Diffusion and Molecular Mass in Gases

Diffusion is a fundamental process where particles move from areas of higher concentration to areas of lower concentration. This movement occurs due to the random motion of particles, and it continues until a state of equilibrium is achieved, meaning the concentration of particles is uniform throughout the space. This principle is vital in various biological and physical processes, such as gas exchange in lungs and the mixing of substances in solutions.

In gases, particles are far apart and move freely at high speeds, leading to a rapid rate of diffusion. The large spaces between gas molecules allow them to spread out quickly and mix with other gases. In contrast, solids have tightly packed particles that can only vibrate in place, while liquids have more closely arranged particles that can slide past each other but still diffuse more slowly than gases. Thus, the nature of gas particles and their kinetic energy facilitates the fastest diffusion.

Diffusion rates depend on the state of matter. Gases have the fastest diffusion rates because their particles are widely spaced and move rapidly, allowing them to spread out quickly. Liquids have a slower diffusion rate than gases, as their particles are closer together and interact more, which hinders movement. Solids have the slowest diffusion rates due to their tightly packed particles that vibrate in fixed positions, making it difficult for them to move and diffuse. Thus, the order of diffusion rates is gas, followed by liquid, and then solid.

Diffusion is the process by which particles spread from areas of higher concentration to areas of lower concentration. This movement occurs due to the random motion of particles, driven by their kinetic energy. As particles collide and move in various directions, they naturally disperse throughout the available space, leading to an even distribution over time. This random movement is essential for the diffusion process, as it allows for the mixing of substances and the equalization of concentration gradients.

Graham's law of effusion states that the rate of diffusion of a gas is inversely proportional to the square root of its molecular mass. This means that heavier gases, which have larger molecular masses, will diffuse more slowly compared to lighter gases. As a result, when comparing two gases, the one with the larger molecular mass will take longer to spread out or move through a medium than the one with a smaller molecular mass, confirming the statement as true.

The relative molecular mass of ammonia (NH₃) is calculated by summing the atomic masses of its constituent elements. Nitrogen (N) has an atomic mass of approximately 14, while hydrogen (H) has an atomic mass of about 1. Since ammonia consists of one nitrogen atom and three hydrogen atoms, the calculation is as follows: 14 (for N) + 3 × 1 (for H) = 14 + 3 = 17. Thus, the relative molecular mass of NH₃ is 17.

O₂, or molecular oxygen, consists of two oxygen atoms. The atomic mass of a single oxygen atom is approximately 16. Therefore, to find the relative molecular mass of O₂, you multiply the atomic mass of oxygen (16) by the number of oxygen atoms in the molecule (2). This calculation yields 16 x 2 = 32. Thus, the relative molecular mass of O₂ is 32.

Ammonia (NH₃) diffuses faster than oxygen (O₂) because it has a lower molecular mass. According to Graham's law of effusion, lighter gases diffuse more rapidly than heavier ones. Ammonia has a molecular mass of about 17 g/mol, while oxygen has a molecular mass of approximately 32 g/mol. This difference in mass means that ammonia molecules move more quickly and can spread out more rapidly in a given space compared to the heavier oxygen molecules, leading to faster diffusion.