Chapter 3 Flashcards by Sydney Hayes

Water

-polar molecule, opposite ends have opposite charges
-polarity allows water molecules to form hydrogen bonds with each other

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4 water properties that allow environment for life on earth

-cohesive behavior
-ability to moderate temperature
-expansion upon freezing
-versatility as a solvent

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Cohesion

-hydrogen bonds hold water molecules together
-helps transport of water against gravity in plants

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Adhesion

attraction between different substances

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Surface tension

-measure of how hard it is to break the surface of a liquid
-related to cohesion- top of water is arranged through hydrogen bonds

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Moderation of temperature

-absorbs heat from warmer air and releases stored heat to cooler air
-can absorb or release a large amount of heat with only slight change in its own temperature

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Kinetic energy

-in anything that moves
E=mv^2/2
e=random movement of atoms=thermal energy
m=mass
v^2= speed of movement

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Temperature

average kinetic energy of body of matter

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Heat

thermal energy transferred from one body of matter to another

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Total thermal energy

proportional to the amount (mass) of the matter

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Temperature measurements

C
calorie(cal)= amount of heat required to raise the temp of 1g by 1C
1kcal=1000 cal
Joule(J)=0.239cal
1cal=4.184J

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Specific heat

the amount of heat that must be absorbed or lost for 1g of substance to change its temp by 1C
-water resists changing its temp because of high specific heat because of hydrogen bonding (absorbs heat to break hydrogen bonds, releases heat when hydrogen bonds form)

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Evaporation

transformation from liquid to gas

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Heat of vaporization

the heat a liquid must absorb for 1g to be converted to gas

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Evaporative cooling

-as liquid evaporates its remaining surface cools
-helps stabilize temperatures in organisms and bodies of water

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Why ice floats

-hydrogen bonds in ice are more ordered=ice is less dense

Solution

liquid that is a homogeneous mixture of substances

Solvent

the dissolving agent of a solution

Solute

substance that is dissolved

Aqueous solution

one where water is the solvent

Why water is versatile solvent

-polarity, allows it to from hydrogen bonds easily
-dissolves compounds made of non-ionic polar molecules

Hydration shell

sphere of water molecules that surround each ion when an ionic compound is dissolved in water

Hydrophilic

substance that has affinity for water
-usually dissolves

Hydrophobic

substance that does not have affinity for water
-does not mix with water

Chemical reactions depend on

collisions of molecules (concentrations of solutes)

Molecular mass

sum of all masses of all atoms in a molecule

1 mole(mol)

6.02 x10^23 molecules

Molarity

of moles of solute/liter of solution

Hydronium ion

H3O +

Hydroxide ion

OH -

Proton

hydrogen ion (H+)

acid

substance that increases the H+ concentration of a solution -pH values less than 7

Base

substance that reduces the H+ concentration of a solution -pH values greater than 7

[H+][OH-]=

10^-14

concentration in water

[H+]=[OH-]=10^-7

pH=

-log[H+] -each pH change is a 10x change in concentration of H+

Buffers

substances that minimize changes in concentrations of H+ and OH- in solution -consist of weak acid and corresponding base