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
Are convenient for drying and storing liquids
Weighing bottles
Balances that are less precise than analytical balances are called
Auxiliary balances
Is a process in which a solid is cycled through heating, cooling, and weighing steps until its mass becomes constant to within 02. to 0.3 mg
Ignition to constant mass
A device for drying substances or objects
Desiccator
The most common way of removing moisture from liquids. This is to minimize the uptake of moisture
Oven drying
Examples of desiccant or chemical drying agent
Calcium sulfate, anhyd. calcium chloride, anhyd. magnesium perchlorate, etc
Heating at ___ to ____ for __ hour is sufficient to remove the moisture from the surface of most solids
105 to 110 C, 1 hour
Is a simple method for determining a series of sample masses
Weighing by difference
These substances rapidly absorb moisture from the atmosphere
Hygroscopic substances
Crucibles that are manufactured in fine, medium, and coarse porosities with maximum temp limit at 200 C.
Sintered-glass crucibles
This crucible serves only as containers
Simple crucibles
This crucible serve not only as containers but also filters
Filtering crucibles
Crucibles that have a perforated bottom that supports a fibrous mat that can tolerate temp of more than 500 C
Gooch crucibles
Give two filtering medium of gooch crucibles
Asbestos (old), Glass mats (new)
This filtering media for gravimetric analysis is slow, inconvenient, not inert, and cheap
Paper/ filter paper
This filtering media for gravimetric analysis is rapid, convenient, inert, and has a maximum ignition of >500 C
Gooch crucible
This filtering media for gravimetric analysis is rapid, convenient, inert, expensive, and has a maximum ignition of 200-500 C
Glass crucible
This filtering media for gravimetric analysis is rapid, convenient, inert, expensive, and has a maximum ignition of 1000 C
Porcelain crucible
This filtering media for gravimetric analysis is rapid, convenient, inert, expensive, and has a maximum ignition of 1450 C
Aluminum oxide crucible
A heavy-duty electric furnace that is capable of maintaining controlled temperatures of 1100 C and higher
Muffle furnace
the process of turning the crucible upside down in the adaptor and sucking water through inverted crucible
Backwashing
is the process of pouring a liquid gently so as not to disturb a solid in the bottom of the container
Decantation
A small section of the rubber tubing that dislodges the last traces of precipitate
Rubber policeman
The process in which a solid moves up the side of a wetted container or filter paper. This is a property of precipitates as it spreads over a wetted surface against the force of gravity
Creeping
This is used when a filtering crucibles can be used instead of paper
Vacuum filtration train
Unit of volume that is defined as one cubic decimeter (dm^3)
Liter
Unit of volume that is defined as one one-thousandth of a liter (10^-3 L)
milliliter
Volume may be measured reliably with a ___, ___, and _____
pipet, buret, and volumetric flask
Meaning of TC and TD
to contain, to deliver
The flask that is calibrated to deliver one specified volume
Volumetric flasks
This volumetric equipment permit the transfer of accurately known volumes from one container to another
Pipets
This pipet delivers a single fixed volume between 0.5 to 200 mL
Volumetric pipets
Pipets that are calibrated in convenient units to permit delivery of any volume up to a maximum capacity of 0.1 to 25 mL
Measuring pipets
Pipets that deliver adjustable microliter volumes of liquid
Handheld Eppendorf Micropipets
Is the curved surface of a liquid at its interface with the atmosphere
Meniscus
A volumetric instrument that has substantially greater precision than a pipet
Buret
Is the apparent displacement of a liquid level or of a pointer as an observer changes position. This happen when an object is viewed from a position that is not a right angle to the object
Parallax
A condition that causes the volume to appear smaller than its actual value if the meniscus is viewed from above. And the value became larger when the meniscus is viewed from below
Parallax
A measured fraction of the volume of a liquid sample
Aliquot
