Wet chemistry
![](https://upload.wikimedia.org/wikipedia/commons/thumb/2/24/Graduated_Cylinders_and_Beaker_filled_with_Chemical_Compounds.jpg/267px-Graduated_Cylinders_and_Beaker_filled_with_Chemical_Compounds.jpg)
Wet chemistryis a form ofanalytical chemistrythat uses classical methods such as observation to analyze materials. The termwet chemistryis used as most analytical work is done in the liquid phase.[1]Wet chemistry is also known asbench chemistry,since many tests are performed at lab benches.[2]
Materials
[edit]Wet chemistry commonly useslaboratory glasswaresuch as beakers and graduated cylinders to prevent materials from being contaminated or interfered with by unintended sources.[3]Gasoline,Bunsen burners,and crucibles may also be used to evaporate and isolate substances in their dry forms.[4][5]Wet chemistry is not performed with any advanced instruments since most automatically scan substances.[6]Although, simple instruments such as scales are used to measure the weight of a substance before and after a change occurs.[7]Many high school and collegelaboratoriesteach students basic wet chemistry methods.[8]
History
[edit]Before the age oftheoreticalandcomputational chemistry,wet chemistry was the predominant form ofscientific discoveryin the chemical field. This is why it is sometimes referred to asclassic chemistryorclassical chemistry.Scientists would continuously develop techniques to improve the accuracy of wet chemistry. Later on, instruments were developed to conduct research impossible for wet chemistry. Over time, this became a separate branch of analytical chemistry calledinstrumental analysis.Because of the high volume of wet chemistry that must be done in today's society and newquality controlrequirements, many wet chemistry methods have beenautomatedand computerized for streamlined analysis. The manual performance of wet chemistry mostly occurs in schools.[citation needed]
Methods
[edit]Qualitative methods
[edit]Qualitative methods use changes in information that cannot be quantified to detect a change. This can include a change in color, smell, texture, etc.[9][10]
Chemical tests
[edit]Chemical testsuse reagents to indicate the presence of a specific chemical in an unknown solution. The reagents cause a unique reaction to occur based on the chemical it reacts with, allowing one to know what chemical is in the solution. An example isHeller's testwhere a test tube containing proteins has strong acids added to it. A cloudy ring forms where the substances meet, indicating the acids aredenaturingthe proteins. The cloud is a sign that proteins are present in a liquid. The method is used to detect proteins in a person's urine.[11]
Flame test
[edit]The flame test is a more well known version of the chemical test. It is only used on metallic ions. The metal powder is burned, causing an emission of colors based on what metal was burned. For example,calcium(Ca) will burn orange andcopper(Cu) will burn blue. Their color emissions are used to produce bright colors in fireworks.[citation needed]
Quantitative methods
[edit]Quantitative methods use information that can be measured and quantified to indicate a change. This can include changes in volume, concentration, weight, etc.
Gravimetric analysis
[edit]![](https://upload.wikimedia.org/wikipedia/commons/thumb/3/3f/Hot_FIltration.jpg/220px-Hot_FIltration.jpg)
Gravimetric analysismeasures the weight or concentration of a solid that has either formed from aprecipitateor dissolved in a liquid. The mass of the liquid is recorded before undergoing the reaction. For the precipitate, a reagent is added until the precipitate stops forming. The precipitate is then dried and weighed to determine the chemicals concentration in the liquid. For a dissolved substance, the liquid can be filtered until the solids are removed or boiled until all the liquid evaporates. The solids are left alone until completely dried and then weighed to determine its concentration. Evaporating all the liquid is the more common approach.[citation needed]
Volumetric analysis
[edit]Volumetric analysis ortitrationrelies on volume measurements to determine the quantity of a chemical. A reagent with a known volume and concentration is added to a solution with an unknown substance or concentration. The amount of reagent required for a change to occur is proportional to the amount of the unknown substances. This reveals the amount of the unknown substance present. If no visible change is present, an indicator is added to the solution. For example, apH indicatorchanges color based on the pH of the solution. The exact point where the color change occurs is called theendpoint.Since the color change can occur very suddenly, it is important to be extremely precise with all measurements.[citation needed]
Colorimetry
[edit]Colorimetry is a unique method since it has both qualitative and quantitative properties. Its qualitative analysis involves recording color changes to indicate a change has occurred. This can be a change in shading of the color or a change into a completely different color. The quantitative aspect involves sensory equipment that can measure the wavelength of colors. Changes in wavelengths can be precisely measured and indicate changes in the mixture or solution.[citation needed]
Uses
[edit]Wet chemistry techniques can be used forqualitativechemical measurements, such as changes in color (colorimetry), but often involves more quantitative chemical measurements, using methods such asgravimetryandtitrimetry.Some uses for wet chemistry include tests for:[citation needed]
- pH(acidity, alkalinity)
- concentration
- conductivity(specific conductance)
- cloud point(nonionic surfactants)
- hardness
- melting point
- solids or dissolved solids
- salinity
- specific gravity
- density
- turbidity
- viscosity
- moisture(Karl Fischer titration)
Wet chemistry is also used inenvironmental chemistrysettings to determine the current state of the environment. It is used to test:[citation needed]
- Biochemical Oxygen Demand (BOD)
- Chemical Oxygen Demand (COD)
- eutrophication
- coating identification
It can also involve theelemental analysisof samples, e.g.,watersources, for chemicals such as:[citation needed]
- Ammonia nitrogen
- Chloride
- Chromium
- Cyanide
- Dissolved oxygen
- Fluoride
- Nitrogen
- Nitrate
- Phenols
- Phosphate
- Phosphorus
- Silica
- Sulfates
- Sulfides
See also
[edit]Further reading
[edit]- Elizabeth K. Wilson."Phoenix Tastes Water Ice On Mars".C&EN.
