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Cooling bath
Cooling bath
Cooling bath
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A typical experimental setup for an aldol reaction. Both flasks are submerged in a dry ice/acetone cooling bath (−78 °C) the temperature of which is being monitored by a thermocouple (the wire on the left).

A cooling bath or ice bath, in laboratory chemistry practice, is a liquid mixture which is used to maintain low temperatures, typically between 13 °C and −196 °C. These low temperatures are used to collect liquids after distillation, to remove solvents using a rotary evaporator, or to perform a chemical reaction below room temperature (see Kinetic control).

Cooling baths are generally one of two types: (a) a cold fluid (particularly liquid nitrogen, water, or even air) — but most commonly the term refers to (b) a mixture of 3 components: (1) a cooling agent (such as dry ice or ice); (2) a liquid "carrier" (such as liquid water, ethylene glycol, acetone, etc.), which transfers heat between the bath and the vessel; (3) an additive to depress the melting point of the solid/liquid system.

A familiar example of this is the use of an ice/rock-salt mixture to freeze ice cream. Adding salt lowers the freezing temperature of water, lowering the minimum temperature attainable with only ice.

Mixed solvent cooling baths (% by volume)[1]
% Glycol in EtOH Temp (°C) % H2O in MeOH Temp (°C)
0% −78 0% −97.6
10% −76 14% −128
20% −72 20% N/A
30% −66 30% −72
40% −60 40% −64
50% −52 50% −47
60% −41 60% −36
70% −32 70% −20
80% −28 80% −12.5
90% −21 90% −5.5
100% −17 100% 0

Mixed-solvent cooling baths

[edit]

Mixing solvents creates cooling baths with variable freezing points. Temperatures between approximately −78 °C and −17 °C can be maintained by placing coolant into a mixture of ethylene glycol and ethanol,[1] while mixtures of methanol and water span the −128 °C to 0 °C temperature range.[2][3] Dry ice sublimes at −78 °C, while liquid nitrogen is used for colder baths.

As water or ethylene glycol freeze out of the mixture, the concentration of ethanol/methanol increases. This leads to a new, lower freezing point. With dry ice, these baths will never freeze solid, as pure methanol and ethanol both freeze below −78 °C (−98 °C and −114 °C respectively).

Relative to traditional cooling baths, solvent mixtures are adaptable for a wide temperature range. In addition, the solvents necessary are cheaper and less toxic than those used in traditional baths.[1]

Traditional cooling baths

[edit]
Traditional cooling bath mixtures[4]
Cooling agent Organic solvent or salt Temp (°C)
Dry ice p-xylene +13
Dry ice Dioxane +12
Dry ice Cyclohexane +6
Dry ice Benzene +5
Dry ice Formamide +2
Ice Salts (see: left) 0 to −40
Liquid N2 Cycloheptane −12
Dry ice Benzyl alcohol −15
Dry ice Tetrachloroethylene −22
Dry ice Carbon tetrachloride −23
Dry ice 1,3-Dichlorobenzene −25
Dry ice o-Xylene −29
Dry ice m-Toluidine −32
Dry ice Acetonitrile −41
Dry ice Pyridine −42
Dry ice m-Xylene −47
Dry ice n-Octane −56
Dry ice Isopropyl ether −60
Dry ice Acetone −78
Liquid N2 Ethyl acetate −84
Liquid N2 n-Butanol −89
Liquid N2 Hexane −94
Liquid N2 Acetone −94
Liquid N2 Toluene −95
Liquid N2 Methanol −98
Liquid N2 Cyclohexene −104
Liquid N2 Ethanol −116
Liquid N2 n-Pentane −131
Liquid N2 Isopentane −160
Liquid N2 (none) −196

Water and ice baths

[edit]

A bath of ice and water will maintain a temperature 0 °C, since the melting point of water is 0 °C. However, adding a salt such as sodium chloride will lower the temperature through the property of freezing-point depression. Although the exact temperature can be hard to control, the weight ratio of salt to ice influences the temperature:

  • −10 °C can be achieved with a 1:2.5 mass ratio of calcium chloride hemihydrate to ice.
  • −20 °C can be achieved with a 1:3 mass ratio of sodium chloride to ice.[citation needed]

Dry ice baths at −78 °C

[edit]

Since dry ice will sublime at −78 °C, a mixture such as acetone/dry ice will maintain −78 °C. Also, the solution will not freeze because acetone requires a temperature of about −93 °C to begin freezing.

