Chemistry Test Questions – Flashcards
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Unlock answers| The volume of gas is affected by a change in what two things? |
| pressure and temperature |
| Gases have relatively low ________ and low ______. |
| density/viscosity |
| G |
Gases are miscible. What does this mean? |
| That they mxi easily with other gases. |
What are the four units of pressure? And how are they all related? |
atmospheres; torr; mmHg; Pascals
1 atm=760 torr=760 mmHg=1.01E5 Pa |
What is included in the ideal gas equation PV=nRT |
pressure (atm) volume (L) number of moles R (constant) .08206 atm-L/mol-K |
| What are the rules for R as a constant as far as when to use it and what are each of the values? |
R for pressure (atm/torr) .08206 atm-L/mol-K
R for energy (heat/energy) 8.314 |
| What is Boyle's law? |
V1P1=V2P2 ; volume and pressure are indirectly proportional |
| What is shown in Charle's Law? |
| volume is proportional to temperature |
| What does Avogadro's Law state? |
| that volume is proportional to the number of moles |
What does STP stand for? what what are the values? |
standard temperature and pressure ; T= 0 degrees celsius 273.15 K ; P= 1 atm ; standard molar volume: 22.4 L |
| What is the definition of standard molar volume? |
one mole of any gas will occupy 22.4 L at STP. ; (depends on number of moles... it may double or triple) |
| State the law of partial pressures: |
| for a mixture of non-reacting gases, the total pressure is the sum of the partial (of individual) pressures for each gas |
| what theory allows us to derive certain equations regarding the motion of indivudal gas particles? |
| kinetic-molecular theory, KMT |
| KMT looks at the _________ in energy of the gas molecules |
| changes |
| Increasing temperature casues an increase in ________? |
| energy |
| What causes the average velocity and the collisions to increase? |
| increasing temperature |
| In the kinetic energy equation, which R is used? |
| R= 8.314 J/mol-K |
| the process in which a gas escapes (of leaks) from its container through a small hole |
| effusion |
| what is the law of effusion for an ideal gas? |
| the rate of effusion of a gas is inversely proportional to the square root of its molar mass |
| The rate of effusion compares what? |
| what rates of effusion between two different gases, A and B |
| Can the rate of effusion equation be replaced to solve for time? |
| most definitely |
| What is the motion of one gas moving through another gas? |
| diffusion |
at a given temperature, the energy and the speed of a molecule is inversely proportion to what? ; (rate of effusion equation) |
| mass |
| What value for R is used in the root-mean-square equation? |
| R= 8.314 J/mol-K |
IDEAL GASES: -work best as ____ pressure and ____ temperatures -assumes no ________ ______ -assumes no ______ ______ |
low/high intermolecular interaction molecular volume |
REAL GASES: -molecules have _______ size and occupy ______ -molecules have _______ forces that become significant when they are in close proximity -at ______ pressures attractive forces lead to the appearance of fewer ______ -at very _____ pressure the finite volume of molecules causes repulsion and leads to the appearance of more ____ |
finite/space attractive high/moles high/moles |
in the real gas equation: ; pressure values are adjusted to account for...? ; what is the constant? ; |
attractive interactions of intermolecular forces ; a |
in the real gas equation: ; volume is adjusted to account for the...? ; what is the constant? |
finite volume, molecular shape and the increased frequency of collisions ; b |
| who proposed the real gas equation? |
| van der waals |
what two components make up a majority of the earth's atmosphere?
in what proportions (%volume and mole fraction) |
nitrogen N2 78.084% .78084
oxygen O2 20.948% .20948
|
| what does the pressure at a given altitude depend on? |
| thew eight of the gases above it |
at a lower altitude the pressure is greater.
