Solid phase
Official name
metastable Acetylene ice
Secondary names
C2H2 ice; Acetylene ice; metastable C2H2
Type
Family
molecular solid
Class
non polar molecular solid
Compound type
organic molecular solid
Chemical composition
Formula
$C_2H_2$
Chemical formula
C2H2
Elemental formula
C2 H2
Isotope mixture type
terrestrial abundance
2.0
  Formula Name Family Number min-max Mole fraction Isotope mole fraction State Relevance
$C_2H_2$ Ethyne molecule 1 1.0 1 pure main
Chemical functions
  Function Number
$R\equiv CH$ 2
Chemical bonds
  Bond Number
$\equiv C-H$ 2
$-C\equiv C-$ 1
Class
molecular solids with apolar molecules (01)
Type
with polyatomic organic apolar molecules (CnHm...) (01.06)
Equivalent liquid
liquid acetylene
Phase name
metastable C2H2
Phase type
disordered
Crystal system
unknown
Molar mass
26.037 $g/mol$
State NTP
gas
Phase transitions
Phase transition type Other phases Temperature - Pressure
solid-solid to C2H2-II ice above ~65 $\pm$5K
solid-solid from amorphous C2H2 ice above ~45 $\pm$3K
Phase transitions comments
irreversible transitions from amorphous phase and to phase II. Seem to form by condensation in the ~25-35K range (cf. Fig 5 Hudson et al. 2014)
Refringence type
unknown
Refraction index $n_{\alpha}$
1.18 - 1.23
Pure color
colorless
Diaphaneity
transparent to translucent
Luster
vitreous