- Beck, Charles M. II. (February 15, 1994)."Classical Analysis: A Look at the Past, Present, and Future".Anal. Chem.66(4): 224A–239A.doi:10.1021/ac00076a718.S2CID242506938.
References
[edit]- ^Trusova, Elena A.; Vokhmintcev, Kirill V.; Zagainov, Igor V. (2012)."Wet-chemistry processing of powdery raw material for high-tech ceramics".Nanoscale Research Letters.7(1): 11.Bibcode:2012NRL.....7...58T.doi:10.1186/1556-276X-7-58.PMC3275523.PMID22221657.
- ^Godfrey, Alexander G.; Michael, Samuel G.; Sittampalam, Gurusingham Sitta; Zahoránszky-Köhalmi, Gergely (2020)."A Perspective on Innovating the Chemistry Lab Bench".Frontiers in Robotics and AI.7:24.doi:10.3389/frobt.2020.00024.ISSN2296-9144.PMC7805875.PMID33501193.
- ^Dunnivant, F. M.; Elzerman, A. W. (1988)."Determination of polychlorinated biphenyls in sediments, using sonication extraction and capillary column gas chromatography-electron capture detection with internal standard calibration".Journal of the Association of Official Analytical Chemists.71(3): 551–556.doi:10.1093/jaoac/71.3.551.ISSN0004-5756.PMID3134332– viaPubChem.
- ^Federherr, E.; Cerli, C.; Kirkels, F. M. S. A.; et al. (2014-12-15)."A novel high-temperature combustion based system for stable isotope analysis of dissolved organic carbon in aqueous samples. I: development and validation".Rapid Communications in Mass Spectrometry.28(23): 2559–2573.Bibcode:2014RCMS...28.2559F.doi:10.1002/rcm.7052.ISSN1097-0231.PMID25366403.
- ^Jackson, P.; Baker, R. J.; McCulloch, D. G.; et al. (June 1996)."A study of Technegas employing X-ray photoelectron spectroscopy, scanning transmission electron microscopy and wet-chemical methods".Nuclear Medicine Communications.17(6): 504–513.doi:10.1097/00006231-199606000-00009.ISSN0143-3636.PMID8822749.S2CID26111444.
- ^Costantini, Marco; Colosi, Cristina; Święszkowski, Wojciech; Barbetta, Andrea (2018-11-09)."Co-axial wet-spinning in 3D bioprinting: state of the art and future perspective of microfluidic integration".Biofabrication.11(1): 012001.doi:10.1088/1758-5090/aae605.hdl:11573/1176233.ISSN1758-5090.PMID30284540.S2CID52915349.
- ^Vagnozzi, Roberto; Signoretti, Stefano; Tavazzi, Barbara; et al. (2005)."Hypothesis of the postconcussive vulnerable brain: experimental evidence of its metabolic occurrence".Neurosurgery.57(1): 164–171, discussion 164–171.doi:10.1227/01.neu.0000163413.90259.85.ISSN1524-4040.PMID15987552.S2CID45997408.
- ^Campbell, A. Malcolm; Zanta, Carolyn A.; Heyer, Laurie J.; et al. (2006)."DNA microarray wet lab simulation brings genomics into the high school curriculum".CBE: Life Sciences Education.5(4): 332–339.doi:10.1187/cbe.06-07-0172.ISSN1931-7913.PMC1681359.PMID17146040.
- ^Neelamegham, Sriram; Mahal, Lara K. (October 2016)."Multi-level regulation of cellular glycosylation: from genes to transcript to enzyme to structure".Current Opinion in Structural Biology.40:145–152.doi:10.1016/j.sbi.2016.09.013.ISSN1879-033X.PMC5161581.PMID27744149.
- ^Makarenko, M. A.; Malinkin, A. D.; Bessonov, V. V.; et al. (2018)."[Secondary lipid oxidation products. Human health risks evaluation (Article 1)]".Voprosy Pitaniia.87(6): 125–138.doi:10.24411/0042-8833-2018-10074.ISSN0042-8833.PMID30763498.
- ^Elizabeth A. Martin, ed. (25 February 2010).Concise Colour Medical Dictionary.Oxford University Press. p. 335.ISBN978-0-19-955715-8.