Test 3 Flashcards
Chapters 7, 8, & 9
exothermic
a process or reaction that gives off heat
change of heat < 0
endothermic
a process or reaction to which heat is added
change of heat > 0
- gases consist of molecules that are in constant, rapid, straight-line motion; different molecules can move at different speeds but the average speed will not change as long as the temperature does not.
- the average kinetic energy of the gas molecules depends only upon the temperature and it is directly proportional to the Kelvin temperature
- gas molecules interact only when they collide with one another, otherwise there are no forces between gas molecules
- gas molecules are very small compared to the distance between gas molecules; a gas is mostly empty space
- the force of gas molecules hitting the sides of its container create a pressure on the sides of the container
NOTE: there are forces fo attraction between the molecules of a real gas
gas to liquid : decrease temperature, decrease volume, increases pressure
The Kinetic - Molecular Theory
pressure definition
the force exerted by the gas on a given area of the container wall divides by that area
=(force)/(area)
pressure units
atmospheres - atm
millimeters of mercury - mmHg
1 atm =
760 mmHg
1 Torr =
1 mmHg
atmospheric pressure definition
the amount of pressure exerted by the weight of the atmosphere above us on a normal day
barometer
measures atmospheric pressure
ideal gas definition
a gas that would behave according to Boyle’s law, Charles’ law, and Gay-Lussac’s law and would follow the ideal gas law exactly (no such thing exists)
ideal gas law
PV=nRT
Boyle’s Law
fixed number of moles at constant temperature increase gas pressure and decrease volume
Charles’ Law
fixed number of moles at constant pressure increase temperature and increase volume; decrease temperature and decrease volume
Gay-Lussac’s Law
fixed number o f moles at constant volume increase temperature and increase pressure; decrease temperature and decrease pressure
P
pressure of gas in atm
V
volume of gas in Liters
n
number of moles of gas
T
temperature of gas in Kelvin degrees
R
constant
=0.08205
(L)(atm)/(mole)(K)
Dalton’s law of Partial Pressures
an ideal mixture of ideal gases each gas exerts a partial pressure that is the same pressure that would exert if it were only 1 gas present
vapor pressure
if a liquid is allowed to evaporate in a closed container the evaporation will eventually stop, the container will have both liquid and gas which was evaporated from liquid; the partial pressure of the gas is referred to as the vapor pressure of a liquid always goes up as the temperature goes up
boiling point
the temperature at which the vapor pressure of the liquid equals the atmospheric pressure
normal boiling point
the temperature at which boiling occurs when atmospheric pressure is 1 atm
melting point
the temperature at which, upon heat, the solid will change to a liquid
freezing point
the temperature at which upon cooling, liquid changes to solid
heat of vaporization
the amount of heat needed to convert 1g of liquid to vapor, given temperature
unit: cal/g
molar heat of vaporization
value is given for 1 mole of liquid unit
kcal/mol
heat of fusion
the amount of heat required to convert 1g of solid into a liquid of the melting point
molar heat of fusion
1 mole of solid unit is
kcal/mole
sublimation
the conversion of a solid directly into a gas without the formation of a liquid (ex. dry ice)
dynamic equilibrium
the amount of a liquid and a gas do not change; there is a constant interchange between liquid and gas in closed container
solution
a homogeneous mixture of 2 or more substances at molecular level
solvent
that which does the dissolving (usually a liquid)
solute
that which is dissolved (liquid, gas, or solid)
concentration
a measure of the amount of solute dissolved in a fixed amount of solvent (%m/v and molarity)
solubility
a measure of the maximum amount of solute that can normally be dissolved in a fixed amount of solvent, at a given temperature
saturated solution
a solution containing the maximum amount of solute that can normally be dissolved in a given amount of solvent
unsaturated solution
a solution which contains an amount of solute less than that required to form a saturate solution
miscible
if 2 liquids will dissolve in one another in any amoutn
immiscible
if 2 liquids will not dissolve in one another
hydrophilic
soluble in water
hydrophobic
not soluble in water
Principles Governing Solubility
attractions between solute molecules are similar in type and strength to attraction between solvent molecules
“like dissolves like”
polar solvents dissolve polar solutes
non polar solvents dissolve non polar solutes
polar substances do no readily form solutions with non polar substances
the effects of pressure on solubility
only when the solute or solvent is a gas
the most important situation involves the solution of a gas in a liquid
as the pressure of the gas increases, its solubility in the liquid increases
doubling the pressure doubles the solubility, doubling the gas pressure allows us to dissolve twice as much gas
percent weight/volume =
(%m/v)=
(mass of the solute in g) / (volume of solution in mL) x 100
do not need to know identity only mass
ALWAYS TRUE: always equal to t eh number of grams of solute in 100.0 mL of solution
molarity =
M
(moles of solute) / (total value of solution in L)
do not need to know identity bc need to know moles
strong electrolyte
a substance that dissociate completely not ions when dissolved(in H2O)
includes strong acids, strong bases, and all ionic compounds
weak electrolyte
a molecular substance such that most of the dissolved molecules do not dissociate
includes: weak acids, weak bases, and water itself
non electrolyte
a substance that does not dissociate at all
sugars, dextrose
colligative properties
solution properties that depend on the concentration of solute particles but not upon their identity
osmolarity definition
(moles of solute particles)/(volume of solution in L)
osmol/L or osm/L
goes up as solution volume goes down
goes down as solution volume goes up
osmoles
number of moles of solute particles
four important colligate properties
vapor pressure lowering
freezing point depression
boiling point elevation
osmosis
osmosis
2 solutions which are separated by a membrane though which small solvent molecules(water) can pass but through which solute particles cannot pass
traveling form the solution f lower osmolarity to the solution of high osmolarity
osmolarity calculation for 1 solute
(molarity) x (# of solute particles per formula unit)
flow of osmolarity
water flows in the direction that ten to make the osmolarity the same on both sides
solution flows from hypo-osmotic solution to the hyper-osmotic solution
osmotic membrane definition
water can pass through but solute particles cannot
terms isotonic, hypertonic, and hypotonic when…
comparing a given solution to. physiological solution
physiological solution
a solution with a milliosmolarity in the range of 280-310 mosmol/:; osmolarity of blood and cells falls within this range
IV solutions are described using these terms
milliosmolarity =
osmolarity x 1000
hypotonic
a solution with osmolarity less that that of a physiological solution
isotonic
a solution with osmolarity equal to that of a physiological solution
hypertonic
a solution with osmolarity greater than that of a physiological solution
