AP CHEMISTRY
WEEK 8
Study Guide
, AP CHEMISTRY
WEEK 8 STUDY GUIDE
Message to Lumist AP Learners
Hi AP Campers! Congratulations on making it to the final week of the Study Camp.
Our last unit is Applications of Thermodynamics. It covers about 7-9% of College
Board’s final exam.
We will begin our week by discussing entropy. This is commonly referred to as
disorder. According to physicists, all processes favor increasing entropy. This also means
that the entropy of the universe is always increasing! Chemical and physical processes
can still be favored when entropy decreases. We will explain this idea using Gibbs free
energy and enthalpy.
If entropy is favored, how has life, a highly ordered process, evolved? We will explain
how we can make biological reactions favorable through a process known as coupling.
This concept involves putting both favorable and unfavorable processes together.
This unit also looks at electrochemistry and equilibrium. For students who recently
joined the camp, it is recommended to review week 7 (equilibrium) and week 4 (redox
reactions) before attempting the problem set. Towards the end of the unit, we will
study electrochemical cells. This topic has a wide variety of applications since we live in
an electronic world. One important application of electrochemical cells is batteries.
This guide includes tips to help you avoid common misunderstandings and remember
key concepts. The end of this guide has a problem set with questions you can expect on
the exam. There is also a bonus question for students who want extra practice and a bit
of a challenge.
Good luck!
Chapter 8 Overview: Topics & Concepts
Applications of Thermodynamics (7-9% Final Exam Weighting)
1. Introduction to Entropy
Learning Objective 1: understand common definitions of entropy.
2
, AP CHEMISTRY
WEEK 8 STUDY GUIDE
Learning Objective 2: determine whether a reaction involves an increase (+) or decrease (-)
in entropy.
● Entropy is a difficult concept to understand. Some of the most common definitions of
entropy are the following:
● Entropy (S): disorder
● Entropy increases when energy/matter is dispersed.
● Entropy can also be understood by examining microstates. A microstate is a specific
configuration of all the particles and energies in a system.
● Consider the following example: imagine there are 4 balls of different colors. We need
to put the balls into 2 boxes. We can draw out all the possible combinations for this
scenario. The configuration where 2 balls are in each box has the highest probability.
Entropy will also favor the most probable configure which is also the most dispersed
microstate.
Phase Transitions & Entropy
● Entropy increases when matter is dispersed.
● Phase transitions are good examples of entropy changes. For example, going from a
solid to liquid or liquid to gas increases entropy because molecules can move more
freely. Gases have more entropy than solids or liquids.
Solid < Liquid < Gas
3
WEEK 8
Study Guide
, AP CHEMISTRY
WEEK 8 STUDY GUIDE
Message to Lumist AP Learners
Hi AP Campers! Congratulations on making it to the final week of the Study Camp.
Our last unit is Applications of Thermodynamics. It covers about 7-9% of College
Board’s final exam.
We will begin our week by discussing entropy. This is commonly referred to as
disorder. According to physicists, all processes favor increasing entropy. This also means
that the entropy of the universe is always increasing! Chemical and physical processes
can still be favored when entropy decreases. We will explain this idea using Gibbs free
energy and enthalpy.
If entropy is favored, how has life, a highly ordered process, evolved? We will explain
how we can make biological reactions favorable through a process known as coupling.
This concept involves putting both favorable and unfavorable processes together.
This unit also looks at electrochemistry and equilibrium. For students who recently
joined the camp, it is recommended to review week 7 (equilibrium) and week 4 (redox
reactions) before attempting the problem set. Towards the end of the unit, we will
study electrochemical cells. This topic has a wide variety of applications since we live in
an electronic world. One important application of electrochemical cells is batteries.
This guide includes tips to help you avoid common misunderstandings and remember
key concepts. The end of this guide has a problem set with questions you can expect on
the exam. There is also a bonus question for students who want extra practice and a bit
of a challenge.
Good luck!
Chapter 8 Overview: Topics & Concepts
Applications of Thermodynamics (7-9% Final Exam Weighting)
1. Introduction to Entropy
Learning Objective 1: understand common definitions of entropy.
2
, AP CHEMISTRY
WEEK 8 STUDY GUIDE
Learning Objective 2: determine whether a reaction involves an increase (+) or decrease (-)
in entropy.
● Entropy is a difficult concept to understand. Some of the most common definitions of
entropy are the following:
● Entropy (S): disorder
● Entropy increases when energy/matter is dispersed.
● Entropy can also be understood by examining microstates. A microstate is a specific
configuration of all the particles and energies in a system.
● Consider the following example: imagine there are 4 balls of different colors. We need
to put the balls into 2 boxes. We can draw out all the possible combinations for this
scenario. The configuration where 2 balls are in each box has the highest probability.
Entropy will also favor the most probable configure which is also the most dispersed
microstate.
Phase Transitions & Entropy
● Entropy increases when matter is dispersed.
● Phase transitions are good examples of entropy changes. For example, going from a
solid to liquid or liquid to gas increases entropy because molecules can move more
freely. Gases have more entropy than solids or liquids.
Solid < Liquid < Gas
3
