CHEMISTRY FINAL FLASH CARD – Flashcards
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| limiting reactants |
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| substance in a reaction that limits the amount of product made |
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| excess reactant |
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| substance that you have leftovers of |
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| percent yield |
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| actual yield/theoretical yield *100% |
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| Kinetic theory of Matter |
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| -all the particles in a substance are in constant motion -state of matter is determined by amount of motion and spacing between particles -temperature: the measure of the average kinetic energy in a substance |
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| Kelvin |
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| Celcius + 273 |
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| solid |
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| particles are tightly packed and vibrating slightly |
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| liquid |
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| particles are further apart than solids and slip/slide around |
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| gas |
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| particles are very far apart and zip around |
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| behavior of "ideal" gases |
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| low density, high compressibility, high expansion, diffusion vs. effusion |
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| diffusion vs. effusion |
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| diffusion is movement of particles from areas of high concentration to low concentration. effusion is diffusion of a gas out of its container. |
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| Graham's law of effusion: |
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| Rate of A/ Rate of B = square root molar mass B/square root molar mass A |
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| Gas pressure |
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| force per unit area; force is exerted by the collision of gas particles against the sides of its container |
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| mm Hg/torr/KPa/psi/atm |
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| 760/760/101.3/14.7/1 |
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| STP |
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| standard temperature and pressure. set of environmental conditions by which we can compare gases. 0C and 1atm (273 K and 101.3 kPa |
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| Dalton's Law of Partial pressures |
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| total pressure of a mixture of gases is equal to sum of partial pressures of each gas |
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| London Dispersion Forces |
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| force of attraction created by the collision of two molecules which induces a dipole. weakest force |
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| Dipole-Dipole Forces |
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| when 2 polar molecules are attracted to each other |
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| Hydrogen bonding |
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| same as dipole-dipole, but one of the atoms is Hydrogen |
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| fluidity |
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| ability to flow. applies to liquids and gases. |
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| viscosity |
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| resistance to flow (liquids) |
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| density (liquids) |
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| much higher than gases |
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| surface tension |
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| attraction of particles toward the center of a liquid |
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| surfactant |
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| substance that disrupts surface tension |
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| capillarity |
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| tendency for a liquid to stick to the sides of its container |
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| properties of liquids |
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| fluidity, viscosity, surface tension, surfactant, density, capillarity |
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| density (solids) |
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| much denser than liquids (except water) |
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| Crystalline solids |
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| particles are arranged in repeating geometric pattern |
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| cubic unit cell |
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| all sides equal, all angles 90 degrees |
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| tetragonal unit cell |
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| two sides equal, all angles are 90 degrees |
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| orthorhombic unit cell |
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| no sides equal, all angles are 90 degrees |
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| rhombohedral unit cell |
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| all sides same, all angles equal but no 90 degrees angles |
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| lattice |
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| multiple unit cells together |
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| amorphous solids |
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| particles are arranged randomly. also known as "supercooled liquids" because they exhibit flow |
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| freezing |
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| removal of energy from liquid causes particles to slow down and get closer. freezing pt water: 0 C |
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| melting |
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| increase in energy causes particles to move faster and spread apart. melting pt water: 0 C |
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| Molar Heat of Fusion |
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| amount of energy needed to convert 1 mol from solid to liquid or vice versa at its melting/freezing point |
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| vaporization |
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| transition from liquid to gas |
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| evaporation |
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| molecules on the surface of the liquid gain enough energy to break off from the rest of the liquid. can happen at room temperature. |
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| boiling |
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| vapor pressure of the liquid must exceed the atmospheric pressure. boiling pt water: 100 C |
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| Molar Heat of Vaporization |
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| the amount of energy needed to convert 1 mol of any liquid to a gas at its boiling temperature. applies to vaporization and condensation. |
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| condensation |
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| transition from a gas to a liquid. condensation point: water 100 C |
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| sublimation |
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| transition from solid to gas |
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| deposition |
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| gas to solid without going through liquid |
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| triple point |
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| temperature and pressure at which all three states of matter are in equilibrium |
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| critical point |
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| critical temperature and pressure of a substance |
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| critical temperature |
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| temperature beyond which no amount of pressure can force a gas back into a liquid |
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| critical pressure |
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| when a substance is at its critical temperature, this is the minimum amount of pressure needed to make it a liquid |
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| ideal vs real gases |
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| 1. ideal gases do not attract or repel particles 2. ideal gases have completely elastic collision 3. gas particles have no particles of their own 4. gas particles are in constant random motion (Brownian motion) 5. all gases have same average kinetic energy at same temperature |
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| how are pressure and volume related? |
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| P1V1=P2V2 |
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| how are volume and temperature related? |
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| V1/T1=V2/T2 *temperature must be in Kelvin |
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| how are pressure and temperature related? |
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| P1/T1=P2/T2 temperature MUST be in Kelvin |
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| What is the combined gas law equation? |
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| P1V1/T1=P2V2/T2 Temp MUST be in kelvin! |
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| absolute zero |
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| temperature at which all motion in an substance ceases. 0K. (-273.15 C) |
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| Avagadro's Law |
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| 2 equivalent volumes of different gases at the same temperature and pressure will contain the same number of particles |
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| molar volume |
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| amount of space that 1 mol of gas occupies at STP. 22.4 L/Mol |
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| Ideal Gas Law |