Safety recommendations

[edit]

The American Chemical Society notes[citation needed] that the ideal organic solvents to use in a cooling bath have the following characteristics:

  1. Nontoxic vapors.
  2. Low viscosity.
  3. Nonflammability.
  4. Low volatility.
  5. Suitable freezing point.

In some cases, a simple substitution can give nearly identical results while lowering risks. For example, using dry ice in 2-propanol rather than acetone yields a nearly identical temperature but avoids the volatility of acetone (see § Further reading below).

See also

[edit]

References

[edit]

Further reading

[edit]
[edit]
Revisions and contributorsEdit on WikipediaRead on Wikipedia

Cooling bath

View on Grokipedia
from Grokipedia
A cooling bath is a liquid mixture employed in laboratory chemistry to achieve and maintain low temperatures, typically ranging from 13 °C to −196 °C, for conducting reactions, extractions, or other processes that require precise thermal control. These baths are essential for slowing reaction rates, dissipating heat from exothermic processes, and enabling low-temperature chemistry, such as in organometallic synthesis or cryogenic studies. Common compositions include ice-salt mixtures (e.g., equal parts and NaCl) for −5 °C to −20 °C, acetone or with (solid CO₂) for −78 °C or −40 °C, and solvent-liquid nitrogen slush baths (e.g., or with liquid N₂) for −94 °C to −196 °C. More specialized mixtures, such as o- and with , allow reproducible temperatures from −30 °C to −70 °C with low and minimal agitation. Safety protocols emphasize continuous temperature monitoring, use of insulated Dewar flasks to prevent cracking, slow addition of to avoid excessive CO₂ bubbling or solvent freezing, and protective gear to mitigate risks like or asphyxiation from cryogenic agents.

Fundamentals

Definition and Purpose

A is a filled with a of solids and/or liquids that provides a stable low-temperature environment for cooling reaction vessels or samples in settings. These baths are essential tools in chemistry laboratories, particularly for maintaining controlled conditions during experiments where precise regulation below ambient levels is required. The primary purpose of a cooling bath is to influence chemical processes by reducing temperature, which helps control reaction rates, prevent runaway exothermic reactions, facilitate , or preserve temperature-sensitive materials. For instance, in , cooling baths slow down reaction kinetics to allow selective outcomes or intermediate isolation, while in analytical techniques, they maintain low temperatures for samples like those in NMR spectroscopy to enhance . Basic components of a cooling bath include a sturdy container, such as a Dewar flask for insulation or a standard beaker for simpler setups, along with cooling agents like or combined with solvents to achieve the desired chill. Stirring mechanisms, often magnetic stirrers, are commonly incorporated to promote even temperature distribution within the bath. Heat transfer in cooling baths relies on fundamental principles: conduction transfers thermal energy directly from the immersed vessel to the surrounding bath medium, while convection circulates the chilled fluid to prevent localized hot spots and ensure consistent cooling. This combination allows for efficient and uniform temperature control without direct contact between the cooling mixture and the sample.

Historical Development

The concept of cooling baths dates back to at least the , when described mixtures of snow and (potassium nitrate) to achieve very low temperatures. In 19th-century chemistry laboratories, simple -water mixtures were routinely used to achieve near-freezing temperatures for controlling reaction rates and preserving samples in organic and analytical experiments. These rudimentary setups, often consisting of crushed suspended in within a container, represented a practical means of low-temperature maintenance in scientific practice, evolving alongside the growth of synthetic chemistry. By the mid-19th century, the introduction of piped and gas in labs further facilitated such cooling techniques, enabling more consistent application in diverse experimental contexts. A major milestone came in 1925 with the commercialization of —solid —initially by Prest Air Devices (later the Dry Ice Corporation of America), which allowed cooling baths to reliably reach −78 °C when combined with solvents like acetone, transforming low-temperature by enabling reactions previously limited by available cooling methods. The mid-20th century witnessed significant expansion in the use of mixed-solvent baths, which offered tunable freezing points for precise temperature control between −78 °C and −17 °C, as systematically explored in compositions pairing with organic liquids such as or . These innovations, documented in laboratory technique literature from onward, became staples in for stabilizing reactive intermediates and facilitating selective reactions. Following , cooling baths began integrating with cryostats and emerging automated systems in the , providing enhanced stability for specialized applications like tissue sectioning and spectroscopic studies, though manual configurations persisted as the primary choice for routine benchtop use due to their simplicity and cost-effectiveness.

