Compare how entropy changes for the following two systems: System A: Two gases mix when the valve separating two containers is opened.

System B: A solid powder decomposes to form a solid product and a gas product.

The entropy in system A is more than the entropy in system B.

Explanation:

The degree of randomness present in the atoms of a substance is called entropy.

In system A, two gases mix when the valve separating two containers is opened. This means that number of molecules are increasing due to which collisions will also increase.

As a result, entropy will tend to increase in system A.

In system B, solid powder decomposes to form a solid product and a gas product. As atoms of a solid are attached together due to more force of attraction so there will be no randomness in a solid substance. But gas is also forming and there exists weak forces between molecules of a gas.

Hence, randomness is more in a gas as compared to solid substance.

Therefore, we can conclude that entropy in system A is more than the entropy in system B.