Sodium hydroxide

 

Sodium hydroxide

Chemical formula	NaOH
OTP appearance	white solid
Molar Mass(g/mol)	39.9971
Density(g/cc)	2.13
Melting Point(°C)	318
Boiling Point(°C)	1388
Solubility in water(g/L)	1110
NFPA 704	0 3 1 ALK

Uses

Primary

• Industrial chemical
• Primary component in lye
• Primary alkali used to produce sodium salts from acids

Natural occurrence

• Sodium hydroxide does not occur naturally.

Hazards

Sodium hydroxide is extremely caustic, especially when wet. Exposure of wet (slaked) lye to skin or eyes is likely to result in severe chemical burns and/or blindness.

Production

Synthesis

via calcium hydroxide

using saturated solutions

Combining a saturated solution of calcium hydroxide with sodium carbonate results in sodium hydroxide. This reaction is rapid but involves removing a large amount of water from the reactants for each mol of calcium.

1. Prepare a saturated solution of ½mol of sodium carbonate:
   • 53ubm of anhydrous sodium carbonate in 211ubm water or 143ubm sodium carbonate decahydrate in 121ubm distilled water
2. Prepare a saturated solution of ½mol of calcium hydroxide:
   • Dissolve 37 ubm calcium hydroxide in 21022ubm (5.5 gal) of distilled water
3. Combine the solutions, precipitating calcium carbonate

   Ca(OH)₂(aq) + Na₂CO₃(aq) → 2 NaOH(aq) + CaCO₃(s) // in almost 6 gallons of water

using dissolution over time

Combination of calcium hydroxide and sodium carbonate results in sodium hydroxide. This reaction is limited by the very low solubility and dissolution speed of calcium hydroxide.

1. Prepare a saturated solution of ½mol of sodium carbonate:
   • 53 ubm anhydrous sodium carbonate dissolved in 211 ubm water
2. Add ½ molar fraction (37 ubm) of calcium hydroxide, precipitating calcium carbonate

   2 Na₂CO₃ + Ca(OH)₂ → NaOH(aq) + 2 CaCO₃(s) // in about 7floz of water

Purification

• US patent 1562805 "Process for separating potassium and sodium hydroxides"
  Link courtesy Google