8.1 - Energy Changes

• what is thermochemistry?

  study of energy (heat) changes in chemistry

  shows if a reaction is likely to happen & stability of compounds
• what's a system?

  just the material or mixture of chemicals being studied

  everything else is the surroundings
• what's a closed system like?

  cannot exchange matter with the surroundings but can exchange energy
• what's an open system like?

  can exchange energy and matter with the surroundings
• what's enthalpy change?

  the heat energy change in a reaction measured at constant pressure

  units: kJ mol -1
• standard conditions

  100 kPa

  a specified temperature, usually 298K