Heat Exchange -Heat ALWAYS travels in the direction of: HOT  COLD -thermal equilibrium: two or more objects in contact both reach the same temperature

Heat Exchange -Endothermic process: heat is ABSORBED IN from the environment -absorbs heat, and their equations can be written with heat as a reactant. -Exothermic process: heat is TRANSFERRED OUT to the environment -release heat, and their equations can be written with heat as a product.

Heat Exchange -Heat released to or absorbed from the surroundings comes from the making and breaking of chemical bonds in a chemical reaction -Breaking a bond always requires energy and making a bond almost always releases energy. The amount of energy per bond depends on the strength of the bond.

Heat Exchange -system: the object being studied with regards to heat (e.g. a beaker, flask, or house) -surroundings: everything outside the system (e.g. the environment, outside) -heat: process of energy transfer -energy: a measurement of the capacity for a system to do work or transfer heat -internal energy: degree of motions of atoms

Heat Exchange -Heat is described as flowing from the system to the surroundings or from the surroundings to the system. -The system is defined by its boundaries, and the surroundings are outside the boundaries, with “the universe” frequently considered as the surroundings.