system - the defined body being studied
surrounding - everything outside the system
closed system - a particular quantity of matter being studied, there is no change in mass across the boundary (there can be a change in energy)
control volume - a region with a prescribed boundary being studied, there can be change in mass and energy across the boundary,
extensive property - value for overall system is the sum of values for the parts into which system divides (ex. mass, volume, energy)
intensive property - not additive, values are independent of size (ex. temperature, pressure, density)
equilibrium - there are no changes in in a systems observable properties
specific volume - volume per unit mass