Chemistry week 1 Flashcards
first laboratory attached to a hospital
Munich, Germany: Hugo Wilhelm von Ziemssen (1895)
William Pepper Laboratory of Clinical Medicine at University of
Pennsylvania (Philadelphia).
US
looked back on experiments of Antoine-Laurent
de Lavoisier in pneumatic chemistry
Henry bence Jones
“few and scanty, indeed, are the
rays of light which chemistry has flung on the vital mysteries.”
Robert James Graves (1796–1853)
– first used the term “clinical
chemical laboratory” (“klinisch-chemischen Laboratorium”)
Johann Joseph Scherer (1814– 1869)
– complained that clinicians
do not use their chemistry laboratory services except when needed for
“luxurious embellishment for a clinical lecture,”
Max Josef von Pettenkofer (1818–1901)
defined as the measurement system used in many
countries such as the United States using pounds, yard, miles, pint, etc
English system
derived from the Greek word “metron” meaning
“measure”. This system of measurement is used in scientific work
which includes gram, meter, and liter.
Metric system
Reporting of laboratory results is often expressed in terms of
Substance concentration or mass of the substance
- It is the modern form of the metric system and is the world’s most
widely used system of measurement; used in both everyday commerce
and science. - Preferred in scientific literature and clinical laboratories
- Consists of seven independent base units, each unit represented by a
symbol
System international
Seven base of SI Units
Length -
Mass -
Time -
Quantity of substance -
Electric current -
Thermodynamic temperature -
Luminous intensity -
Length - Meter
Mass - Kilogram
Time - Second
Quantity of substance - Mole
Electric substance - Ampere
Thermodynamic temperature - kelvin
Luminous intensity - candela
Substance being dissolved
Solute
Substance in which the solute is dissolved
Solvent
Weight or volume of the solute present in a specified amount of the solvent or solution
Concentration of solution
Weight in volume percent solution (W/V)
Grams of solute (g) / volume of solution X 100
Volume in volume percent solutions (V/V)
Volume of solute (g) / Volume of solution X100
Weight in weight percent solution (W/W)
Grams of solute (g)/ Grams of solution X 100
Molarity
Number of moles of solute/ volume of solution in liters
OR
Mass of solute in grams/ MW of solute X volume of solution (L)
Molality
Moles of solute/ Mass of solvent in kilograms
OR
Mass of solute in grams/ MW of solute X mass of solvent (kg)
The combining capacity or power of an atom of an element compared to hydrogen whose combining capacity is taken as one
Valence
number of units that can replace 1 mole of HYDROGEN ions
Acid
number of units that can replace 1 mole of HYDROXYL ions
Base
Normality
molarity X valence
or
grams of solute/ volume solvent in liters X EW
Dilution
C1V1 = C2V2
Cab be heated up to 400-500c
Resistant to heat, corrosion, and thermal shock
Used when heating or sterilization is required
Borosilicate glass
Six times stronger than Borosilicate. Can be heated up to 800C
Corex
Acid and alkali resistant
Can be heated to 900C
Vycor
Most common resistant Borosilicate glassware in the laboratory
Beakers, Flasks, Pipettes
Made by removing all elements from borosilicate glass
Has good optical qualities, temperature capabilities, and is radiation-resistant
Not used for the type of glassware in the laboratory
High silica glass
Partially used for strong ALKALINE solution
Referred to as soft glass because it’s thermal resistance is much less than borosilicate glass
Used for digestion with strong ALKALI is made
For strong BASIC solution
High Alkali-Resistant glass
Amber container for solutions that can be deteriorated with light
Low actinic glass (actinic meaning relating to or denoting light able to cause photochemical reactions)
Used for the manufacture of weighing bottles
Develops less static surface changes
Poor resistance to high temp
Composed of mixture of the oxides of silicon, calcium, and sodium
Standard flint glass / Soda-lime glass
Used in light fitters, lamp bulbs, and lightning lenses
“Stained glass”
Colored and Opal glasses
Have thin metallic oxide permanently fine-bonded to the surface of the glass
Electronic application as heat shield to protect against infrared light
Coated glass
Mostly soda-lime, lead, and borosilicate of high optical purity
Used in making prisms, lenses, and optical mirrors
Optical glasses
Have higher thermal resistance, chemical stability, and corrosion resistance like borosilicate glasses
Useful in hot plates, tabletops, and heat exchanges
Glass ceramics
Made of soda-lime and lead
Useful in preventing transmission of huge energy radiation as gamma ray and x-rays
Radiation-absorbing glasses
Beginning to replace glassware in the laboratory setting
unique high resistance to corrosion and breakage as well as its varying flexibility, had made it most appealing
Inexpensive
Disposable to avoid carry-over contamination
Plastic wares
Unique group of resins with relatively inert properties
Unaffected by acids, alkalis, salt solutions, and aqueous solutions
Can be autoclaved
Polyolefins
Most common light source that has iodine or bromine vapor
Tungsten Iodine lamp
contains small amounts of halogen such as
iodine to prevent the decomposition of the vaporized tungsten from the very hot filament. Have fuse silica envelop which could provide high intensity of UV Light
Quartz Halide lamp
provides energy source with high output
in the UV range (down to 165 nm). Most commonly used for UV work.
