What is the value of the gas constant R?

What is the value of the gas constant R?

• A. 0.00831 J/(K·mol)
• B. 8.31 kJ/(K·mol)
• C. 8.31 J/(K·mol)
• D. 83.1 J/(K·mol)

Answer: (C)

R is the universal gas constant that links pressure, volume, temperature, and amount in the ideal gas law PV = nRT. In SI units, its value is 8.314 J/(mol·K), which is the energy per mole per kelvin. Because 1 J equals 1 Pa·m^3, you can also express it as 8.314 Pa·m^3/(mol·K) or 8.314 L·kPa/(mol·K). Rounded for simplicity, it is commonly taken as 8.31 J/(mol·K). The correct value is not 0.00831 J/(mol·K) (that's off by a factor of 1000), nor 8.31 kJ/(mol·K) (off by a factor of 1000 in the other direction), nor 83.1 J/(mol·K) (off by a factor of about 10).

R is the universal gas constant that links pressure, volume, temperature, and amount in the ideal gas law PV = nRT. In SI units, its value is 8.314 J/(mol·K), which is the energy per mole per kelvin. Because 1 J equals 1 Pa·m^3, you can also express it as 8.314 Pa·m^3/(mol·K) or 8.314 L·kPa/(mol·K). Rounded for simplicity, it is commonly taken as 8.31 J/(mol·K).

The correct value is not 0.00831 J/(mol·K) (that's off by a factor of 1000), nor 8.31 kJ/(mol·K) (off by a factor of 1000 in the other direction), nor 83.1 J/(mol·K) (off by a factor of about 10).