Thermodynamics Unit

Energy
1. Can be TRANSFERED
  1. HEAT
    1. Change in system's energy ΔE = q + W
      1. System
        ex) a solution of HCL and another of NaOH were mixed together in a beaker with a stir rod
        Solution Chem: only the HCl and NaOH melecules (H+, OH-)
      2. Surrounds
        EVERYTHING ELSE
      3. What Causes Chemical Rxns?
        Free Energy ("nature of reactants")
        ΔG = ΔH - TΔS
        ΔG: the max amount of energy that can be used to do work
        ΔH: energy transferred as heat
        TΔS: energy used to create disorder
        - : thermodynamically favoured (spontaneous)
        + : NOT thermodynamically favoured
        Calculate
        #1: Calculate ΔH from calorimtry OR Hess's OR ΔHf; then calculate ΔS using entropy values; and then plug in to find ΔG at a certain temp
        #2: Calculate ΔG using ΔGfº values
        (ΔG = ΣnΔGº (products)−ΣnΔGº (reactants))
        Entropy Δs: measure of disorder *more random wanted*
        2nd law: Entropy of Universe is always increasing
        ΔS = S(products) - S(reactants)
        ΔSrxn = ΣnSº(products) - ΣnSº(reactants)
        Positive value is WANTED
        Enthalpy
        1st Law of Thermodynamics: cannot be created or destroyed
        EXO
        ΔH = q = -
        ENDO
        ΔH = q = +
        can be calculated 4 ways
        #3 Hess's Law
        if a rxn is carried in 1 or several steps, the overall change in enthalpy is equal to the sum of the enthalpy changes for each step
        #2 Calorimeter
        Heat transfer cannot be directly measured
        Heat Capacity [kJ/K (or Cº)]
        Specific heat capacity: amount of heat needed to raise the temperature of 1 kg of a substance by 1 k [kJ/kg•K (or Cº)]
        ΔH rxn vs Δq rxn [ΔH = Δq/n]
        total amount of heat lost or gained by a rxn
        Using stoichiometry
        #1 Bond of Enthalpies
        Break bonds NEED energy
        For the image: A + B need energy to break up; C + D release energy when formed
        Form bonds REALEASE energy
        ΔH = ΣnBE - ΣnBE
        Σ = sum
        n = # of moles
        BE = bond energy *from exp't* values must be given
        #4 Enthalpy of Formation
        An arbitrary value that indicates how much heat would be lost/gained from experimental states
        ΔHº rxn=ΣnΔHºf (products)−ΣnΔHºf (Reactants)
        n: mol
        Most "Hº"'s will be given
      4. q (+): heat transferred IN
        q (-): heat transferred OUT
      5. w (+): work done ON the system
        w (-): work done BY the system
      6. ΔE is change in PE and KE of particles in a system
  2. WORK W = -PΔV
2. PE
3. KE
  1. Temperature
    1. Conversions
      1. C = K - 273
      2. C = (5/9)(Fº - 32)
    2. a measure of the average KE of particles in a system
      1. If KE doubles, the temp doubles as well
4. CANNOT BE CREATED OR DESTROYED

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Thermodynamics Unit

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	Criado por Rachel Todd quase 11 anos atrás