Test 3 – Chemistry Test Answers – Flashcards
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| properties of gas |
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| expand to fill container and its shape, low density, compressible, mixtures are homogeneous, fluid |
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| structure of gas |
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| composed of particles traveling very fast, move in straight lines until encountering either wall or another particle |
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| kinetic molecular theory |
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| gas particles are constantly moving, attraction between particles is negligible, particle bounce off each other and continue moving (elastic collisions), large empty space between particles, average kinetic energy of particle is directly proportional to kelvin (in temp, in speed) |
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| gas particle pushing |
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| gas molecules constantly in motion, when strike a surface they push that surface, force exerted by gas molecules hitting the entire surface at one instant = pressure that gas is exerting |
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| pressure |
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| the result of the constant collision between atoms or the molecule in a gas and the surfaces around them. pressure = force/area |
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| effects of gas pressure |
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| gas will flow from high to low pressure, if somethings in its pas it will try to push it along (wind) |
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| pressure of gas depends on.. |
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| number of gas particles in a given volume, volume of the container, average speed of the particles (depended on temperature) |
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| air pressure |
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| atmosphere exerts a pressure on everything (average 14.7 psi) |
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| barometer |
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| column of mercury supported by air pressure, force of the air on the surface of the mercury balanced by the pull of gravity on the column of mercury, evangelista torricelli |
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| atmospheric pressure vs altitude |
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| high up means lower atm pressure, rapid changes in pressure causes ears to pop cause of imbalance of pressure |
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| boyle's law |
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| at constant mass and temperature, volume is inversely proportional to pressure, PV=constant |
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| standard conditions |
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| standard pressure = 1.00 atm; standard temperature = 0C=273K; STP= standard temperature and pressure |
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| charles' law |
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| volume is directly proportional to temperature (kelvins) V1/T1=V2/T2 |
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| gay-lussac's law |
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| pressure is directly proportional to temperature (kelvins) P1/T1=P2/T2 |
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| absolute zero |
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| the theoretical temperature at which gas would have zero volume and no pressure 0 Kelvin, never attainable |
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| combined gas law |
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| law that predicts what happens when the volume of a sample of gas when both the pressure and temperature change P1V1/T1=P2V2/T2 |
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| avogadro's law |
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| volume is directly proportional to the number of gas molecules, equal volumes of gases contain equal numbers of molecules, V1/n1=V2/n2 |
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| ideal gas law |
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| use when you have a gas whose condition is changing PV=nRT |
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| molar mass of gas |
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| mass in grams/moles |
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| partial pressure |
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| each gas in the mixture exerts a pressure independent of the other gases in the mixture, sum of all the partial pressures of all the gases in a mixture equal the total pressure |
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| finding partial pressure |
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| multiply the total pressure of the mixture by the fractional composition of the gas |
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| hypoxia |
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| oxygen starvation leads to unconsciousness and death |
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| oxygen toxicity |
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| to much oxygen leads to muscle spasms, tunnel vision, and convulsions |
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| nitrogen narcosis (rapture of the deep) |
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| to much nitrogen |
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| heliox |
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| mixture of helium and oxygen |
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| vapor pressure |
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| partial pressure of the water vapor |
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| molar volume |
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| there is so much empty space between molecules in the gas state that the volume of the gas is not effected by the size of the molecules (under ideal conditions) |
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| properties of liquids |
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| high densities compared to gases, fluid, takes shape of container, keep volume (doesn't expand), cannot be compressed |
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| properties of solids |
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| high densities, nonfluid, keep their own shape and volume, cannot be compressed |
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| crystalline solids |
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| particles arranged in an orderly geometric pattern |
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| amorphous solids |
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| particles do not show a regular geometric pattern over a long time |
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| melting |
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| solid -> liquid, adding heat energy increases kinetic energy of molecules and then overcomes attractive forces holding them. |
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| boiling |
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| liquid -> gas, adding heat increases kinetic energy, soon overcomes attractive forces |
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| surface tension |
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| liquids tend to minimize their surface area and resists penetration. the stronger attractive force between molecules, the larger surface tension |
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| viscosity |
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| the resistance of a liquid's flow because of strong attractive forces |
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| evaporation |
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| the process of molecules of a liquid breaking free from the surface, physical change from liquid -> gas (vapor) |
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| factors effecting rate of evaporation |
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| volatile liquids that evaportate quickly, nonvolatile liquids do not evaporate quickly, increasing SA increases evaporation, increasing temperature increases rate, weaker attractive forces means faster rate |
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| condensation |
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| gas -> liquid, the vapor molecules may eventually bump into and stick to the surface of the contain or get recaptured b the liquid |
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| dynamic equilibrium |
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| opposite processes that occur at the same rate in the same system |
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| vapor pressure |
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| the partial pressure exerted by the vapor, depends on temperature and strength of intermolecular attractions |
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| boiling |
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| the temperature is high enough for molecules in the interior of the liquid to escape |
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| boiling point |
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| the temperature at which the vapor pressure of the liquid is the same as the atmospheric pressure (1 atm) |
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| endothermic |
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| process in which heat flows into a system from the surroundings and causes surroundings to cool (evaporation), solids melting |
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| exothermic |
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| process in which heat flows out of a system into the surroundings and warms the surroundings (condensation), liquids freezing |
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| heat of vaporization |
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| the amount of heat needed to vaporize one mole of a liquid, endothermic, depends on the initial temperature |
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| melting point |
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| you heat a solid, its temperature increases until it reaches the point, latent heat fusion |
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| heat of fusion |
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| the amount of heat needed to melt one mole of a solid |
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| sublimation |
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| a physical change in which the solid form changes directly to the gaseous form, skipping liquid form, endothermic |
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| effect if the strength of intermolecular attractions on properties |
