Chemistry Unit 5: Energy and Enthalpy + Specific Heat and Calorimetry + Enthalpy of Formation

thermodynamics

the study of how energy converts

energy (E)

capacity to do work or produce heat; joules, kilojoules

law of conservation of energy

energy is neither created nor destroyed, it just changes forms

temperature (T)

measure of the motion of particles (avg kinetic energy)

heat (q)

transfer of energy between objects with a temperature difference

system

what you’re focused on

surrounding

everything else in the universe

exothermic

releases heat, q is negative, feels hot

endothermic

absorbs heat, q is positive, feels cold

internal energy

total energy = heat + work

enthalpy (H)

sum of internal energy (same as heat lost or gained by the system for us)

enthalpy equation

deltaH = H_products - H_reactants

calorimeter

device used to measure heat gained or lost in a reaction

specific heat capacity (C)

energy needed to heat 1g of a substance by 1ºC

calorimetry calculations

q = mCdeltaT or “m cat”

deltaT

final temperature - initial temperature

enthalpy of formation

change in enthalpy that forms 1 mole of a compound from its ELEMENTS

enthalpy of reaction

deltaHº_rxn = deltaHº_products - deltaHº_reactants