Menu
Home
People
Places
Arts
History
Plants & Animals
Science
Life & Culture
Technology
Reference.org
Cooling bath
open-in-new
<p>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 <a href="/facts/Distillation/plDvUMxn">distillation</a>, to remove solvents using a <a href="/facts/Rotary_evaporator/451a3Tyy">rotary evaporator</a>, or to perform a <a href="/facts/Chemical_reaction/GpqWlKrz">chemical reaction</a> below room temperature (see <a href="/facts/Kinetic_control/HnnBoou1">Kinetic control</a>). </p><p>Cooling baths are generally one of two types: (a) a cold fluid (particularly <a href="/facts/Liquid_nitrogen/IGWI1h00">liquid nitrogen</a>, <a href="/facts/Water/0lkXnJPK">water</a>, or even <a href="/facts/Air/hQ95Jznz">air</a>) — but most commonly the term refers to (b) a mixture of 3 components: (1) a cooling agent (such as <a href="/facts/Dry_ice/BvW99HtH">dry ice</a> or <a href="/facts/Ice/BGvkKFjD">ice</a>); (2) a liquid "carrier" (such as liquid water, <a href="/facts/Ethylene_glycol/stFz6CVe">ethylene glycol</a>, <a href="/facts/Acetone/cVyJxKqw">acetone</a>, etc.), which transfers heat between the bath and the vessel; (3) an additive to depress the melting point of the solid/liquid system. </p><p>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. </p> Mixed solvent cooling baths (% by volume)<a class="footnote-ref" id="fnref:1" href="#fn:1"><sup>1</sup></a><table><tbody><tr><th>% Glycol in EtOH</th><th>Temp (°C)</th><th>% H2O in MeOH</th><th>Temp (°C)</th></tr><tr><td>0%</td><td>−78</td><td>0%</td><td>−97.6</td></tr><tr><td>10%</td><td>−76</td><td>14%</td><td>−128</td></tr><tr><td>20%</td><td>−72</td><td>20%</td><td>N/A</td></tr><tr><td>30%</td><td>−66</td><td>30%</td><td>−72</td></tr><tr><td>40%</td><td>−60</td><td>40%</td><td>−64</td></tr><tr><td>50%</td><td>−52</td><td>50%</td><td>−47</td></tr><tr><td>60%</td><td>−41</td><td>60%</td><td>−36</td></tr><tr><td>70%</td><td>−32</td><td>70%</td><td>−20</td></tr><tr><td>80%</td><td>−28</td><td>80%</td><td>−12.5</td></tr><tr><td>90%</td><td>−21</td><td>90%</td><td>−5.5</td></tr><tr><td>100%</td><td>−17</td><td>100%</td><td>0</td></tr></tbody></table>