Types of Cooling Baths

Aqueous-Based Baths

Aqueous-based cooling baths utilize or solutions as the primary medium to achieve temperatures typically ranging from 0 °C to around -50 °C, leveraging the solvent's high and the principle of for controlled cooling in laboratory settings. These baths are particularly suited for reactions requiring mild near ambient conditions, such as in where precise temperature control prevents unwanted side reactions without the need for specialized equipment. The simplest and most common aqueous-based bath is the ice-water bath, which maintains a stable temperature of 0 °C. It is prepared by mixing crushed and in a 1:1 ratio by volume to form a , ensuring the remains in equilibrium with the phase for consistent cooling. This setup is widely used for initial cooling of reaction mixtures or condensers in distillations. To achieve sub-zero temperatures, salts are added to or mixtures, exploiting to lower the bath temperature. For example, a (NaCl) solution or ice-salt mixture can reach -5 °C to -21 °C, depending on the concentration and mixing; equal parts and NaCl typically yield -15 °C to -20 °C when finely crushed and stirred. More aggressive cooling employs (CaCl₂) solutions; a 20% CaCl₂ freezes at -20 °C, while higher concentrations up to about 30% can extend to -50 °C before the eutectic limit is approached. These variations allow for targeted temperatures between -20 °C and -50 °C by adjusting salt . The effectiveness of these salt additions stems from , described by the equation ΔTf=Kf⋅m⋅i\Delta T_f = K_f \cdot m \cdot i, where ΔTf\Delta T_f is the change in freezing point, KfK_f is the (1.86 °C/m for ), mm is the of the solute, and ii is the van't Hoff factor for dissociation (e.g., i=2i = 2 for NaCl, i=3i = 3 for CaCl₂). This colligative enables predictable without complex machinery. Aqueous-based baths offer key advantages, including low cost due to readily available materials like and common salts, non-flammability for safer handling compared to organic solvents, and straightforward preparation requiring only basic mixing. However, their utility is limited to temperatures above approximately -50 °C, as further depression leads to solidification of the mixture, reducing efficiency. For colder requirements, non-aqueous alternatives are necessary.

Solvent-Based Baths

Solvent-based cooling baths employ organic s or their mixtures to attain intermediate low temperatures, ranging from -10 °C to -100 °C, enabling precise thermal control in laboratory reactions that demand conditions. These baths leverage the freezing points of selected solvents, often forming mixtures by partial solidification, which provides stable and reproducible temperatures without the need for cryogens like . Common examples include pure solvent baths, where the solvent is cooled until it reaches equilibrium between and phases, offering low for efficient . Prominent pure solvent options include , which forms a bath at its freezing point of -63 °C when cooled appropriately, and , achieving -95 °C at its freezing point of -96.7 °C. Acetone similarly provides a bath at approximately -95 °C, corresponding to its freezing point of -94.7 °C, often prepared by adding to the solvent in a Dewar flask until formation occurs. These temperatures are tunable by solvent selection, with the bath maintained by occasional stirring to ensure uniformity. For milder cooling, mixed-solvent systems are used; a 30% methanol-water (by mass) freezes at -40 °C, while a 20% reaches -26 °C, allowing access to -10 °C to -20 °C ranges suitable for less extreme sub-ambient conditions. combined with salts, such as , can yield baths at -15 °C, providing a simple alternative for intermediate cooling. These baths excel in applications requiring dry environments, such as the preparation of Grignard reagents, where temperatures below 0 °C suppress unwanted side reactions like Wurtz coupling while maintaining reagent stability in solvents. The nature of organic solvents prevents , a key advantage over aqueous alternatives used for higher-temperature cooling. By choosing solvents with specific freezing points, chemists can customize bath temperatures to match reaction kinetics, enhancing selectivity and yield in organometallic syntheses.

