Which value is correct for the Ideal Gas Constant R when using liters, atmospheres, moles, and kelvin?

Which value is correct for the Ideal Gas Constant R when using liters, atmospheres, moles, and kelvin?

• A. 0.0821 L·atm/(mol·K)
• B. 8.31 L·kPa/(mol·K)
• C. 1.987 cal/(mol·K)
• D. 62.36 L·mmHg/(mol·K)

Answer: (A)

PV = nRT links pressure, volume, amount, and temperature, so R must match the units used. With pressure in atmospheres, volume in liters, amount in moles, and temperature in kelvin, R is 0.0821 L·atm/(mol·K). This value keeps the equation consistent, and you can sanity-check it by noting that at 1 atm and 298 K, one mole would occupy about 24.5 L (V = nRT/P ≈ 1×0.0821×298 / 1 ≈ 24.5 L). The other numbers correspond to different pressure or energy units (8.31 for kPa, 1.987 for calories, 62.36 for mmHg), but not the specified set of units.

PV = nRT links pressure, volume, amount, and temperature, so R must match the units used. With pressure in atmospheres, volume in liters, amount in moles, and temperature in kelvin, R is 0.0821 L·atm/(mol·K). This value keeps the equation consistent, and you can sanity-check it by noting that at 1 atm and 298 K, one mole would occupy about 24.5 L (V = nRT/P ≈ 1×0.0821×298 / 1 ≈ 24.5 L). The other numbers correspond to different pressure or energy units (8.31 for kPa, 1.987 for calories, 62.36 for mmHg), but not the specified set of units.