The pH of Lithium Hydroxide in Water

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The pH of lithium hydroxide (LiOH) in water is between 10 and 11, making it a strong base. When LiOH is dissolved in water, it undergoes hydrolysis, forming hydroxide ions (OH-) and lithium ions (Li+). The hydroxide ions increase the pH of the solution, making it basic. The relationship between pH and conductivity in a lithium hydroxide solution has been studied in detail, and the conductivity of a LiOH solution depends on the concentration of LiOH and the concentration of hydrogen ions (H+) in the solution.

Understanding the Hydrolysis of Lithium Hydroxide

When LiOH is dissolved in water, it undergoes hydrolysis, forming hydroxide ions (OH-) and lithium ions (Li+). The reaction can be represented as follows:

LiOH → Li+ + OH-

The hydroxide ions increase the pH of the solution, making it basic. The pH of the solution can be predicted from the hydrolysis constant (Kh) of Li+, which is 2.5·10-14.

Relationship between pH and Conductivity in a Lithium Hydroxide Solution

PH of lithium hydroxide in waterImage source: OpenStax College

The conductivity of a LiOH solution depends on the concentration of LiOH and the concentration of hydrogen ions (H+) in the solution. The removal of H+ ions in pure water by OH- ions in the solute must be considered when calculating the conductivity of a LiOH solution.

When LiOH is added to de-ionized water, it is expected to cause an increase in pH above 7. However, the actual pH of the solution may vary depending on the presence of impurities and the conductivity of the water.

Applications of Lithium Hydroxide

Lithium hydroxide (LiOH) is used in various applications, including:

  1. Production of Cathode Materials for Lithium-ion Batteries: LiOH is preferred over lithium carbonate as a precursor for lithium nickel manganese cobalt oxides in the production of lithium-ion batteries.

  2. Lithium Grease Thickener: LiOH is used as a thickener in lithium-based greases.

  3. Carbon Dioxide Scrubbing: LiOH is used to remove carbon dioxide from air or other gas streams.

  4. Precursor for Other Lithium Compounds: LiOH is used as a precursor for the production of other lithium compounds.

  5. Nuclear Reactors: In nuclear reactors, LiOH (isotopically enriched in lithium-7) is used to alkalize the reactor coolant for corrosion control and as radiation protection against free neutrons.

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Conclusion

In summary, the pH of lithium hydroxide in water is between 10 and 11, making it a strong base. The conductivity of a LiOH solution depends on the concentration of LiOH and the concentration of hydrogen ions (H+) in the solution. LiOH is used in various applications, including the production of cathode materials for lithium-ion batteries, lithium grease thickener, carbon dioxide scrubbing, and as a precursor for other lithium compounds.

References

  1. Lithium Hydroxide (LiOH) – Properties, Structure and Uses – Turito. (2023, January 25). Retrieved from https://www.turito.com/blog/chemistry/lithium-hydroxide-lioh-properties
  2. What is the pH of lithium hydroxide in water? – ResearchGate. (2018, May 6). Retrieved from https://www.researchgate.net/post/What-is-the-pH-of-lithium-hydroxide-in-water
  3. The relationship between pH and Conductivity in a Lithium Hydroxide Solution. (2002, June 7). Retrieved from https://lss.fnal.gov/archive_notes/pbarnote/fermilab-pbar-note-674.pdf
  4. Lithium hydroxide – Wikipedia. (n.d.). Retrieved from https://en.wikipedia.org/wiki/Lithium_hydroxide
  5. XA9743692 IN SITU MEASUREMENT OF TEE EFFECT OF LIOH ON THE … (n.d.). Retrieved from https://inis.iaea.org/collection/NCLCollectionStore/_Public/28/034/28034569.pdf