Cryogenic Mixtures

Cryogenic mixtures employ solid or liquid cryogens combined with s to achieve temperatures significantly below those of conventional solvent-based baths, enabling applications requiring extreme cold. These baths typically involve (solid CO₂) or (LN₂) as the primary cooling agents, dispersed in organic solvents to form stable, low-temperature slurries. Unlike warmer solvent baths used for moderate cooling, cryogenic mixtures are essential for processes demanding rapid extraction at sub-zero temperatures. The primary example is the dry ice-acetone bath, which maintains a of approximately −78 °C. This mixture consists of solid CO₂ pellets or chunks added to acetone, where the solvent prevents the dry ice from clumping while the bath stabilizes at the sublimation point of CO₂. sublimes at −78.5 °C under standard (1 ), ensuring the bath remains at this equilibrium without freezing the acetone solid. Variations of these mixtures allow for adjustable low temperatures depending on the solvent and cryogen used. For instance, in methanol produces a bath at approximately -78 °C. combined with ethanol achieves around −115 °C, as the solvent forms a slurry that moderates the cryogen's extreme cold. alone, used in insulated Dewar flasks, provides the lowest temperature of −196 °C, corresponding to its at 1 atm. More specialized mixtures, such as o- and with , allow reproducible temperatures from −30 °C to −70 °C with low and minimal agitation. These baths offer advantages in specialized applications such as flash freezing biological samples to preserve structure or conducting low-temperature spectroscopy to study reaction intermediates. However, a key limitation is the rapid sublimation or evaporation of the cryogen, necessitating frequent replenishment to sustain the desired temperature. Bath maintenance involves balancing heat input from the environment or sample, governed by the equation for heat transfer: Q=m⋅c⋅ΔTQ = m \cdot c \cdot \Delta T where QQ is the heat absorbed, mm is the mass of the solvent, cc is its specific heat capacity, and ΔT\Delta T is the temperature change, highlighting the need for sufficient cryogen to counteract thermal loads.

Preparation and Operation

Setting Up Baths

Setting up a cooling bath begins with selecting an appropriate container to ensure insulation and stability. Polystyrene foam boxes or Dewar flasks are commonly used for their thermal insulation properties, which help maintain low temperatures efficiently during reactions. The container should be sized to accommodate the reaction vessel while allowing sufficient space for the cooling mixture for effective heat transfer. The general procedure involves adding the cooling agent gradually to the to achieve the desired temperature without sudden thermal shocks. For instance, in aqueous-based baths, is first added to the , followed by ice chunks to form a that facilitates uniform cooling around 0 °C. Once prepared, the reaction vessel—often a —is immersed into the bath gradually to prevent cracking from . Continuous stirring is essential during immersion and operation to promote even temperature distribution and prevent localized hot spots in the reaction mixture. Essential equipment includes low-temperature alcohol thermometers for initial verification of bath temperature and magnetic stirrers or bars to ensure agitation of the cooling mixture. For solvent-based or cryogenic baths, insulated gloves and are used to handle components safely during assembly. To achieve uniform cooling, the stirrer speed should be adjusted to create gentle circulation without splashing, and the reaction vessel positioned centrally in the bath. Common troubleshooting issues include the bath freezing solid, particularly in cryogenic mixtures, which can be avoided by adding or slowly to the to prevent rapid solidification. If uneven cooling occurs, additional stirring or repositioning of the vessel may be necessary. For scaling to batch size, the bath volume should be significantly larger than the reaction vessel volume to ensure adequate submersion and , with larger batches requiring proportionally bigger containers.

Temperature Control and Monitoring

Maintaining stable temperatures in cooling baths is essential for reproducible experimental outcomes, particularly in chemical reactions where precise control prevents unwanted side products or thermal runaway. Insulated containers, such as Dewar flasks, are commonly employed to minimize heat ingress from the ambient environment by reducing conductive and convective losses. Periodic addition of coolant, like gradual incorporation of dry ice into solvent mixtures, helps sustain low temperatures without sudden fluctuations that could compromise reaction conditions. In advanced laboratory setups, feedback loops integrated with thermostats enable automated regulation, where sensors detect deviations and adjust coolant flow or heating elements via proportional-integral-derivative (PID) controllers to achieve dynamic stability. Temperature monitoring relies on reliable tools to verify bath conditions in real time. Digital thermometers and thermocouples provide direct immersion measurements with high precision, often calibrated against standards like NIST-traceable references. sensors offer non-contact monitoring, useful for avoiding in sensitive setups, though they require line-of-sight access and calibration for reflective surfaces. Several factors influence temperature stability in cooling baths, including ambient , which can accelerate evaporative cooling or introduce moisture-related inconsistencies, and vessel insulation quality, where poor sealing leads to rapid heat gain. Heat loss or gain can be quantitatively modeled using the convective equation: q=hAΔTq = h A \Delta T where qq is the heat transfer rate, hh is the heat transfer coefficient, AA is the surface area, and ΔT\Delta T is the temperature difference between the bath and surroundings; this relation underscores the importance of minimizing AA and ΔT\Delta T through insulation. Best practices for temperature management include logging profiles at regular intervals using data acquisition systems connected to monitoring tools, which facilitates analysis of drift over time and enhances reproducibility across experiments. Such records, often stored digitally, allow researchers to correlate temperature variations with reaction kinetics and validate protocol consistency.

