Potassium hydroxide or KOH is a strong base, as it dissociates wholly into its constituent ions in its aqueous solution. It is an inorganic compound and is typically known as caustic potash. It has many industrial applications based on its caustic nature and interaction with acid. Around 700k to 800k tonnes of KOH were synthesised in 2005.
Table of Content
- What is KOH?
- Properties of KOH
- Structure of KOH
- Reaction of KOH
- Synthesis of KOH
- Applications of KOH
- Frequently Asked Questions – FAQs
What is KOH?
Potassium hydroxide is an inorganic compound commonly known as caustic potash. It is a strong base exhibiting high thermal stability and low melting point. It is a hygroscopic compound, i.e. it absorbs atmospheric moisture and becomes sticky on exposure. On dissolution, with water, it turns into a clear solution. It exists as white to slightly yellow flakes or pellets in its solid form. It doesn’t possess any characteristic odour in its solid-state.
Properties of KOH
| Name of Compound | Potassium hydroxide |
|---|---|
| Molecular Formula | KOH |
| Synonyms | Caustic potash, Potash lye |
| Chemical Safety | Corrosive |
| Molecular Weight | 56.106 g/mol |
| Density | 2.044 g/cm3 |
| Boiling Point | 1,327 °C |
| Melting Point | 360 °C |
Structure of KOH
Synthesis of KOH
Hydrolysis of Potassium Salt
KCl on getting hydrolysed yields potassium hydroxide, hydrogen gas, and chlorine gas.
2KCl + 2H2O → 2KOH + Cl2 + H2
Reaction of Potassium Carbonate with Slaked Lime
Potassium Carbonate reacts with slaked lime, i.e. calcium hydroxide, to yield potassium hydroxide and calcium carbonate precipitate.
Ca(OH)2 + K2CO3 → 2KOH + CaCO3 ↓
Reaction of KOH
Reaction with Ester
KOH reacts with an ester to yield alcohol and potassium salt of carboxylic acid.
KOH + RCOOR’ → RCOOK + R’OH
When R’ is a long chain of an alkyl group, the resulting product is a potassium salt of long-chain fatty acid, i.e. a potassium soap.
Reaction with Inorganic compounds
KOH reacts with carbon dioxide to yield potassium bicarbonate.
KOH + CO2 → KHCO3
Similarly, potassium hydroxide reacts with silicon dioxide to yield potassium silicates.
2KOH + SiO2 → K₂O₃Si + H2O
Applications of KOH
- It is used as an electrolyte in an alkaline battery.
- It is used to synthesise deicers and biodiesel used in airport runways.
- It is to manufacture soft soaps and liquid soaps via saponification.
- It is used for preparing clinical specimens for visualising fungi in hairs, skin, and nails.
- It is used as a thickening agent and synthesises liquid fertilisers.
Frequently Asked Questions on KOH Strong or Weak
What is potassium hydroxide?
Potassium hydroxide is an inorganic compound commonly known as caustic potash. It is a strong base exhibiting high thermal stability and low melting point. It is a hygroscopic compound, i.e. it absorbs atmospheric moisture and becomes sticky on exposure.
Why is potassium hydroxide a strong base?
Potassium hydroxide or KOH is a strong base, as it dissociates wholly into its constituent ions in its aqueous solution.
How can you synthesise potassium hydroxide?
We can synthesise potassium hydroxide by hydrolysis of potassium salts.
For example, KCl on getting hydrolysed yields potassium hydroxide, hydrogen gas, and chlorine gas.
2KCl + 2H2O → 2KOH + Cl2 + H2
What are the applications of potassium hydroxide?
- Potassium hydroxide is used as an electrolyte in an alkaline battery.
- It is used to synthesise deicers and biodiesel used in airport runways.
- It is to manufacture soft soaps and liquid soaps via saponification.
- It is used for preparing clinical specimens for visualising fungi in hairs, skin, and nails.
- It is used as a thickening agent and synthesises liquid fertilisers.
Is potassium hydroxide a carcinogen?
No, potassium hydroxide is not a carcinogen but can cause skin irritation, swelling, or eye pain.
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