why? |
| because there is more gas above |
| pressure decreases and what increases? |
| altitude. |
| temperature in the atmosphere results from gas molecules ______ the sun's high energy ______. |
| absorbing/radiation |
| the absorption causes molecules to ? |
| ionize |
| warming is caused by the _______ cycle. |
| ozone |
| ozone absorbs what kind of light? |
| ultraviolet light |
| in photodissociation, how much energy is required to break O2 bonds? |
| 495 kJ/mol |
| the concentration of O2 ________ as altitude increases. |
| decreases |
ozone: - ___ resonance forms - ____ stable than O2 -_____ bond length than O2 -Bent angle at ____degrees -what color? |
2 less longer 117 light blue gas |
| what is the primary benefit of ozone? |
| it protects us from dangerous UV radiation |
how many reactions are needed to form ozone? ; how many reactions are needed to destroy ozone? |
2 ; 1 |
| what destroys ozone? |
| CFCs |
| where do CFCs diffuse to? |
| the upper atmosphere |
| when CFCs undergo photodissociation, what is released? |
| chlorine atom |
| what has replaced CFCs? |
| HFCs |
| what is the lowest portion of earth's atmospher? |
| troposphere |
| energy coming into the earth is mostly? |
| solar |
| what percentage of energy is reflected by the atmosphere? |
| 30% |
| what type of energy is absorbed by the atmosphere? |
| UV |
| Most of the radiation hits earth's surface and is absorbed. what does this cause? |
| warming |
| earth's surface radiates ehat back into the atmosphere in the form of ________ heat. |
| infrared |
| what absorbs infrared heat? |
| H2O, CO2, CH4, O3 |
| what gases in thermal regulation lead to the greenhouse affect? |
carbon dioxide
water |
| what are the three states of matter? |
| solid, liquid, gas |
Solid state: -_________ force between the particles is far _____ than the ________ _____ of the particles. |
| attractive/greater/kinetic energy |
solid state:
-particles remain in _______ -solid has a ______ shape -no _______ -no _____ ___ _____
stronger IF's mean... |
-position -specific -compressibility -ability to flow ; higher melting point |
Liquid state: ; ________ _____ of the particles is ______ than those in a solid but still weaker than the ______ ____ |
kinetic energy stronger attractive force |
liquid state: ; ___ = ____ |
| IF = KE |
liquid state: ; -kinetic energy allows for particles to ____ ____, but remain in virtual _____ -very low ______ -moderate ____ __ ____ |
tumble randomly/contact compressibility ability to flow |
| liquids with strong IF will have what? |
| higher boiling points |
Gas State: the _____ ____ of the particles is stronger than _____ _____ ; -occupy the shape of the _____ ; -high _______ -high _____ __ ____ |
kinetic energy attractive forces ; container ; compressibility ability to flow |
solid ---> liquid
endo or exo? |
melting/fusion
endo |
liquid ----> gas
endo or exo? |
vaporization
endo |
solid ---> gas
endo or exo?lo |
sublimation
endo
** at low pressure |
gas ---> liquid
endo or exo?
|
condensation
exo |
liquid ---> solid
endo or exo? |
freezing
exo |
gas ----> solid
endo or exo? |
deposition
exo |
what are the delta H symbols?
liquid and solid...
liquid and gas...
solid and gas... |
fus
vap
sub |
definition:
the amount of heat needed to change the temperature of 1 gram of a substance by 1 Kelvin |
| specific heat capacity |
| specific heat capacity is _____ for every compound in every ______/ |
| unique/phase |
| what specific heat capacity is replaced by molar heat capacity, what are the units? |
| J/mol-K |
Phase change:
during a phase shift, the ______ remains constant and all heat energy changes result from either _______ or ____ the _____ between the molecules within the substance |
temperature forming/breaking bonds |
| in the phase change from a gas to liquid or liquid to solid: the energy is _______ as molecules _____ bonds. |
| released/form |
| during phase changes from solid to liquid or liquid to gas, the energy is ____ and molecules _____ bonds. |
| absorbed/break |
energy changes are calculated using:
|
delta H: fusion delta H: vaporization |
| what is the first law of thermodynamics? |
| energy cannot be destroyed or created, only transferred |
| the amount of heat lost by a system ____ the amount of heat gained by the surroundings |
| equal |
| what are the two most common types of calorimeters? |
bomb calorimeters
coffee cup calorimeters |
| the rate of vaporization is greater than the rate of condensation. which causes for what to happen? |
| molecules break free from the surface of water and enter the gas phase |
| what will increase as more and more gaseous water molecules leave the surface? |
| pressure of the water vapor in the container |
| does the pressure eventually reach a maximum? |
| yes. |
| what causes for there to be a maximum in pressure? |
| the fact that the rate of vaporzation is now equal to the rate of condensation |
| when the rate of vaporization is now equal to the rate of condensation, what does this actually mean? |
| the same amount of water molecules are leaving the surface as there are joining the surface |
| a system is in equilibrium when... |
| the same amount of water molecules are leaving the surface as there are joining the surface |
| what happens when liquid's vapor pressure reaches the external pressure (usually atmospheric pressure)? |
| it boils |
| the boiling point at atmospheric pressure, 1 atm? |
| normal boiling point |
| at higher altitudes, water will boil at a _____ temperature |
| lower |
| what causes for more molecules in a liquid to escape to the gas phase? |
| higher temperature |
| what two major factors affect vapor pressure? |
| temperature and intermolecular forces |
temperature: -raising the temperature increases the _____ ____ of the molecules, making it easier for them to escape from the ______, and harder for them to _______.
-in general, the higher the temperature, the higher the ______ _______ |
kinetic energy/surface/return
vapor pressure |
intermolecular forces: -these are the _____ ____ that keep particles ______. Weake intermolecular forces allow the particles to _______ more easily.
-in general, the weaker the intermolecular forces, the higher the ______ _____. |
attractive forces/together/vaporize
vapor pressure |
| what two factors affect the phase of a substance? |
| pressure and temperature |
| what is the point at which all three phases are in equilibrium? |
| triple point |
| what is the point called where the liquid/gas line ends? |
| critical point |
| at the critical point, the liquid and vapor pressure are ______. |
| equal |
| beyond the critical temperature, what exists? |
| supercritical fluid |
for normal compounds, an increase in pressure will result in the phase change of liquid to solid, like CO2.