Safety and Best Practices

Common Hazards

Cooling baths present several physical hazards primarily due to extreme low temperatures and the physical properties of the materials involved. Cryogenic cooling baths, such as those using or , can cause severe or cold burns upon direct skin contact, as the rapid freezing of tissues leads to extensive damage even with brief exposure. Slippery surfaces from spilled water, ice, or condensed moisture around aqueous or ice-based baths increase the risk of slips and falls in laboratory settings. Additionally, rapid cooling can induce in glass or vessels, leading to breakage if the is not rated for such temperature differentials. Chemical hazards arise from the components used in solvent-based and salt-enhanced baths. Organic solvents like acetone, commonly employed for low-temperature baths, are highly flammable with a of -20 °C, posing a or risk if vapors ignite near heat sources or sparks. Salts such as (CaCl₂), used to lower the freezing point in aqueous mixtures, can cause , dryness, redness, or burns upon prolonged contact due to their hygroscopic and corrosive nature. Environmental risks are particularly notable with dry ice-based baths, where sublimation releases carbon dioxide (CO₂) gas, potentially leading to asphyxiation in confined or poorly ventilated spaces by displacing oxygen and causing symptoms like , , or . Explosions from sealed containers can occur due to pressure buildup in reactive mixtures, such as dry ice combined with water, where rapid CO₂ production can shatter vessels and cause shrapnel injuries.

Precautions and Disposal

When handling cooling baths, laboratory personnel must employ preventive measures to minimize risks associated with chemical and cryogenic exposures. Appropriate (PPE), including insulated gloves, safety goggles or face shields, lab coats, and closed-toe shoes, is essential to protect against cold burns, splashes, and chemical contact. Work must be conducted in well-ventilated areas, such as under fume hoods, to prevent accumulation of hazardous vapors or from sublimation. Prior to setup, compatibility checks are critical. Operational precautions focus on controlled procedures to prevent and injuries. Glassware immersed in cooling baths should be cooled gradually to avoid and cracking, achieved by slowly adding cryogens like or rather than rapid immersion. In emergencies involving from cryogenic contact, immediate requires removing the affected area from the cold source and rewarming gradually in lukewarm (37–40°C) without rubbing, followed by evaluation; labs should maintain access to such protocols as part of their safety training. Disposal of cooling bath materials must comply with environmental regulations to prevent contamination. Aqueous salt solutions, such as those from (CaCl₂) baths, can be neutralized by dilution to below 5% concentration and discharged into the if local plumbing codes permit, provided they are non-hazardous. Solvent-based wastes require segregation as hazardous (e.g., non-halogenated solvents like acetone under EPA code F003) and recycling or professional disposal per (RCRA) guidelines, with post-2020 EPA updates promoting alternatives to reduce volatile organic compound emissions. sublimes naturally into CO₂ gas, which is self-disposing but must be vented in open, well-ventilated spaces to avoid asphyxiation risks. Regulatory frameworks, such as OSHA's 29 CFR 1910.1450, mandate a Chemical Hygiene Plan (CHP) for laboratories using hazardous chemicals in cooling baths, specifying PPE selection, ventilation standards, and safe handling procedures to limit exposures. In the 2020s, EPA principles have emphasized sustainable coolants, such as bio-based or low-toxicity solvents, to minimize waste and environmental impact in lab operations.

