Important Info Flashcards
(50 cards)
What is analytical chemistry?
The science of obtaining, processing, and communicating information about the composition and structure of matter.
What is qualitative analysis?
The identification of elements, species, or compounds in a sample.
What is quantitative analysis?
The determination of absolute or relative amounts of analyte present in a sample.
Define ‘element’.
Chemically the simplest substance that cannot be broken down using chemical processes.
What is an atom?
The smallest part of an element that can exist, consisting of a dense nucleus of protons and neutrons surrounded by moving electrons.
What is a molecule?
An electrically neutral group of 2 or more atoms.
Define ‘compound’.
A substance composed of 2 or more different atoms that have reacted chemically with each other.
What is an analyte?
Substance or compound of interest measured in an analytical procedure.
What is a matrix in analytical chemistry?
The components within a mixture that provide support and structure but are not directly relevant to the analytes of interest.
What is accuracy in analytical methods?
The degree to which the measured value represents the true value.
What is precision in analytical methods?
The degree to which repeated measurements under unchanged conditions show the same results.
How is mean calculated?
The sum of all data points divided by the number of data points.
What is standard deviation?
A measure of the spread or variation that exists from the mean value.
What does %RSD stand for?
Percent Relative Standard Deviation.
How is %RSD calculated?
%RSD = (σ / X̄) × 100.
What does %A represent?
Percent Accuracy.
How is %A calculated?
%A = 100 - [100 × (True Value - X̄) / True Value].
What does titrimetry measure?
Volume of standard reagent reacting with analyte.
What does gravimetry measure?
Weight of pure analyte.
What is chromatography used for?
Differential adsorption of separate analytes.
What does mass spectrometry measure?
Mass of analyte fragments.
What does spectroscopy measure?
Wavelength and intensity of light absorbed or emitted by analyte.
What does thermal analysis assess?
Physical changes of analyte when heated or cooled.
What factors influence the choice of analytical method?
- Purpose of analysis
- Time scale
- Cost
- Concentration of analyte expected
- Nature of sample
- Accuracy required
- Availability of reference material
- Possible interferences
- Degree of selectivity available.