Why is this? |
| because the solid is denser than the liquid |
| why is the line screwed up for H2O in the phase diagram? |
| because water is denser than ice |
| what is a solution? |
| a solute dissolved in a solvent |
the maximum amount that can be dissolved into a fixed amount of a specific solvent at a given temperature.
what is this? |
| solubility of a solute |
| what are the six intermolecular forces? |
1. ion-dipole (ion-polar) 2. dipole-dipole (two polar molecules) 3. hydrogen bonding (H-NOF) 4. ion-induced dipole (ion-nonpolar) 5. dipole-induced dipole (polar-nonpolar) 6. dispersion (London) (nonpolar-nonpolar) |
| intermolecular forces directly affect... |
| solubility |
common solution:
_____ solvents ______ or ______ solutes |
liquid liquid/solid |
| what does "like dissolves like" mean? |
| substances with similar types of intermolecular forces are more likely to dissolve in each other |
solubility:
-ions and polar molecules will readily dissolve into ______ solvents
-nonpolar molecules will readily dissolve into ______ solvents |
polar
nonpolar |
when a solution is formed, energy is either ______ or ______.
which is measures by a change in ______. |
released/absorbed
enthalpy |
enthalpy
solute particles separate solvent particles separate solute and solvent mix |
endo endo exo |
| what must be added together in order to find the enthalpy of the solution? |
| the enthalpy of the solute, solvent, and mix |
| what does it mean if the change in H is positive? |
| the process is endothermic and the solute won't dissolve well in the solvent unless change in entropy is very high |
| What does it mean if change in H is negative? |
| the substances will readily dissolve |
what is it called when solvent particles surround a solute particle?
what is this called in water? |
solvation
hydration |
| when a solution is forming, solute particles break apart from one another and become dispersed in the solvent. but what can happen on occasion? |
| the solute particles collide with undissolved solute and recrystalize |
| rate of dissolving at first is faster than the rate of... |
| recrystalizing |
| when the rate of dissolving and the rate of recrystalizing occur, they will eventually even out which is called the |
| equilibium |
| if a solution contains the maximum amoutn of dissolved solute particles at a given temperature, it is considered... |
| saturated |
what if it has less than the maximum amount of dissolved solute particles?
what if it has more? |
unsaturated
supersaturated |
temperature and solubility:
for solids, increasing temperature ______ solubility.
for gases dissolved in water, increasing temperature ______ solubility. |
increases
decreases |
pressure and solubility
-as pressure increases, the solubility of a gas _______
|
| increases |
| what is the amount of solute present within a given volume of the solution? |
| concentration |
| how is molarity expressed? |
M
moles of solute/Liters of solution |
| when diluting, what changes? |
| volume |
| what are 5 ways to express concentration: the proportion of a substance in a mixture? |
1. molarity (M) 2. molality (m) 3. parts by mass 4. parts by volume 5. mole fraction (x) |
| what are concentrations measured in if they are very small amounts? |
| ppm and ppb |
| solutes that are cpaable of dissociating are often called... |
| electrolytes |
| strong electrolyate dissociate ______ in water and are _____ conductors of electricity. |
| completely/good |
| weak electrolyate only dissociate _____ and are _____ conductors. |
| partially/poor |
| nonelectrolyates do not _______ in water and are ________. |
| dissociate/non-conductors |
| if a water soluble comound is ionic, then it is definitely a... |
| strong electrolyte |
not all electrolyates are ionic compounds...
true or false
|
| true |
| ionic compounds are only good conductors if the compound is ... |
| soluble |
| colligative properties are ________ properties. |
| physical |
| colligative properties depends on the _______ of solute particles dissolved in a given solvent. |
| number |
| the four types of colligative properties that can affect a solution are: |
1. vapor pressure lowering 2. osmotic pressure changes 3. boiling point elevation 4. freezing point depression |
lowering vapor pressure
-the vapor pressure of a solution is always ______ than that of the pure solvent
-what law proves this? |
lower
Raoult's Law |
boiling point increase
a solution has a _______ boiling point than the pure solvent |
| higher |
freezing point decrease
-a solution freezes at a ______ temperature than a pure solvent |
| lower |
Van"t Hoff Factor, i -refers to how the amount of ______ _____ can increase if the solute itself i able to ______ into its constituent ions. -______ that are capable of _______ in solution are often called ________
|
solute particles/dissociate
solutes/dissociating/electrolytes |
osmotic pressure
-known also as ______ pressure -it is produced by a solution with a ________ in the concentration of solute
-- Van't Hoff factor refers to how the mount of solute particles ______ by a ________ factor if the solute is an ionic compound and _______ into its _________ ions. |
hydrostatic
differential
increases/specific/dissociates/constituent |
