the liquid and the walls. If the adhesive force between the wall of the container and water is greater than the adhesive force between water molecules, then the water will "climb" the walls of the tube.
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In a solution, a substance is called the _______ dissolves another substance called the ________
solvent; solute
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Usually there is more ________ than solute
solvent
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In human biology, the solvent is always
water
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If you dissolve sugar in water and it forms a sugar solution. What is the solvent and what is the solute
- Solvent water
- solute sugar
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define a mole
is just a convenient way of counting large numbers of small things
-
-
What is Avagadro's number
6.02 x 1023
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define colloids
like solutions, except the particles are large enough to scatter light.
-
define emulsion
is a colloid where all components are liquid
-
define suspension
the particles are even larger than colloid, and these settle to the bottome of a container given time
-
define acid
a substance that dissolves in water to form one or more H+ ions and one or more anions
-
define base
is a substance that dissolves in water to form one or more OH- ions and one or more cations
-
define salt
is a substance that dissolves into ions. it does not form either H+ ions or OH- ions.... examples NaCl, KCl, CaCO3
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acids in the human body include
- gastric juice
- vaginal fluid
- urine (most of the time)
- saliva
-
bases in the human body include
- urine (only rarely)
- blood
- semen
- cerebrospinal fluid
- pancreatic juice
- bile
-
the most important buffer system in human biology is the
carbonic acid-bicarbonate buffer system
-
define pH
negative logarithm of the hydrogen ion concentration
-log[H+]
-
weak acids and weak bases are important components of a special type of solutions called
a buffer
-
define strong acid
practically all HCl molecules break apart into H+ and Cl- ions when we put HCl into water.
-
what are commonly encountered strong acids
Hydrochloric acid HCl
Sulfuric acid H2SO4
Nitric acid HNO3
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define strong base
because almost all KOH molecules break apart into K+ and OH- when we dissolve KOH in water
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