GED PREP

• Converting ˚F to ˚C

  ˚C = (˚F - 32) x 5/9
• Converting ˚C to ˚F

  ˚F = ˚C x 9/5 + 32
• Converting ˚C to K

  K = (˚C + 273.15)
• Percent composition of an element

  n x molar mass of element / molar mass of compound x 100%
• Percent yield


  actual yield / theoretical yield x 100%
• Molarity (M)


  moles of solute / liters of solution
• Dilution of Solution


  MiVi = MfVf
• Boyle's law - Constant T and n

  PV = k
• Boyle's law - For calculating changes in pressure or volume


  P1V1 = P2V2
• Charles' law - Constant P and n

  V/T = k
• Charles' law - For calculating temperature or volume changes


  V1/T1 = V2/T2
• Avogadro's law - Constant P and T

  V = kn
• Ideal Gas equation


  PV = nRT
• Calculation of changes in pressure, temperature, or volume of gas when n is constant

  P1V1/T1 = P2V2/T2
• Calculation of density or molar mass of gas

  d = PM/RT
• Dalton's law of partial pressures

  Pi = XiPT
• Root-mean-square speed of gas molecules

  urms = (3RT/M)^0.5
• Van der waals equation

  (P + an^2/V^2) (V - nb) = nRT
• Heat capacity


  C = ms
• Calculation of heat change in terms of specific heat

  q = ms∆t
• Calculation of heat change in terms of heat capacity


  q = C∆t
• Electrical force


  Fel = kq1q2/r^2
• Potential energy


  V = kq1q2/r
• Calculation of standard enthalpy of reaction

  ∆H˚rxn = ∑n∆H˚f (products) - ∑m∆H˚f (reactants)
• First law of thermodynamics

  ∆E = q + w
• Work done in gas expansion or compression

  w = -P∆V
• Enthalpy


  H = E + PV
• Enthalpy (or energy) change for a constant-pressure process


  ∆H = ∆E + P∆V
• Enthalpy (or energy) change for a constant-pressure process


  ∆E = ∆H - RT∆n
• Relationship of wavelength and frequency


  u = λν
• Energy of a photon

  E = hν
• Energy of an electron in the nth state in a hydrogen atom

  En = -RH(1/n^2)
• Energy of a photon emitted as the electron undergoes a transition from the ni level to the nf level


  ∆E = hν = RH(1/ni^2 - 1/nf^2)
• DeBroglie Relationship


  λ = h/mv
• Uncertainty Principle


  ∆x∆p ≥ h/4π
• Formal charge on an atom in a Lewis structure

  total number of valence electrons in the free atom - total number of nonbonding electrons - 1/2(total number of bonding electrons)
• Enthalpy change of a reaction from bond energies


  ∆H˚ = ∑BE (reactants) - ∑BE (products)
• Dipole moment


  µ = Q x r
• Bragg equation


  2d sin θ = νλ
• Clasius-Clapeyron equation


  ln P = -∆Hvap/RT + C