Solid phase
Official name
alpha Carbon Monoxide
Secondary names
alpha-CO
Type
Family
molecular solid
Class
polar molecular solid
Compound type
inorganic molecular solid
Chemical composition
Formula
$\alpha-CO$
Chemical formula
CO
Elemental formula
C O
Isotope mixture type
terrestrial abundance
2.0
  Formula Name Family Number min-max Mole fraction Isotope mole fraction State Relevance
$CO$ Carbon monoxide molecule 1 1.0 1 pure main
Chemical bonds
  Bond Number
$C^-\equiv O^+$ 1
Class
molecular solids with polar molecules (02)
Type
with polyatomic inorganic polar molecules (02.02)
Group
with chalcogens (02.02.03)
Phase name
$\alpha-CO$
Phase type
crystalline
Crystal system
isometric (cubic)
Crystal class
tetartoidal
Crystal class symbol
23 (T)
Crystal spacegroup
P2(1)3
Crystal molecule sites
Label Type Nb Species Species coordinence Species occupancy Species order
S6 main 4  $CO$ 1.0 fixed position
Comments
order-disorder phase transition around 30-35K (head-to-tail reorientation of CO)
Molar mass
28.01014082 $g/mol$
Density
1.0394 @14K to 0.983 @62.5K $g/cm^3$
State NTP
gas
Phase transitions
Phase transition type Other phases Temperature - Pressure
solid-solid beta-CO 61.6K
solid-solid epsilon-CO 3.7-3.85GPa (0 to 125K)
solid-solid delta-CO 3.85 GPa (125K) to 3.9GPa (~155K)
Refringence type
isotropic
Pure color
colorless
Diaphaneity
transparent
Luster
vitreous
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