Input interpretation
propadiene
Chemical names and formulas
formula | H_2C=C=CH_2 Hill formula | C_3H_4 name | propadiene IUPAC name | allene alternate names | 1, 2-propadiene | allene | dimethylenemethane | propa-1, 2-diene | sym-allylene mass fractions | C (carbon) 89.9% | H (hydrogen) 10.1%
Lewis structure
Draw the Lewis structure of propadiene. Start by drawing the overall structure of the molecule, ignoring potential double and triple bonds: Count the total valence electrons of the carbon (n_C, val = 4) and hydrogen (n_H, val = 1) atoms: 3 n_C, val + 4 n_H, val = 16 Calculate the number of electrons needed to completely fill the valence shells for carbon (n_C, full = 8) and hydrogen (n_H, full = 2): 3 n_C, full + 4 n_H, full = 32 Subtracting these two numbers shows that 32 - 16 = 16 bonding electrons are needed. Each bond has two electrons, so in addition to the 6 bonds already present in the diagram add 2 bonds. To minimize formal charge carbon wants 4 bonds. Identify the atoms that want additional bonds and the number of electrons remaining on each atom: Fill in the 2 bonds by pairing electrons between adjacent highlighted atoms: Answer: | |
3D structure
3D structure
Basic properties
molar mass | 40.065 g/mol phase | gas (at STP) melting point | -136 °C boiling point | -34 °C density | 1.787 g/cm^3 (at 20 °C) solubility in water | slightly soluble
Units
Gas properties (at STP)
density | 1.787 g/cm^3 (at 20 °C) vapor density | 1.42 (relative to air) molar volume | 22.42 cm^3/mol refractive index | 1.4168
Units
Thermodynamic properties
specific heat of formation Δ_fH° | gas | 4.755 kJ/g molar heat of formation Δ_fH° | gas | 190.5 kJ/mol molar heat of vaporization | 21.4 kJ/mol | specific heat of vaporization | 0.534 kJ/g | molar heat of combustion | 1946 kJ/mol | specific heat of combustion | 48.57 kJ/g | molar heat of fusion | 4.4 kJ/mol | specific heat of fusion | 0.11 kJ/g | critical temperature | 394 K | critical pressure | 5.25 MPa | (at STP)
Chemical identifiers
CAS number | 463-49-0 Beilstein number | 1730774 PubChem CID number | 10037 PubChem SID number | 24857749 SMILES identifier | C=C=C InChI identifier | InChI=1/C3H4/c1-3-2/h1-2H2 MDL number | MFCD00008566
NFPA label
NFPA label
NFPA health rating | 2 NFPA fire rating | 4 NFPA reactivity rating | 2
Safety properties
flash point | -96 °C lower explosive limit | 2.1% (concentration in air) upper explosive limit | 17% (concentration in air)
DOT hazard class | 2.1 DOT numbers | 2200