Ch 34: Preparing Samples for Analysis Flashcards
This changes the composition of the sample (e.g. the loss of volatile compounds, increase in water content, and reacting with the atmosphere)
Crushing or grinding
a device for grinding solids that are not too hard
Ball mill
A device that moves along three axes for vigorous grinding of samples
Mixer or mill
A device used for crushing hard, brittle materials
Plattner Diamond Mortar
Two forms of water in solid state
Essential and Non-essential Water
Is the water that is an integral part of the molecular or crystalline structure of a compound in its solid state
Essential Water
Example of essential water
solid hydrate/ hydrate salt
The water that is formed when a pure solid is decomposed by heat or other chemical treatment
Water of Constitution
The water that is physically retained by a solid as a consequence of physical forces
Nonessential water
Types of Nonessential water
Adsorbed water, Sorbed water, Occluded water
Type of nonessential water that resides on the surface of the particles of a material
Adsorbed water
The amount of water adsorbed on a solid _______ as the temperature of the solid ___________, eventually approaches 100 C.
decreases, increases
Surface chemistry of moisture usually occurs rapidly, with equilibrium being reached after 5 - 10 mins only
Adsorption
A type of nonessential water that is contained within the interstices of the molecular structure of a colloidal compound
Sorbed water
Surface chemistry of moisture usually takes time, reaching equilibrium for days or even weeks
Sorption