Deuterium discharge lamp
used above 800 nm
Infrared Energy source
Wavelength of visible light
340-700 nm
Below 340 nm wavelength
Ultraviolet
Above 700nm wavelength
Infrared region
An electrically heated rod of rare earth element oxides
Merst glower
Uses silicon carbide
Globar
Exits narrow bands of energy at well-defined places in the spectrum (UV and Visible)
Mercury vapor lamp
Emits sharp line spectrum
Low pressure mercury lamp
Emits continuous spectrium
Medium and High-pressure Mercury lamp
Consists of a gas-tight chamber containing anode, a cylindrical cathode, and insert gas such as helium or argon. LIGHT SOURCE OF Atomic Absorption Spectophotometry
Hollow Cathode lamp
Minimizes unwanted or stray light and prevents the entrance of scattered light into the monochromator system
Entrance Slit
Isolate specific wavelength of light
Monochromator
Wide band pass filters (SB of 50nm).
Glass filters
Used to eliminate light below a given wavelength
Sharp Cut-Off types
Use dielectric material of controlled thickness between 2 thinly silvered pieces of glass
Narrow band pass
Lease expensive, pass a relatively wide band of radiant energy and have a low transmittance of the selected wavelength.
Not precise but inexpensive, simple, and useful
Colored glass filter
Colored glass filter band pass
35-50nm or more
Utilizes the wave character of light to enhance the intensity of the desired wavelength by constructive interference and eliminates other by destructive inference and reflections
Interference filter
Interference filter band pass
10-20nm
Wedge-shaped pieces of glass, quartz, NaCl, or some other material that allows transmission of lights
Disperse the white light into continuous spectrum of colors
can be rotated, allowing the only desired wavelength to pass through an exit slit
Prisms
Most commonly used monochromators
Produce linear spectrum or orders directed towards the exit slit and may need accessory filters for stray light
Prepared by depositing a thin layer of aluminum copper alloy
Diffraction gratings
Controls the width of light beam
Exit slit
Used to hold the solution in the instrument whose concentration is to be measured.
Cuvette/ Sample cell / Analytical cell
Cuvettes for solutions that do not etch glass
Borosilicate glass cuvette
Cuvettes that does not absorb UV radiation below 320nm
Quartz or plastic cuvette
Cuvettes that are good for 340 nm and above
Alumina Silica glass
Electron tube amplifying a current that can convert transmitted energy into an equivalent amount of electrical or photoelectric energy
Detectors (Photodetectors)
Most commonly used detector
Uses a series of electrodes to internally amplify the photo signal before leaving the tube
Photomultiplier tube
Simplest method of displaying output of the detection system
Meter
Used to check the wavelength accuracy
Didymium and holmium oxide filter
Verifies the absorbance accuracy on linearity
Neutral Density filters and Dichromate solution
Uses TWO photodetectors, for the sample beam and reference beam
Double beam in Space
Uses ONE photodetector and alternately passes the monochromatic light through the sample cuvette and then reference using a chopper
Double beam in time
The Principles are
* Measures concentration of element by detecting absorption of
electromagnetic radiation by atoms, rather than by molecules.
* The element is not excited but they are dissociated from their chemical
bonds and placed in the unionized, unexcited ground state.
* It is ideal for alkali metals that are not easily excited (e.g. calcium,
magnesium).
* Uses propane acetylene for flame emission
Atomic absorption spectrophotometry
Selects the desired wavelength from a spectrum of wavelength which could either be a prism or diffraction gratings
Monochromator
Uses photomultiplier tubes to measure the intensity of the light signal
Detector