Biology Chp 3 Flashcards
Four Emergent Properties of Water
chp 3
Cohesion, moderation of temp, expansion upon freezing, versatility as a solvent
Water is the only substance to exist in natural environment in all three physical states of matter
Polar covalent bonds
chp 3
e- spend more time closer to the higher electronegative atoms
Polar molecule
chp 3
unequal sharing of e-, overall charge unequally distributed
Cohesion
chp 3
hydrogen bonds hold a substance together.
- Contributes to the transport of water and dissolved nutrients in plants
Surface tension
chp 3
result of cohesion. a measure of how difficult it is to stretch or break the surface of a liquid
Adhesion
chp 3
the clinging of one substance to another.
- Contributes to transport of water and dissolved nutrients in plants
Kinetic Energy
chp 3
the energy of motion
atoms and molecules have kinetic energy
Thermal energy
chp 3
the kinetic energy accociated with the random movement of atoms or molecules.
- reflects total kinetic energy -> depends on matter’s volume
Temperature
chp 3
represents the average kinetic energy of the molecules in a body of matter, regardless of volume
passes from warmer to cooler object
Heat
chp 3
Thermal energy in transfer from one body of matter to another
Calorie (cal)
chp 3
the amount of heat it takes to raise the temperature of 1g of water by 1° C
Also the amount of heat water releases when lowering in temp
Kilocalorie (1,000cal)
chp 3
quantity of heat required to raise the temp of 1kg of water by 1° C
Joule (J)
chp 3
1 J = 0.239cal ; 1cal = 4.184 J
Specific Heat
chp 3
the amount of heat that must be absorbed or lost for 1g of that substance to change its temp by 1° C.
- HIgher specific heat means less temperature change
The specific heat of H20 = 1cal/(g°C)
Vaporization/Evaporation
chp 3
when molecules move fast enough to overcome attractions keeping them together
higher heat = greater evaporation
Heat of vaporization
chp 3
quantity of heat a liquid must absorb for 1g of it to be converted from the liquid to the gaseous state
Evaporative cooling
chp 3
as a liquid evaporates, the surface of the liwuid that remains behind cools down
Floating Ice on Liquid Water
chp 3
H20 is less dense as a solid
- due to h-bonding
- floating ice allows for marine life
Solution
chp 3
completely homogenous mixture of 2 or more substances
Solvent
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dissolving agent in a solution
Aqueous solution
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solution in which solute is dissolved in water
Solute
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substance that is dissolved
Hydration shell
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sphere of h20 molecules around each dissolved ion
Hydrophilic
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any substance that has an affinity for water
Hydrophobic
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substances that repel H2O
major ingredients in cell membranes
Molecular mass
chp 3
sum of the masses of all the atoms in a molecule
mole (mol)
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unit used to measure substances.
- sometimes called molar mass
Molarity
chp 3
the number of moles of solute per liter of solution
Hydroxide Ion (OH-)
chp 3
The result of a water molecule losing a proton (H+). has a negative charge
Hydronium Ion
chp 3
The result of the proton from another water molecule binding to another H20 molecule, making it H3O+
H+ often represents H3O+
Dissociation of Water
chp 3
- Statistically rare
- reversible reaction
Acid
chp 3
a substance that increases the hydrogen ion concentration [H+] of a solution
Base
chp 3
a substance that reduces the hydrogen ion concentration of a solution
Neutral Solutions
chp 3
[H+] = [OH-]
Weak Acids
chp 3
acids that reversibly release and accept back hydrogen ions
Carbonic Acid
pH of any aqueous solution
chp 3
In any aqueous solution at 25° C, the product of the H+ and OH- concentrations is constant at 10^-14
Can be written as [H+][OH-] = 10^-14
[H+] = 10^-7
[OH-] = 10^-7
brackets indicate molar concentration
pH
chp 3
the negative logarithim(base 10) of the H+ concentration.
- Higher pH is more basic while lower pH is more acidic
pH = -log[H+]
internal pH of most living cells must stay close to pH=7
Buffers
chp 3
A substance that minimizes changes in the concentrations of H+ and OH- in a solution
- accepts hydrogen ions from the solution when they are in excess and donates hydrogen ions when they have been depleted
Most contain a weak acid and it’s corresponding base
One of the buffers that contributes to pH stability in blood is carbonic acid (H2CO3) which is formed when CO2 reacts with H2O in blood plasma
Ocean acidification
chp 3
when CO3 dissolves in dea water, reacting with H2O to form carbonic acid, which lowers ocean pH