References

  1. https://chem.libretexts.org/Ancillary_Materials/Demos_Techniques_and_Experiments/General_Lab_Techniques/Cooling_baths
  2. https://chemtl.york.ac.uk/techniques/reaction-techniques/cooling
  3. https://www.chem.rochester.edu/notvoodoo/pages/magic_formulas.php?page=heating_and_cooling
  4. https://www.epfl.ch/labs/lcso/wp-content/uploads/2018/06/Coolingbaths.pdf
  5. https://www.radleys.com/blog/how-to-perform-reactions-at-low-temperatures/
  6. https://chem.libretexts.org/Bookshelves/Organic_Chemistry/Organic_Chemistry_Lab_Techniques_%28Nichols%29/01%253A_General_Techniques/1.04%253A_Heating_and_Cooling_Methods/1.4J%253A_Cooling_Baths
  7. https://www.uwyo.edu/chemistry/instrumentation/NMR/NMR-Useful-Tips.html
  8. https://berry.chem.wisc.edu/wp-content/uploads/sites/2203/2024/08/7-Heating-and-Cooling-Chemical-Mixtures.pdf
  9. https://www.chemistryworld.com/opinion/della-portas-salt-bath/4012036.article
  10. https://dryiceinfo.com/history/
  11. https://www.govinfo.gov/content/pkg/GOVPUB-C13-0ddd394a9cd4d3d56652a31d6b8177f5/pdf/GOVPUB-C13-0ddd394a9cd4d3d56652a31d6b8177f5.pdf
  12. https://www.oxycalciumchloride.com/siteassets/documents/guides/calcium-chloride-handbook.pdf
  13. https://chem.libretexts.org/Bookshelves/Introductory_Chemistry/Introductory_Chemistry_(CK-12)/16%3A_Solutions/16.13%3A_Freezing_Point_Depression
  14. https://pubs.acs.org/doi/10.1021/je60028a037
  15. https://www.engineeringtoolbox.com/methanol-water-d_987.html
  16. https://www.uaa.alaska.edu/about/administrative-services/departments/environmental-health-and-safety/_documents/acs-safety-academic-chemistry-lab.pdf
  17. https://ehrs.upenn.edu/health-safety/lab-safety/chemical-hygiene-plan/standard-operating-procedures/sop-cryogens-and-dry
  18. https://pubs.aip.org/aip/rsi/article/37/6/802/302759/Dry-Ice-Methanol-Bath-for-Temperatures-down-to-70
  19. https://research.usu.edu/ehs/chemical/liquid-nitrogen
  20. https://engineering.purdue.edu/mudawar/files/articles-all/2024/2024-18.pdf
  21. https://www.chem.rochester.edu/notvoodoo/pages/magic_formulas/cooling_baths.php
  22. https://www.mbl.edu/research/resources-research-facilities/national-xenopus-resource/protocols/nxr-cryosperm-ivf-tubes
  23. https://openbooks.lib.msu.edu/orgchemlabmanual/chapter/heating-and-cooling13-2/
  24. https://www.moorparkcollege.edu/sites/moorparkcollege/files/media/pdf_document/2020/chem_12_expt3.pdf
  25. http://www.chem.rochester.edu/notvoodoo/pages/magic_formulas/cooling_baths.php
  26. https://home.sandiego.edu/~josephprovost/Chem102_Lab_Icecream.pdf
  27. https://www.omega.com/en-us/resources/thermostats-and-temperature-control-systems
  28. https://www.omega.com/en-us/resources/infrared-thermometer
  29. https://tark-solutions.com/applications/bath-cooling
  30. https://web.pdx.edu/~rueterj/courses/esr221/lab/7-heat-transfer-lab.html
  31. https://thecalculatedchemist.com/blogs/news/a-complete-guide-to-using-thermocouples-in-a-chemical-laboratory-to-monitor-reactions
  32. https://www.labmanager.com/controlling-an-experiment-s-temperature-29154
  33. https://ehs.lbl.gov/resource/esh-manual-pub-3000/ch29/
  34. https://support.al.umces.edu/safety/lab-safety/hazard-classes/laboratory-physical-hazards/high-low-temperatures/
  35. https://nj.gov/health/eoh/rtkweb/documents/fs/0006.pdf
  36. https://pubchem.ncbi.nlm.nih.gov/compound/Calcium-Chloride
  37. https://pubs.acs.org/doi/10.1021/acs.chas.3c00027
  38. https://ehs.umich.edu/wp-content/uploads/2022/06/Cryogenic-Liquids-Use.docx
  39. https://www.osha.gov/laws-regs/regulations/standardnumber/1910/1910.1450
  40. https://www.ncbi.nlm.nih.gov/sites/books/NBK55884/
  41. https://www.bsu.edu/-/media/www/departmentalcontent/facilities/pdf/bsu-sewer-disposal-nov-16-2011.pdf
  42. https://www.safety.rochester.edu/ih/dryicehandle.html
  43. https://www.epa.gov/greenchemistry/basics-green-chemistry
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