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Environmental Chemistry - Kolev
Kolev
40
Environmental Studies
Undergraduate 2
06/06/2013

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Cards

Term
What are the main sources of anthropogenic contaminants?
Definition
Agriculture, industry and households
Term
Natural Contaminant sources
Definition
Animals, Plants, Minerals
Term
By-products of imcomplete burning in boilers
Definition
Fly ash, bottom ash, boiler slag
Term
Five main conditions for formation of photochemical smog
Definition
Heavy traffic, sunlight, high temp, ozone, quiet weather
Term
Natural sources of aerosols
Definition
Deserts, oceans, forests, fires, volcanoes
Term
What is an interferent?
Definition
Chemical species which affects the outcome of a measurement.
Term
How do you eliminate interferences?
Definition
Separating analyte from sample matrix. Part of sample pretreatment step.
Term
Seven steps of quantitative analysis
Definition
Method selection, Sampling, Solution Preparation, sample pretreatment, analytical measurement, calculating result, statistical evaluation
Term
When is a sample representative of the bulk of a material?
Definition
If its composition is identical to the average composition of the bulk material
Term
Steps in sampling?
Definition
Collection of a gross sample
Reduction of gross sample to homogeneous laboratory sample
Term
Three methods for calculating the analytical result
Definition
Calibration curve method, internal standards method, standard addition method
Term
What is the calibration equation?
Definition
C = (Z-a)/b
Term
Describe the standard addition method.
Definition
Known amounts of analyte are added to the sample with unknown analyte conc. The analytical signal is measured before starting the additions, and after each addition.
Term
Equation for multipoint standard addition of varying volumes
Definition
C = a/b
Term
When should varying volume multipoint addition be used?
Definition
When there could be changes to the sample matrix
Term
Equation for determining concentrating using multipoint constant volume
Definition
C = -[v(flask)*C/V(x)]
Term
When is the internal standards method used?
Definition
Instrument response varies slightly in time; Sample loss can occur during pretreatment
Term
Equation for the internal standards method
Definition
C = [(1/F)*(C(internal)/Z(internal)] * Z(analyte)
Term
What are the three main types of experimental error?
Definition
Systematic, random, gross
Term
How do you correct instrumental errors?
Definition
Calibration
Term
What is a gross error, and how do we determine a gross error?
Definition
Large outlier. Identified using statistical evaluation.
Term
Can we identify and quantify the source of random error?
Definition
No, as the error introduced is usually very small.
Term
How do we characterize precision and accuracy?
Definition
Precision - variance, standard deviation, RSD
Accuracy - Absolute or relative error
Term
What are the two main types of columns used in chromatography?
Definition
Packed columns and open tubular columns
Term
Three types of GC detectors
Definition
Flame-ionisation (hydrocarbons), Thermal conductivity, Electron capture detector (halogens)
Term
Diagram of GC
Definition
Gas tank - Pressure regulator - Sample port - Oven - Detector
Term
What are the requirements of the partition coefficient such that there is separation and preconcentration of the analyte?
Definition
K >> 1 ; [Sample] >> [Extractant]
Term
What is column resolution?
Definition
Quantitative measure of its ability to separate 2 analytes.
R = 2[(tb - ta)/(Wa + Wb)]
Term
Define "titration error"
Definition
The difference between the titrant volume to equivalence, and the actual titrant volume used.

Error = V(equiv.) - V(end)
Term
Diagram of AAS
Definition
Light source - Premix Burner (Sample, fuel, air) - Monochromator - Detector
Term
What are releasing agents and protective agents?
Definition
Releasing agents react preferentially. Protective agents form stable, non-volatile compound with the analyte.
Term
Why is the analysis of phosphoric compounds important?
Definition
Orthophosphate supports eutrophication, which leads to anoxic conditions.
Term
What are the main sources of ammonium salts as water comtaminants?
Definition
Decomposition of proteins, Atmospheric nitrogen, agriculture, cleaning products
Term
What are the main sources of anions as water comtaminants?
Definition
Erosion, sedimentary release, agriculture, soaps, sewage treatment
Term
What are the main organic derivatives as water comtaminants?
Definition
Organic decay, algae, oils, pesticides, detergents
Term
List aerosol control devices in order of increasing particulate size.
Definition
Electrostatic precipitators, Fabric filter separator, Scrubber, Cyclone, Settling chamber
Term
What are the effects of water hardness?
Definition
Interfering with cleaning tasks, Formation of mineral deposits in pipes, Flocculation of colloidal particles in soil.
Term
What are the parameters of water hardness?
Definition
< 60 mg/L - soft
>270 mg/L - hard
Term
Formula for the student t-test
Definition
mean - true > ts/sqrt(n) : no difference
Term
Formula for f-test
Definition
F =variance 1/variance 2 : compared with critical f value
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