Entropy

Question 1

What is entropy?

Answer 1

Measure of how disordered or chaotic a system is

Question 2

What does an increase in entropy do?

Answer 2

Makes the system more energetically stable

CaCO3(s) → CaO(s) + CO2(g)

CO2 gas more disordered than solid CaCO3, so entropy increased

Question 3

What does ice melting have to do with entropy?

Answer 3

• Ice is solid, so H2O molecules vibrate in fixed positions
• In water particles are arranged more randomly
• So water is more disordered
• Hence when ice melts the entropy of the system increases

Question 4

2nd law of thermodynamics

Answer 4

Entropy of universe always increases :

• Cups fall of tables and break, never other way around
• Hot objects cool and spread heat to surroundings
• Living things die and decompose into simpler molecules

Question 5

Calculating entropy changes

Answer 5