Enthalpy And Entropy

Question 0

What is the difference of entropy between a solid and a liquid?

Answer 0

Solid has the lowest entropy, liquid had a higher entropy as it is more disordered (then gas)

Question 1

What is entropy?

Answer 1

A measure of the ‘disorder’ of a system and that a system becomes energetically more stable when it becomes more disordered.

Question 2

What happens to the entropy when a solid lattice dissolves?

Answer 2

The entropy increases - more disorder

Question 3

What is the change of entropy in a reaction where there is a change in the number of gaseous molecules?

Answer 3

If more gaseous molecules, entropy increases because disorder increases

Question 4

How do we calculate the entropy change for a reaction?

Answer 4

Entropy= sum of standard entropy of products - sum of standard enthalpy of reactants

Question 5

What happens to S if a change makes a system more random?

Answer 5

S is positive.

Question 6

What happens to S if a change makes the system more ordered?

Answer 6

S is negative.

Question 7

What does the tendency of a process to take place depend on?

Answer 7

• temperature
• entropy change in the system
• enthalpy change with the surroundings

Question 8

What is free energy change?

Answer 8

The balance between entropy and enthalpy, which determines the feasability of a reaction.

Question 9

Equation for free energy change

Answer 9

DeltaG=deltaH-TdeltaS

Question 10

How are endothermic reactions able to take place spontaneously?

Answer 10

DeltaS must be positive
The temperature must be high enough that TdeltaS is greater than deltaH
Only some endothermic reactions take place spontaneously at rtp