Chemistry - Entropy Changes in Physical Processes

[ncm2]

Homework Statement

Indicate how entropy of the system changes for each of the physical processes shown below.
Entropy increases, entropy decreases, entropy does not change.

1. Purification
2. Mixing
3. Freezing
4. Evaporation
5. Separation

Homework Equations

Entropy increases when it goes from less to more disorder.
Entropy decreases when it goes from more to less disorder.

The Attempt at a Solution

Purification - many to one substance, so entropy decreases
Mixing - many to one substance, so entropy decreases
Freezing - more to less disorder, so entropy decreases
Evaporation - less to more disorder, so entropy increases
Separation - one to many substances, so entropy increases

These are wrong, but I can't think of why. Help is much appreciated.

 

[Borek]

Mixing - many to one substance... Do you mean that solution is ONE SUBSTANCE? What do you mean by one substance?

 

[Blueshift5]

Your responses are mostly correct, but there are a few corrections that can be made.

1. Purification - In this process, the system goes from a mixture of substances to a pure substance. This means that the disorder of the system decreases, so entropy decreases.
2. Mixing - In this process, the system goes from two or more substances to a mixture. This means that the disorder of the system increases, so entropy increases.
3. Freezing - In this process, the system goes from a liquid state to a solid state. This means that the disorder of the system decreases, so entropy decreases.
4. Evaporation - In this process, the system goes from a liquid state to a gas state. This means that the disorder of the system increases, so entropy increases.
5. Separation - In this process, the system goes from a mixture to two or more pure substances. This means that the disorder of the system increases, so entropy increases.