Sodium hydroxide

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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
NFPA704.png
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

via 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:
  2. Prepare a saturated solution of ½mol of calcium hydroxide:
  3. Combine the solutions, precipitating calcium carbonate
    Ca(OH)2(aq) + Na2CO3(aq) 2 NaOH(aq) + CaCO3(s) // in almost 6 gallons of water
via dissolution

Any combination of calcium (hydr)oxide and sodium (bi)carbonate results in sodium hydroxide. This reaction is limited by the very low solubility and dissolution speed of calcium hydroxide.

  • Combine any sodium/calcium pair of these alternatives to produce 1 mol of sodium hydroxide (ubm = 1g)
    Na2CO3 + CaO + H2O 2 NaOH(aq) + CaCO3(s) // halve reactants (containing disodium compound) to get one mol of sodium hydroxide
    NaHCO3 + CaO NaOH(aq) + 2 CaCO3(s) + H2O
    2 Na2CO3 + Ca(OH)2 NaOH(aq) + 2 CaCO3(s)
    NaHCO3 + Ca(OH)2 NaOH(aq) + 2 CaCO3(s) + H2O

Purification

Testing

Storage

Disposal

See Also

References