ACS Chemistry Practice Exam 2025 – The All-in-One Guide to Exam Success!

In the context of gas laws and thermodynamics, the ideal gas law is often expressed in the equation PV = nRT, where P is pressure, V is volume, n is the number of moles, R is the ideal gas constant, and T is temperature. When dealing with measurements in liters, atmospheres, and moles per Kelvin, the value of R that is particularly relevant is 0.0821 L·atm/(mol·K).

This specific value of R allows for calculations involving the volume of gas at a given pressure and temperature using the ideal gas law. It is commonly used in chemistry laboratories and applied in various calculations dealing with gases under ideal conditions.

The other values listed correspond to different units or contexts. For example, 8.3145 J/(mol·K) is the value of R when energy is expressed in joules, and 1.987 cal/(mol·K) is used in calorimetric processes. Therefore, the value of R that aligns with liters and atmospheres per mole Kelvin is 0.0821, making it the appropriate choice for this context.