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.
quarrel (plural quarrels) 1  A diamond-shaped piece of coloured glass forming part of a stained glass window. 2  A square tile; quarry tile. 3  A square-headed arrow for a crossbow. 4  A small opening in window tracery, of which the cusps etc. make the form nearly square. 5  A four-sided cutting tool or chisel with a diamond-shaped end.