Which value of the gas constant R should be used when pressure is given in atmospheres (atm)?

• A. 8.314 J·mol^{-1}·K^{-1}
• B. 62.4 L·mmHg·mol^{-1}·K^{-1}
• C. 1.987 cal·mol^{-1}·K^{-1}
• D. 0.0821 L·atm·mol^{-1}·K^{-1}

Answer: (D)

Verified step by step guidance

1. Identify the units of pressure given in the problem, which is atmospheres (atm).
2. Recall that the gas constant R has different numerical values depending on the units used for pressure, volume, and energy.
3. Match the units of R to the units of pressure given. Since pressure is in atm, the value of R must include atm in its units.
4. Among the common values of R, the one with units L·atm·mol^{-1}·K^{-1} is appropriate when pressure is in atmospheres.
5. Therefore, the correct value of R to use when pressure is in atm is 0.0821 L·atm·mol^{-1}·K^{-1}.