Chapter 18, Problem 1Q

Why doesn’t the size of different molecules enter into the ideal gas law?

To determine

The reason for the size of different molecules not being considered in ideal gas law.

Answer to Problem 1Q

The size of the molecule is not considered for the different molecules because the average distance between the molecules is far greater than the size of the molecules.

Explanation of Solution

The ideal gas law is defined based on the several basic postulates of the kinetic theory of gases. One of the postulates states that the molecules present in a closed container are sufficiently far enough from each other to consider their size on average.

Therefore, the size of the molecules is not considered as a prime factor in defining the ideal gas law. The ideal gas law considers the average size of all the molecules present in the closed container as they are comparably far away from each other as compared to their diameter.

So, this postulate eliminates the need for the size of the different molecules present it container. It rather uses the average size of molecules for the whole lot of the molecules present.

Conclusion:

Thus, the size of the molecule is not considered for the different molecules because the average distance between the molecules is far greater than the size of the molecules.