Chapter 5 Terms Flashcards
thermochemistry
the study of the energy changes involve in chemical and physical processes
kinetic energy
energy of motion
potential energy
stored energy
joule
(J) The SI unit for energy; we often use kilojoules (kJ)
1 kJ = 1000 J
What are the 3 systems
open system, closed system, isolated system
open system
system can exchange energy and matter with the surroundings
closed system
can exchange energy BUT NOT matter with the surroundings
isolated system
cannot exchange energy or matter with the surroundings
thermal energy
the sum of all the kinetic energies of all the particles of a sample of matter (cannot be measured)
temperature
the measure of the AVERAGE kinetic energy of all the particles of a sample of matter
specific heat capacity, C
the amount of energy needed to increase 1 gram of a substance by 1.0°C
What is the specific heat capacity of aluminum
0.897 J/g°C
What is the specific heat capacity of water
4.184 J/g°C
What is the specific heat capacity of wood
1.26 J/g°C
first law of thermodynamics
law of conservation of energy
~ energy cannot be created or destroyed BUT can be converted from one form to another
~ can be represented as ΔE system = -ΔE surroundings
enthalpy
the total energy of a system plus the pressure times the volume
~ cannot measure BUT we can measure the enthalpy change ΔH
exothermic
heat is released from the system
~ feels hot; ΔH = negative
endothermic
heat is absorbed from the surroundings
~ feels cold; ΔH = positive
second law of thermodynamics
when two objects are in thermal contact, energy/heat will be transferred from the object at higher temperature to the object at lower temperature until both objects reach the same temperature
molar enthalpy
the amount of energy absorbed or released per mole of whichever substance is defined (kJ/mol)
ΔH°f (standard molar enthalpies of formation)
the change in enthalpy when 1 mol of a compound is formed directly from its elements in their most stable state at standard ambient temperature and pressure (SATP - 25°C and 100kPa) and ALL solutions have a 1.00M concentration
Whats the ΔH°f for atoms in their elemental state (ex. magnesium)
0 kJ/mol as they are already in the state and no energy is lost/gained
