What's NEW at The Physics Classroom?
We've been at this task of providing students, teachers, and classrooms high-quality, ready-to-use resources for a long time. And we are as passionate about it now as we were 29 years ago when we started. We are always working on something new. But it is such a big website that the new additions often get nested deep inside of a section and are never noticed for months or even years after being published. So we're aiming to fix that problem with this page of announcements. Visit this page to find out about our most recent additions. And check back often in anticipation of finding new surprises.
November, 2025
November 21, 2025
Chemistry Tutorial - Batteries and Commercial Cells
We have completed the second of three lessons in our
Electrochemistry chapter. Our newest page is titled
Batteries and Commercial Cells. Different battery types rely on different materials and reaction pathways, but they all operate on the same principle: spontaneous redox reactions that create a flow of electrons and produce usable voltage. This page explains the details behind alkaline dry cells, lead-acid storage batteries, and lithium-ion batteries.
November 19, 2025
Chemistry Tutorial - Cell Potential
We have completed the third of four pages in Lesson 2 of our
Electrochemistry chapter. Our newest page is titled
Cell Potential. Galvanic cells generate a cell voltage due to the difference in reduction potential for the two half cells. This page explains how to analyze a galvanic cell and determine its cell voltage for both standard and non-standard conditions.
Physics Tutorial - Magnetic Induction - Flux and Faraday’s Law
We have completed the the four pages in Lesson 1 of our new
Magnetic Induction chapter. These four lessons introduct Electromagnetic Induction, Magnetic Flux and it's calculation, Faraday's Law in calculating Electromagnetic Force changes and Lenz's Laws in determining the direction of the induced current.
November 18, 2025
Chemistry Tutorial - Reference Section: Standard Reduction Potential
The Reference section of our Chemistry Tutorial includes a collection of tables, data, and other data needed by teachers and students in an introductory Chemistry course. We have just uploaded a table of standard reduction potential values for a variety of half-cells.
November 17, 2025
Chemistry Tutorial - Reduction Potential
Lesson 2 of our
Electrochemistry chapter continues to grow. We have published a new page titled
Reduction Potential. Reduction potentials reveal how strongly a substance attracts electrons. Our newest page explains how these values can be used to predict which substances get reduced, which get oxidized, and the direction of electron flow in any electrochemical cell.
November 14, 2025
Chemistry Tutorial - What is a Galvanic Cell?
We have begun Lesson 2 of our
Electrochemistry chapter with the publication of
What is a Galvanic Cell?. Galvanic cells operate because oxidation and reduction occur in separate locations, forcing electrons through an external circuit. This page explains the roles of the anode, cathode, and the salt bridge and discusses the various ways of representing a galvanic cell.
November 13, 2025
Curriculum Corner - Solutions Equilibria Unit
We have just uploaded eight new Think Sheets for our
Solutions Equilibria Unit of the Curriculum Corner. Think Sheets coordinate with our Tutorial pages on the same topic. They serve as useful in-class practice of chemistry concepts and mathematical relationships. Best of all: they can be downloaded for free. Think Sheets for
all Chemistry topics can be found on the main page of the Curriculum Corner section.
November 12, 2025
Chemistry Tutorial - Balancing Redox Reactions
We have completed our final page of Lesson 1 of our
Electrochemistry chapter with the publication of
Balancing Redox Reactions. The use of the half-reaction method to balance redox reactions is explained and demonstrated through numerous examples and with elaborate detail. A Check Your Understanding section provides students with independent practice and a chance to check their work and correct mistakes.
November 11, 2025
Chemistry Tutorial - Oxidation States
We have completed our second page of Lesson 1 of our
Electrochemistry chapter with the publication of
Oxidation States. We explain how oxidation states are the bookkeeping system of electrochemistry that reveal how electrons transfer during chemical reactions and help us to identify which substances are oxidized and reduced.
November 10, 2025
Chemistry Tutorial - Oxidation and Reduction
We have completed our first page of Lesson 1 of our
Electrochemistry chapter with the publication of
Oxidation and Reduction. Understanding oxidation and reduction reactions is essential in electrochemistry. This page explains how electrons are transferred and why some substances act as oxidizing or reducing agents.
November 7, 2025
Friday Fixes
Over the past couple of weeks we have been editing some of our Task-Tracker compatible Interactives. One feature of these interactives is that teachers with Task Tracker accounts can discard a desired number of question groups so that they are not presented to their students. The code was not working properly and discarding more question groups than selected by teachers. We have modified the code for about 13 applicable interactives. Updates were published this week.
Chemistry Tutorial - Electrochemistry Chapter
We have developed a tentative outline for Chapter 18, our
Electrochemistry chapter. Our pages should begin appearing this coming week and the chapter should be completed by Thanksgiving.
November 6, 2025
Chemistry Tutorial - Gibbs Free Energy and Equilibrium
We have completed our final page of Lesson 3 of our
Thermodynamics chapter with the publication of
Gibbs Free Energy and Equilibrium. The page explains how the balance between reactants and products at equilibrium can be understood through Gibbs free energy. The sign and magnitude of ΔG° reveal whether a reaction favors products or reactants and how it relates to the equilibrium constant K. This marks the end of Chapter 17. Our Chapter 18 pages will begin appearing next week.
