Difference between revisions of "Calcium hydroxide"

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==Hazards==
 
==Hazards==
 
* Calcium hydroxide is alkaline. It can irritate the skin, eyes and lungs and should not be ingested in large quantities. Wash with fresh clean water after contact.
 
* Calcium hydroxide is alkaline. It can irritate the skin, eyes and lungs and should not be ingested in large quantities. Wash with fresh clean water after contact.
 +
==Character==
 +
* Calcium hydroxide,  calcium oxide, and calcium carbonate are  three interconvertable calcium compounds.
 +
** Calcium hydroxide can be converted to calcium oxide by heating to 580°C, where it loses one molar  equivalent of water equal to approximately 25% of  its total mass.
 +
** {{#Chem: Ca(OH)2  {  =  580°C} CaO + H2O}}
 +
** Calcium hydroxide can be converted  to calcium  carbonate by bubbling [[carbon dioxide]] through a solution/suspension of calcium hydroxide
 +
** {{#Chem: Ca(OH)2(aq) + CO2  = CaCO3 + H2O))
 +
 
==Synthesis==
 
==Synthesis==
 
===From calcium oxide===
 
===From calcium oxide===

Latest revision as of 17:09, 27 July 2020

 
Calcium hydroxide
Chemical formula Ca(OH)2
OTP appearance white solid 
Molar Mass(g/mol) 74.093 
Melting Point(°C) 580 (decomp) 
Density(g/cc) 2.211 
Enthalpy of Formation(kJ/mol) −987 
Solubility in water(g/L) 1.73 
Solubility in ethanol(g/L) non
NFPA 704
NFPA704.png
0
3
0
 

 

Thermal Decomposition
Calcium hydroxide
580°C
CaO,H2O

Uses

Primary

Secondary

  • Whitewash

Natural Occurrence

  • Calcium hydroxide does occur naturally as the rare mineral portlandite.

Hazards

  • Calcium hydroxide is alkaline. It can irritate the skin, eyes and lungs and should not be ingested in large quantities. Wash with fresh clean water after contact.

Character

  • Calcium hydroxide, calcium oxide, and calcium carbonate are three interconvertable calcium compounds.
    • Calcium hydroxide can be converted to calcium oxide by heating to 580°C, where it loses one molar equivalent of water equal to approximately 25% of its total mass.
    • Ca(OH)2
      {
      580°C}
      CaO + H2O
    • Calcium hydroxide can be converted to calcium carbonate by bubbling carbon dioxide through a solution/suspension of calcium hydroxide
    • {{#Chem: Ca(OH)2(aq) + CO2 = CaCO3 + H2O))

Synthesis

From calcium oxide

In ideal conditions (distilled water, pure calcium oxide) this works. Presuming a "part by mass" is 1g, this yields half a mol (37g) of calcium hydroxide.

  1. Gather a watertight container resistant to alkaline substances
  2. Gather 9 parts by mass of water
  3. Gather 28 parts by mass of calcium oxide
  4. Place the water in the container
  5. Slowly add the calcium oxide, allowing the water to cool in between additions
    CaO(s) + H2O(l) Ca(OH)2ΔH=−63.7 kJ/mol of Calcium
  6. The mixture is calcium hydroxide

Purification

Testing

Storage

  • Calcium hydroxide is a caustic alkali, so glass and ceramic containers are excellent. Aluminum in particular is bad.
  • Calcium hydroxide will absorb carbon dioxide from the air and precipitate as calcium carbonate, so keep in a sealed container

Disposal

See Also

References