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| PV=nRT R=ideal gas constant (.0821) also, PM=DRT |
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| solutions |
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| -homogeneous mixtures comprised of 2 or more substances in one distinct phase. -made up of solute (substance dissolved) and solvent (substance doing the dissolving) |
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| alloy |
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| solution of 2 or more metals |
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| miscibility |
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| the ability of 2 liquids to mix |
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| molar heat of solution |
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| when some substances dissolve, they gain (endothermic) or lose (exothermic) heat |
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| factors that affect dissolution rate |
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| surface area, stirring/agitation, and temperature. |
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| Increase in surface area causes __________ in rate of dissolution because.... |
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| increase; particles have greater access |
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| Increase in stirring causes __________ in dissolution because... |
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| increase; you are increasing Kinetic energy and contact |
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| Increase in temperature causes __________ in dissolution because... |
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| it increases kinetic energy and contact. |
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| unsaturated |
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| has under the maximum of solute dissolved (adding more solute = it would dissolve) |
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| saturated |
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| has the maximum of solute dissolved (adding more solute = it wouldn't dissolve) |
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| supersaturated |
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| has more than the maximum amount of solute dissolved. made by heating it up to increase solubility, then slowly cooling back down to suspend particles. (adding more solute pulls out all extra solute) |
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| an increase in pressure causes an __________ in solubility for GASES ONLY! |
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| REMEMBER for gases only!!! |
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| an increase in pressure causes an __________ in solubility for GASES ONLY! |
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increase
REMEMBER for gases only!!! |
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| effervescence |
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| rapid escape of a gas from a liquid |
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| how are saturation and pressure related? (Gases only) |
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| S1/P1=S2/P2 where S is measured in g/L at a constant temperature |
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| % by mass |
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| Mass of solute/Mass of solution |
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| percent by volume |
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| volume of solute/volume of solution |
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| Molarity (M) |
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| ratio of the number of moles of solute per liter of solution. unit is the molar. M=moles solute/volume solution |
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| Molality (m) |
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| ratio of number of moles of solute to mass in Kg of solvent. moles solute/mass (kg) solvent |
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| dilutions |
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| initial molarity * initial volume= final molarity * final volume |
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| mole fraction |
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| ratio of moles of solute to moles of solution #moles solute/#moles solute + #moles solvent |
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| colligative properties |
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| osmotic pressure, vapor pressure depression, boiling point elevation, freezing point depression |
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| osmotic pressure |
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| force of the water movement when it diffuses across a semi permeable membrane |
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| boiling point elevation |
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| when solute is added to solvent, the boiling point of the solvent increases. ?TB= i*m*Kb ions*molality*molal boiling point constant |
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| freezing point depression |
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| when solute is added to solvent, freezing point of solvent decreases. ?Tf=i*m*Kf ions*molality*constant |
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| vapor pressure depression |
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| force of a liquid trying to become a gas |
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| solutions |
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| particle sizes <1nm. homogeneous. do not settle upon standing. cannot be filtered. transmit light. |
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| colloids |
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| particle sizes: 1 nm-1000 nm. homogeneous/heterogeneous. can settle. can be filtered. Tyndall effect: scatter light. |
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| suspensions |
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| particles > 1000 nm. heterogeneous. settle upon standing. filterable. opaque; absorb light. |
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| law of conservation of energy |
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| energy can neither be created nor destroyed. measured in Joules. |
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| Specific Heat Capacity |
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| amount of energy needed to raise 1 g of a substance by 1 degree Celsius. unit: J/g*degrees Celsius. Cp=q/m*?T q is amount of heat energy, m is mass, ?t is change in temp |
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| In a thermochemical exothermic equation, energy is on _________ side of reaction. In a thermochemical endothermic equation, energy is on __________ side. |
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| product; reactant |
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| Enthalpy |
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| ?H. amount of energy transferred in a reaction. (+?H)=endothermic. (-?H)=exothermic. |
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| Hess' Law |
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| states you can add up the partial reactions to get the enthalpy of the full reaction |
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| ?Hreaction |
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| sum of ?Hf products- sum of ?Hf reactants pure elements have ?Hf values of 0 KJ. |
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| Entropy |
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| ?S. measure of the amount of disorder in a system. if disorder is increased, +?S. (ususally spon.) if disorder is decreased, -?S. (usually non spon). |
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| predicting POSITIVE ?S |
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| 1. converting substance from solid to liquid to gas. 2. dissolving a solid/liquid into solution. 3. increasing temperature. 4. if products have more gas particles than reactants in reaction. |
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| predicting NEGATIVE (?S) |
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| when a gas dissolves into solution |
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| ?G |
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| ?G=?H - T*?S. if reaction has -?G, then spontaneous. if reaction has +?G, then non spontaneous. |
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| reaction rate |
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| change in concentration/time |
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| collision theory |
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| 1. reactants must collide in proper orientation. 2. reactants must collide with enough force to form an activated complex. 3. activated complex sometimes needs an activation energy to make reactants react. |
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| activated complex |
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| temporary, unstable arrangement of atoms that break apart to form the products. |
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| factors that affect reaction rate |
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| temperature, surface area, catalysts, concentration, nature of the reactants. |
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| reaction rate laws |
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| mathematic relationship between the concentration of reactants and rate of reaction. k[A] |
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| complex reactions |
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| have two or more elementary steps |
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| intermediates |
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| substances that are formed over the course of the reaction that are then consumed in later elementary steps |
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| rate-determining step |
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| elementary step that occurs the slowest determines its overall rate |
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| Redox reactions |
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| aka oxidation-reduction reactions. Loss of electrons is oxidation, gain of electrons is reduction. |
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| oxidizing agent |
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| substance that oxidizes another substance but is itself reduced |
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| reducing agent |
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| substance that reduces another substance but is itself oxidized |
