What is the value of the gas constant R in units of L atm mol−1 K−1 used in the ideal gas law?

• A. 0.0821 L atm / (mol K)
• B. 8.314 L atm / (mol K)
• C. 62.364 L torr / (mol K)
• D. 0.082057 L atm / (mol K)

Answer: (D)

R acts as the bridge in PV = nRT, making pressure, volume, amount, and temperature fit together when pressure is in atmospheres and volume in liters. In those units, the constant must have the units L·atm·mol−1·K−1. The precise value is 0.082057 L atm mol−1 K−1, which is why this option is the best choice. A rounded version like 0.0821 is common for quick calculations, but it’s just a rounded form of the same constant. Other options use different unit systems or scales: 8.314 is in J·mol−1·K−1, not compatible with atm and L; 62.364 L·torr·mol−1·K−1 is the same constant expressed in torr units (1 atm = 760 torr). The value that exactly matches the requested units is 0.082057 L atm mol−1 K−1.