Measuring instantaneous rates is the most direct way of determining the rate law of a reaction, but it is not always convenient, and it may not be possible to do so with precision.
piece (pÄs) n. 1. A thing considered as a unit or an element of a larger thing, quantity, or class; a portion: a piece of string. 2. A portion or part that has been separated from a whole: a piece of pie. 3. An object that is one member of a group or class: a piece of furniture.
table - a piece of furniture having a smooth flat top that is usually supported by one or more vertical legs; it was a sturdy table. altar, communion table, Lord's table - the table in Christian churches where communion is given. booth - a table (in a restaurant or bar) surrounded by two high-backed benches.