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| stronger attractions take more energy to separate, stronger attractions have higher boiling, melting points, and heat vaporization |
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| why are molecules attracted to each other |
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| +ion and -ion, + - end of polar molecules, larger charge = stronger attraction |
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| dispersion forces (london forces,instantaneous dipoles) |
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| caused by distortion in the electron cloud of one molecule inducing distortion in the electron cloud on another and can lead to a temporary dipole and leads to attractions between molecules |
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| strength of dispersion force |
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| how easily electrons can move, or be polarized, the more electrons and the farther they are from the nuclei, the larger the dipole that can be includes. larger molecules = larger forces |
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| permanent dipoles |
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| a separation of charge resulting from the unequal sharing of electrons between atoms |
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| dipole-dipole attraction |
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| polar molecules have a permanent dipole, the + end of one molecule will be attracted to the - end of another |
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| intermolecular attraction and properties |
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| all molecules are attracted by dispersion forces, polar molecules are attracted by dipole-dipole attractions and have a strong attraction then nonpolar molecules |
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| attractive forces and properties (solubility and miscibility) |
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| like dissolves like, polar molecules dissolve in polar solvents, nonpolar molecules dissolve in nonpolar solvents, if has both polar and nonpolar ten hydrophilic-hydrophobic competition |
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| immiscible liquids |
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| when liquid pentane, a nonpolar substance, is mixed with water, a polar substance, the two liquids separate because they are more attracted to their own kind of molecule than to the other |
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| hydrogen bonding |
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| HF,OH,NH have strong intermolecular bonds, high melting, boiling, and solubility. when it loses the electron the nucleus becomes dishielded, and the exposed proton acts as a very strong center of positive charge |
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| H-bonds vs. chemical bonds |
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| hydrogen bonds are not chemical bonds, hydrogen bonds are attractive forces between molecules, chemical bonds are attractive forces that make molecules |
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| crystalline solids |
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| molecular crystalline solids, ionic crystalline solids, and atomic crystalline solids |
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| ionic crystalline solids |
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| solids whose composite units are formula units, the smallest electrically neutral collection of cations and anions that compose the compound, higher melting point |
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| molecular crystalline solids |
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| solids whose composite units are molecules, low melting |
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| atomic crystalline solids |
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| covalent (effectively one giant molecule), metals (islands of cations in a sea of electrons) |
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| water (unique and important) |
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| all three states on earth, most common solvent, supports life, liquid at room temperature, high boiling point, expands when freeze |
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| solute |
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| the dissolved substance (minority) |
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| solvent |
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| the substance solute dissolved in (majority) |
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| aqueous solutions |
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| solutions in which the solvent is water |
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| soluble |
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| when one substance (solute) dissolves in another (solvent) |
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| insoluble |
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| when one substance does not dissolve in another |
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| solvation |
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| when matericals dissolve, the solvent molecules surround the solvent particles due to the solvent's attractions for the solute |
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| miscible |
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| two liquids that are mutually soluble |
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| solubility |
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| the maximum amount of solute that can be dissolved in a given amount of solvent, concentration |
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| saturated |
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| the maximum amount of solute that will dissolve in that solvent at that temperature |
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| unsaturated |
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| can dissolve more solute |
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| super saturated |
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| holding more solute than they should be able to at that temperature, unstable, precipitate |
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| electrolytes |
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| substances whose aqueous solutions is a conductor of electrivity |
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| strong electrolytes |
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| all the electrolyte molecules are dissociated into ions |
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| nonelectrolytes |
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| none of the molecules are dissociated into ions |
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| weak electrolytes |
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| a small percentage of the molecules are dissociated into ions |
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| solubility of liquid vs temperature |
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| high temp = high sol, low temp = low sol |
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| purifying solids: recrystallization |
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| when a solid precipitates from a solution, crystals of the pure solid form b arranging the particles in a crystal lattice because it reject impurities. make a saturated solution of it at high temperatues and then it cools and the precipitated solid will have much less impurity than before |
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| solubility of gas vs temperature |
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| many gases dissolve in water, solubility of gas in a liquid decreases as the temperature increases |
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| solubility of gas vs pressure |
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| directly proportional to its partial pressure, solubility of a gas in a liquid increases as the pressure increases, high pressure = high solubility |
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| dilute |
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| low amounts of solute per amount of solution |
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| concentrated |
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| high amounts of solute per amount of solution |
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| mass percent |
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| the sum of the masses of solute and solvent, [mass solute (g)/mass of solution (g)] x 100% |
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| preparing a solution |
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| need to know the amount of solution and the concentration of solution you want to prepare |
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| solution concentration molarity |
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| moles of solute per 1 liter of solution, describes how many molecules of solute in each liter of solution, molarity = mole of solute/liters of solution |
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| dilution formula |
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| Concentration x Volume=Concentration x Volume |
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| colligative property |
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| any solution property whose value depends only on the number of dissolved solute particles (freezing point, boiling point, osmotic pressure of a solution) |
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| molarity |
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| moles of solute per 1 kilogram of solvent, moles of solute/kg of solvent |
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| freezing point depression |
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| the freezing point of a solution is always lower than the freezing point of a pure solvent |
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| molal concentration (freezing) |
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| the difference between the freezing points of the solution and pure solvent is directly proportional, ΔTf=m*Kf |
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| boiling point elevation |
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| the boiling point of a solution is always higher than the boiling point of a pure solvent |
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| molal concentration (boiling) |
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| the difference between the boiling point of the solution and pure solvent is directly proportional, ΔTb=m*Kb |
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| osmosis |
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| the process in which solvent molecules pass through a semipermeable membrane that does not allow solute particles to pass |
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| osmotic pressure |
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| pressure that is needed to prevent osmotic flow of solvent |
