Certified Flight Registered Nurse (CFRN) Practice Exam

Which gas law relates to the diffusion rate of a gas through a membrane relative to its molar mass?

1. Boyle's law

2. Henry's law

3. Graham's law

4. Dalton's law

The correct answer is: Graham's law

The correct answer is Graham's law, which specifically addresses the diffusion rates of gases and how they relate to their molar masses. According to Graham's law, the rate of diffusion of a gas is inversely proportional to the square root of its molar mass. This means that lighter gases will diffuse more quickly than heavier gases. This principle is essential in understanding how different gases behave when encountering barriers, such as membranes. For instance, if two gases are allowed to diffuse through a membrane, the lighter gas will pass through more rapidly than the heavier gas, illustrating the direct application of Graham's law in real-world scenarios, such as respiration in biological systems or gas exchange in industrial processes. The other gas laws provided have different focuses: Boyle's law pertains to the relationship between pressure and volume at a constant temperature, Henry's law relates to the solubility of gases in liquids under pressure, and Dalton's law addresses the partial pressures of gases in a mixture. None of these laws specifically address the relationship between diffusion rates and molar mass, making Graham's law the definitive choice for this question.