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18 Cards in this Set
- Front
- Back
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Heat Vs Temperature |
Heat = total energy. Temperature = average energy |
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Exothermic Reactions |
Occur when energy to make bonds > energy to break bonds. Heat is released to surroundings. (-∆H). Neutralization and combustion always exothermic. Products more stable than reactants. |
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Endothermic Reactions |
Occur when energy to break bonds > energy to make bonds. Heat is taken in by system. (+∆H) Reactants more stable than products. |
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Bond Enthalpy: |
Energy absorbed when bonds are broken and released when bonds are formed. XY --> X + Y +∆H X + Y --> XY –∆H ∆Hreaction = ∑∆Hbroken - ∑∆Hmade use lewis dot structure to see bonds made and broken |
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Enthalpy and ∆H |
Enthalpy is basically amount of heat. Q = mc∆T ∆H = q / moles ∆H for a reaction is: (sum of ∆Hf products) - (sum of ∆Hf reactants) |
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Enthalpy cycle |
Using ∆Hf, you can find the ∆H of a reaction using the heat of formation of the reactants and the products. ∆Hfreactants + ∆H = ∆Hfproducts |
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Compound <--> gaseous atom |
compound to gaseous atom = +∆H gaseous atom to compound = -∆H |
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Calculating wavelength to break bond: |
1. calculate energy per photon: (energy in joules) / (6.02 x 10^23) 2. Calculate wavelength: (6.63 x 10^-34)(3.00 x 10^8) / energy per photon 3. convert wavelength to nm wavelength x 1,000,000,000nm ––––––––––––––– 1 meter |
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Finding lattice formation |
Final product = ions ∆Hlattice = -∆Hºf(compound) + ∆Hºatom(element) + Bond enthalpy (if there is a coefficient to get rid of) + first ionization energy + electron affinity |
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Solution Enthalpy |
Change when one mole of solute is dissolved in a solvent to infinite dilution under STP. Solid to aqueous |
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Hydration Enthalpy |
One mole of its constituent gaseous ions is dissolved to form an infinitely dilute solution. Gas to aqueous Show strength between polar water molecules and separated ions. The smaller the radius of ion (cations), the more exothermic the hydration enthalpy due to greater attraction. |
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Lattice enthalpy |
change when change when 1 mol of crystals (i.e. an ionic lattice) breaks down to its component particles at an infinite distance apart: MaXb(s) --> aM b+(g) + bX a-(g) ∆H = + aM b+(g) + bX a-(g) --> MaXb(s) ∆H = - Solid to gas |
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Energy cycle: (lattice + solution + hydration) |
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Entropy |
Measure of the amount of disorder in a system (in J/K/mol). Entropy of gas > liquid > solid under same conditions |
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Factors that increase disorder |
-mixing particles (more combinations) -change of state to greater distance between particles -increased temperature -increased number of particles -number of particles in gaseous state increases (greatest increase in disorder) |
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Phase changes, ∆S and ∆H: |
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Calculating entropy changes: |
∆Sºreaction = ∑∆Sºproducts - ∑∆Sºreactants |
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Spontaneity (gibbs free energy) |
∆G = ∆H - T x ∆S reactions moving from less stable to more stable state. Depend on entropy and enthalpy of reaction. If a reaction is spontaneous, it will be more likely to occur. -∆H and +∆S = always spontaneous +∆H and -∆S = never spontaneous ∆G = 0 means state change, or transition between spontaneous and non-spontaneous |
