Sodium acetate is an ionic compound consisting of sodium cations, Na(+), and acetate ions, C2H3O2(-). Like most acetates, it exhibits high solubility in water: 76g dissolves in 100ml at 0°C. The solubility, however, increases substantially at higher temperature. The precipitation of a solid from a solution results in decrease in the disorder of the system. That is, in the solution the ions move freely in random directions and therefore exhibit high disorder. When the ions combine to form solid crystallites, their freedom of motion becomes restricted. Scientists describe this as a decrease in the entropy, or disorder, of the system. The laws of thermodynamics stipulate that for a process exhibiting a decrease in entropy to occur spontaneously, such as the precipitation of a solid from a solution, the process must also liberate heat. Consequently, the introduction of a solid crystallite of sodium acetate will warm itself as the sodium acetate precipitates from solution.

The video supports the Europlanet Mars Collection of Educational Resources - 5. Brines on Mars, which delves into how saturated brine solutions affect the habitability of Mars.

https://www.europlanet-society.org/mars-collection-of-educational-resources-5-brines-on-mars/

Europlanet 2024 RI has received funding from the European Union’s Horizon 2020 research and innovation programme under grant agreement No 871149.