Chemistry 301 - Thermodynamics Formulas Questions with 100% Correct Solutions

internal energy - ΔU = Uf − Ui First Law of Thermodynamics - ΔU = q + w heat - substances not changing phase (per gram) - q = m⋅Cs⋅ΔT heat - substances not changing phase (per mol) - q = n⋅Cm⋅ΔT heat - substances that are changing phase (per gram) - q = m⋅ΔHtrans heat - substances that are changing phase (per mol) - q = n⋅ΔHtrans work - constant external pressure (Pext) - w = −PextΔV work - constant external pressure (Δngas) - w = −ΔngasRT work - (formula for Δngas) - Δngas = (#mol gas prod) - (#mol gas react) enthalpy to internal energy - H - H = U + PV enthalpy to internal energy - ΔH (constant pressure) - ΔH = ΔU + PΔV enthalpy to internal energy - ΔU (PΔV) - ΔU = ΔH − PΔV enthalpy to internal energy - ΔU (ΔnRT) - ΔU = ΔH − ΔnRT enthalpy to internal energy - conditional heat flow - constant pressure - ΔH = qP enthalpy to internal energy - conditional heat flow - constant volume - ΔU = qV calorimetry (qsys) - qcal = −qsys calorimetry (Ccal) - qcal = CcalΔT calorimetry - coffee-cup Calorimetry (constant pressure, qP) - qcal = mwater⋅Cs,water⋅ΔT [SDM note: not listed on the "Just the Formulas" list] calorimetry - bomb Calorimetry (constant volume, qV) - qcal = mwater⋅Cs,water⋅ΔT + ChardwareΔT Hess' Law - flip and scale - ΔHrxn = ΔH1 + ΔH2 + ΔH3 + ⋯ flip and scale various reactions to match the target reaction Hess' Law - heat of formation - ΔH∘rxn = ∑nΔH∘ f(products) − ∑nΔH∘f(reactants) look up heat of formation data from a table Hess' Law - bond energies - ΔH∘rxn = ∑nΔHbond(breaking) − ∑nΔHbond(making) entropy / Second Law of Thermodynamcs - ΔSuniv = ΔSsys + ΔSsurr entropy - (S) (Boltzmann formula) - S = k ln Ω Boltzmann Constant - k, with a value of 1.38 × 10−23 J/K which is the same as the universal gas constant, R, divided by Avogadro's number, NA [SDM note: This is not on the "Just the Formulas" list as such; k is part of the "entropy (S) - Boltzmann formula".] entropy - change via reversible heat flow - ΔS = qrev / T (constant T) entropy - change with changing T - ΔS = n Cm ln (Tf / Ti) (changing T, constant P)