Chem H: Thermochemistry Formulas

q = C x ∆t

Where C = heat capacity(J/ºC), and ∆t = the change in temperature (final - initial)

q = m x c x ∆t

Heat flow; Where m = mass, c = specific heat, and ∆t = change in temperature (final - initial)

Specific Heat of H₂O

4.18 J/gºC

q reaction = -q calorimeter

Represents how the heat flow for the reaction system is equal in magnitude but opp in sign to that of the calorimeter

q reaction = -C cal x ∆t

Bomb calorimeter; This can be used to find the amt of heat absorbed/evolved in a reaction if you know the heat capacity (C cal), and ∆t = change in temperature

∆H = ∆H₁ + ∆H₂

Hess's law in which ∆H must equal the sum of ∆H₁ + ∆H₂

q reaction at constant pressure = ∆H = H products - H reactants

Difference in enthalpy is equal to the heat flow for the reaction system

∆Hº = ∑∆Hºf products - ∑∆Hºf reactants

Standard enthalpy change; Finding the enthalpy of formation

∆E system = -∆E surroundings

Law of conservation of energy

∆E = q + w

First law of thermodynamics; Total change in energy equal to the sum of work and heat flow

∆H = qp

Heat flow at constant pressure is equal to change in enthalpy

∆H = qv

Heat flow at constant volume is equal to change in enthalpy

∆H = ∆E + ∆(PV)

Change in enthalpy is equal to the sum of change in energy and the change in the product of PV

∆H = ∆E + ∆ngRT

∆H vs. ∆E; Change in enthalpy is equal to the sum of change in energy and the product of the change in the number of moles of gas and RT where R = 8.31 J/mol K and and T is in kelvin