The specific gravity of methane is calculated by dividing the molecular weight of methane by the molecular weight of air.
Here's a breakdown of how to calculate the specific gravity of methane:
Understanding Specific Gravity
Specific gravity is a dimensionless quantity that represents the ratio of the density of a substance to the density of a reference substance. For gases, the reference substance is typically air. It indicates how much heavier or lighter a gas is compared to air.
Calculation
The specific gravity of methane is determined using the following formula:
Specific Gravity of Methane = (Molecular Weight of Methane) / (Molecular Weight of Air)
- Molecular Weight of Methane (CH₄): 16.04 g/mol
- Molecular Weight of Air: Approximately 28.97 g/mol
Therefore:
Specific Gravity of Methane = 16.04 / 28.97 ≈ 0.55
Interpretation
A specific gravity of 0.55 indicates that methane is lighter than air. This is why methane, when released into the atmosphere, tends to rise.
Variations
While pure methane has a specific gravity of approximately 0.55, natural gas reservoirs often contain other hydrocarbons. The presence of heavier hydrocarbons (like ethane, propane, and butane) will increase the overall specific gravity of the gas mixture. A "rich" or "heavy" natural gas reservoir can have a specific gravity of 0.75 or even higher in rare cases, exceeding 0.9. This indicates a higher concentration of heavier hydrocarbons.
In summary, the specific gravity of pure methane is approximately 0.55, calculated by dividing the molecular weight of methane by the molecular weight of air. The specific gravity of natural gas can vary depending on the composition of the gas mixture.
