As a chemical expert with a deep understanding of the properties of various substances, including methane, I can provide a comprehensive answer to the question of whether methane is flammable as a liquid.

Methane, CH4, is a hydrocarbon and the primary component of natural gas. It is known for its flammability and is widely used as a fuel source. Under standard conditions on Earth, methane is a colorless, odorless gas. The flammability of a substance is determined by its ability to react with oxygen to produce a flame. This reaction is known as combustion.

On Earth, the atmosphere contains approximately 21% oxygen, which is necessary for combustion to occur. Methane can easily ignite in the presence of oxygen and an ignition source, such as a spark or flame. However, the question specifically asks about the flammability of methane in its liquid state.

The flammability of a substance does not change based on its state of matter; rather, it is an inherent property of the substance itself. However, the conditions under which it burns can vary. For methane to be in a liquid state, it must be subjected to high pressures and low temperatures. The critical temperature of methane, which is the temperature above which it cannot be liquefied regardless of pressure, is -82.6°C (-117.7°F). Below this temperature, methane can be liquefied under the right conditions of pressure.

Now, considering the scenario on Titan, one of Saturn's moons, the conditions are vastly different from those on Earth. Titan's atmosphere lacks the oxygen necessary for combustion, and the extremely low temperatures allow methane to exist in a liquid state. The surface temperature of Titan is around -179°C (-290°F), which is well below the critical temperature of methane, allowing it to form lakes and seas of liquid methane.

However, the absence of oxygen on Titan means that even though methane is present in a liquid state, it cannot undergo combustion in the same way it does on Earth. Combustion requires a fuel, an oxidizer (oxygen in this case), and an ignition source. Without the oxidizer, the methane on Titan would not burn, regardless of whether it is in a liquid or gaseous state.

In summary, while methane is inherently flammable due to its chemical composition, the environmental conditions must support combustion. On Earth, where oxygen is abundant, methane is flammable both as a gas and, theoretically, as a liquid if the conditions for combustion are met. On Titan, despite methane being present in a liquid state, the lack of oxygen in the atmosphere prevents it from being flammable.

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On Earth, methane is a flammable gas, but Titan has no oxygen in its atmosphere that could support combustion. Also, the temperatures on Titan are so cold -- minus 300 degrees Fahrenheit (minus 149 degrees Celsius) -- that the methane can form liquid.Jul 27, 2006read more >>