General
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|---|---|
| Name | Sodium hydroxide |
| Chemical formula | NaOH |
| Appearance | White solid |
Physical
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| Formula weight | 40.0 amu |
| Melting point | 596 K (323 °C) |
| Boiling point | 1663 K (1390 °C) |
| Density | 2.1 ×103 kg/m3 |
| Crystal structure | ? |
| Solubility | ? |
Thermochemistry
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| ΔfH0gas | -197.76 kJ/mol |
| ΔfH0liquid | -416.88 kJ/mol |
| ΔfH0solid | -425.93 kJ/mol |
| S0gas, 1 bar | 228.47 J/mol·K |
| S0liquid, 1 bar | 75.91 J/mol·K |
| S0solid | 64.46 J/mol·K |
Safety
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| Ingestion | May cause severe and permanent damage to the GI system. |
| Inhalation | Irritation for low exposures, may be harmful or fatal in higher doses. |
| Skin | Dangerous. Symptoms range from mild irritation to nasty ulcers. |
| Eyes | Dangerous. May cause burns, damage to cornea or conjuctiva. |
| More info | Hazardous Chemical Database |
| SI units were used where possible. Unless otherwise stated, standard conditions were used. | |
Sodium hydroxide (NaOH), also known as caustic soda or lye in North America, is a caustic metallic base used in industry (mostly as a strong chemical base) in the manufacture of paper, textiles, and detergents.
Sodium hydroxide is occasionally used in the home as an agent for unclogging stuck drains, but it is highly caustic and has a high danger of causing chemical burns, permanent injury or scarring, and blindness, due to its high reactivity. So, store it separately.
When sodium hydroxide reacts with water and fluids, it can become hot enough to cause fires. For this reason, it is important to have the proper type of chemical fire extinguisher on hand before working with sodium hydroxide. Store this product in an airtight container to prevent NaOH from absorbing water and CO2 from the air. It can create enough heat to ignite flammables (such as alcohols), so add slowly in biodiesel processor.
Sodium hydroxide is manufactured by electrolysis of an aqueous solution of sodium chloride. It is a by-product of the process that is used to make chlorine.
A solution of a small portion of lye diluted in water is used in the traditional method of making a pretzel. It is also a traditional ingredient in the making of soap, and for this purpose was historically obtained in an impure form by steeping wood ash in water for a long period.
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2 Lutefisk 3 French |
Biodiesel
For biodiesel, this is one of the main reactantss, like catalyst. Make sure you are purchasing anhydrous sodium hydroxide, because water turns biodiesel into soap (saponification).
However, it is more used than potassium hydroxide, KOH, because it dissolves in methanol much more easily than NaOH, and it doesn't "clump".
Another alternative in the future is to use sodium silicate instead of sodium hydroxide.
