Ch 2 Chemicals, Apparatus, and Unit Operations of Analytical Chemistry Flashcards
These chemicals conform tot he minimum std set by the ACS and are used in analytical works
Reagent Grade
Chemicals that have been analyzed by the suppliers, and the result is printed on the container label. The NIST is an excellent source of these chemicals
Primary Standard Reagents
Chemicals of complex substances that have been exhaustively analyzed
Reference standards
The oxidation of the organic constituents of a sample with oxidizing reagents such as HNO3, H2SO4, etc, or a combination of reagents
Wet ashing
The sudden, often violent boiling that tends to spatter solution out of its container
Bumb
An instrument for determining mass with a maximum capacity that ranges from 1 g to a few Kg and precision at maximum capacity of at least 1 part in 10^5
Analytical balance
The most common type of analytical balance with a maximum load of 160 to 200 g and a precision of 0.1 mg.
Macrobalance
A type of analytical balance with a maximum load of 10 to 30 g and a precision of 0.01 mg.
Semimicroanalytical balance
A type of analytical balance with a maximum load of 1 to 3 g and a precision of 0.001 mg.
Microanalytical balance
A balance that appeared in the market in 1946 and rapidly replaces the equal-arm balance due to speed and convenience
Single-pan analytical balance
A traditional analytical balance that is tedious and time consuming
Equal-arm balance
A balance which have neither a beam nor a knife edge and superior to the single-pan analytical balance
Electronic analytical balance
A device in which a small electric signal causes a mechanical system to return to null position
Servo system
Where the pan is tethered to a system of constraints
Cell
The cell incorporates several ____ that permit limited movement of the pan and prevent torsional forces
Flexures
The mass of an empty sample container
Tare
The process of setting the balance to read zero
taring
Electronic balances generally feature an automatic _____ that causes the display to read zero
Taring control
Are prism-shaped agate or sapphire devices that from low friction bearings with two planar surfaces contained in stirrups
Knife edges
A mechanical device that raises the beams so that the central knife edge no longer touches its bearing surface
Beam arrest
This supports most of the mass of the pan and its content and thus prevents oscillation
Pan arrest
Mounted near the end of the beam opposite the pan. This device contains a piston that moves within the concentric cylinder
Air damper/ dashpot
This is a small transparent screen mounted on the beam, is scribed with a scale that reads 0 to 100 mg
Reticle
An inexpensive weighing paper for powdered or granular samples because particles have little tendency to adhere to this paper
Glassine paper
The process of making glassine paper is called
Calendering
Is the weighing error that develops when the object being weighed has a significantly different density from that of the std masses.
Buoyancy error