Methane
Properties
| State | Gas at room temperature (odorless; commercial gas has added odorant) |
| Color | Colorless |
| Solubility | Slightly soluble in water (22 mg/L at 25°C) |
| Melting Point | -182.5°C |
| Boiling Point | -161.5°C |
About Methane
Methane is the simplest alkane and the molecule that runs about a quarter of global energy: pipeline natural gas, LNG cargoes, and the gas-fired turbines that handle peak load on most modern grids. CH4 is a perfect tetrahedron — sp³ carbon with four equivalent C-H bonds at 109.5°, bond length 1.087 Å, bond energy 439 kJ/mol — and that high C-H bond strength is exactly why methane is so unreactive at room temperature and why it has to be combusted at high temperature or activated catalytically to be useful. The combustion thermochemistry is favorable: CH4 + 2O2 → CO2 + 2H2O, ΔH = -890 kJ/mol, and per mole of CO2 emitted you get more energy than from any other fossil fuel (55.5 kJ/g of CH4 vs ~32 for coal, ~44 for diesel). That higher H:C ratio is why utilities switching from coal to natural gas was the single biggest factor in flattening US power-sector CO2 emissions over 2008-2020. The flip side is the climate problem: methane is roughly 80x more potent than CO2 as a greenhouse gas on a 20-year time horizon (GWP-20 ≈ 80, GWP-100 ≈ 28), and pipeline leaks, fugitive emissions from upstream production, and enteric fermentation in cattle (something like 95 Tg/yr from livestock) make tracking and plugging leaks a major mitigation lever. Industrially, methane is the feed for steam methane reforming (CH4 + H2O → CO + 3H2) — the dominant industrial source of H2 — and for the Haber-Bosch ammonia chain that fertilizes much of the world's grain.
Where you'll encounter it
If you have ever lit a stovetop burner, watched the flame turn from yellow to clean blue as the air shutter opens, you have run a controlled methane combustion at around 1950°C with a stoichiometric equivalence ratio near 1.0. The mercaptan smell — t-butyl mercaptan or ethyl mercaptan, added at parts-per-million levels because pure methane is odorless — is the only thing that lets you find a leak before it accumulates to the 5% lower flammability limit. In a chemistry lab, you encounter methane two ways: as the textbook diagram for sp³ hybridization in week one of organic chemistry, and as the bubbling output when you drop a piece of CaC2 in water to make acetylene — methane shows up as a side product depending on the carbide quality. In the field, environmental scientists with handheld FTIR units track ppm-level fugitive emissions over wells and pipelines; the same molecule shows up in atmospheric IR spectra at 3.3 µm and 7.7 µm, the two strong absorption bands that drive its outsized greenhouse effect.
Common Uses
- Pipeline natural gas for residential heating, cooking, and industrial process heat
- Combined-cycle gas turbine fuel for grid electricity generation
- Steam methane reforming feedstock for ~95% of industrial H2 production
- Compressed natural gas (CNG) and LNG for heavy-duty trucking and marine fuel
- Chemical feedstock for methanol, formaldehyde, carbon black, and chlorinated methanes
Safety Information
GHS: Flammable gas (Category 1, H220), Compressed gas (H280). Extremely flammable; explosive limits in air 5-15% v/v. Simple asphyxiant — displaces O2 in confined spaces with no warning since pure methane is odorless. No inhalation exposure limit applies, because methane is not toxic — the controlling hazard is oxygen displacement, so confined spaces need atmosphere monitoring for oxygen deficiency. Pipeline natural gas contains added mercaptan odorant detectable at ~1% of the LEL. Auto-ignition temperature 537°C, flash point -188°C. Respect ignition sources around any leak. CH4 is potent greenhouse gas (GWP-100 ≈ 28, GWP-20 ≈ 80) — fugitive-emission monitoring required at production sites under EPA Subpart W. Cryogenic LNG handling adds frostbite and embrittlement hazards.
This safety summary is for educational reference only and may not be complete. It is not a substitute for Safety Data Sheets (SDS), medical advice, or professional chemical safety guidance. Always consult appropriate SDS and qualified professionals before handling chemicals. We deliberately do not publish occupational exposure limits or other regulatory thresholds: those values are revised over time and differ between jurisdictions, so the only correct source is the current SDS and the regulations that apply where you work.