what is the specific heat of methane?
The correct answer and explanation is:
Correct Answer:
The specific heat capacity of methane (CH₄) depends on the conditions (constant pressure or constant volume):
- At constant pressure (Cp):
≈ 2.22 J/g·°C or 35.69 J/mol·K - At constant volume (Cv):
≈ 1.74 J/g·°C or 27.29 J/mol·K
300-Word Explanation:
Specific heat capacity is the amount of heat required to raise the temperature of a unit mass of a substance by one degree Celsius (or one Kelvin). For methane (CH₄), a simple hydrocarbon gas, this value varies slightly depending on pressure, temperature, and whether the measurement is taken at constant pressure (Cp) or constant volume (Cv).
Methane is commonly encountered as a gas under standard temperature and pressure. It is the primary component of natural gas and is widely used as a fuel. Its specific heat is measured in joules per gram per degree Celsius (J/g·°C) or in joules per mole per Kelvin (J/mol·K).
At constant pressure, where the gas can expand, methane has a higher specific heat capacity (~2.22 J/g·°C). This is because, in addition to increasing its internal energy, the gas also does work by expanding against the surrounding pressure. Thus, more heat is needed.
At constant volume, the gas cannot expand, so all the heat goes into increasing its internal energy, resulting in a slightly lower specific heat (~1.74 J/g·°C).
The molar specific heat values (per mole rather than per gram) are often used in chemistry and thermodynamics. For methane, Cp ≈ 35.69 J/mol·K, and Cv ≈ 27.29 J/mol·K. These values are derived using the principles of kinetic theory and molecular degrees of freedom.
Understanding methane’s specific heat is essential in various fields such as chemical engineering, combustion analysis, and climate science, where accurate energy calculations are necessary for system design, fuel efficiency, and environmental modeling.