November 5, 2025
Study Cards for Solutions Equilibrium Chapter of Chemistry Tutorial
All nine Study Cards for Chapter 16 have been completed and published. The final Study Cards can be found on the following pages. Scroll to the bottom and tap on the link in the Before You Leave section:
November 4, 2025
Study Cards for Solutions Equilibrium Chapter of Chemistry Tutorial
We have begun the creation of Study Cards for Chapter 16. Study Cards are useful review tools for students who rely on our Chemistry Tutorial as their main outside-of-class reference. They would serve as an excellent review in preparation for quizzes and tests. They are brief, visual, to-the-point, amd accompanied by a QR code and navigation information for easily finding the original source. The first three of nine Study Card uploads can be found on these pages:
The Solubility Product Constant, Ksp ||
Solubility and Ksp ||
Solubility and Common Ion Effects
November 1, 2025
Chemistry Tutorial - Predicting Spontaneity with Gibbs Free Energy
We have completed our first page of Lesson 3 of our
Thermodynamics chapter with the publication of
Predicting Spontaneity with Gibbs Free Energy. The page emphasizes that the Gibbs free energy equation provides a single numerical indicator (ΔG) for predicting whether a reaction at constant pressure and temperature can proceed spontaneously. Readers will learn how to use enthalpy change (ΔH) and the T•ΔS term to determine the spontaneity of a reaction.
October, 2025
October 30, 2025
Chemistry Tutorial - The Second Law of Thermodynamics
We have completed Lesson 2 of our
Thermodynamics chapter with the publication of
The Second Law of Thermodynamics. Spontaneous changes are driven by the spread of matter and energy. The Second Law of Thermodynamics associates the entropy changes of both the system and the surroundings to matter spread and energy spread, providing a reliable means of predicting whether a process will occur spontaneously. This page explains all.
October 29, 2025
Chemistry Tutorial - The Mathematics of Entropy Change
We have published our third page Lesson 2 of our newest Chemistry Tutorial chapter on
Thermodynamics. Our most recent page, titled
The Mathematics of Entropy Change, demonstrates how chemists use standard molar entropies and the Third Law of Thermodynamics to calculate
ΔS for a system undergoing change, helping to explain the driving forces behind spontaneous change.
October 28, 2025
Study Cards for Acids and Bases Chapter of Chemistry Tutorial
October 27, 2025
Study Cards for Acids and Bases Chapter of Chemistry Tutorial
We have begun creation of Study Cards for Chapter 15. We intend Study Cards to be a useful review tool for students who rely on our Chemistry Tutorial as their main outside-of-class reference. They would serve as an excellent review in preparation for quizzes and tests. Each Study Card has a QR code and navigation information for easily finding the original source. Our first five of 12 Study Card uploads can be found on these pages:
Properties of Acids and Bases |
Models of Acids and Bases
Water and its Ionization |
The pH Scale |
pH Indicators
Links to Study Cards are found in the Before You Leave section near the bottom of each page.
October 22, 2025
Chemistry Tutorial Reference Page - Standard Entropy Values
We added a new page to the Reference section of our Chemistry Tutorial. It includes standard entropy values for nearly 1000 substances. Looking for a value? We probably have it.
October 16, 2025
Chemistry Tutorial - What is Entropy?
We have published our second page Lesson 2 of our newest Chemistry Tutorial chapter on
Thermodynamics. Our most recent page, titled
What is Entropy?, explains why entropy increases when matter and energy spread out. Melting, vaporizing, warming, and mixing all lead to more dispersal of particles, which means more entropy. This increase reflects the greater number of ways the system can be arranged, making high-entropy states more probable than low-entropy ones.
October 14, 2025
Chemistry Tutorial - Driving Forces for Change
We have started Lesson 2 of our newest Chemistry Tutorial chapter on
Thermodynamics. Our most recent page, titled
Driving Forces for Change, explains how every spontaneous process is guided by forces that push energy and matter toward more dispersed states. These driving forces set the stage for understanding entropy and why change happens.
October 13, 2025
Chemistry Tutorial - Chapter 14 Fine Tuning
We have done some significant fine tuning of our
Kinetics and Equilibrium Chapter in our Chemistry Tutorial. We have improved our section headings, added ALT tags to all images, and tailored our meta-data for search engines. While this has little impact upon the user experience, it does (hopefully) improve our rank among search engines such that they display more frequently in common student searches.
October 9, 2025
Chemistry Tutorial - The First Law of Thermodynamics
We have finished the first of three lessons in our newest Chemistry Tutorial chapter on
Thermodynamics chapter is heating up. Our most recent page, titled
The First Law of Thermodynamics, explains what is meant by the law of energy conservation.
October 8, 2025
Chemistry Tutorial - Spontaneous Processes
Our newest Chemistry Tutorial chapter on
Thermodynamics chapter is heating up. Our second page, titled
Spontaneous Processes, is now live. Don't think about it; be spontaneous. Tap that link and read our description of spontaneity.
October 7, 2025
Chemistry Tutorial - Chapter 17 Table of Contents
The construction of our newest Chemistry Tutorial chapter on the topic of
Thermodynamics has begun. We have published our Table of Contents. (We are still on schedule to finish up by the end of the calendar year - December 31, 2025.)
Chemistry Tutorial - What is Thermodynamics?
The first page of our newest Chemistry Tutorial chapter on
Thermodynamics chapter is now live. The page, titled
What is Thermodynamics?, introduces the topic of Chemical Thermodynamics as the branch of science that helps us answer: Which chemical and physical changes are possible, in which direction do they proceed, and how far will they proceed?
October 6, 2025
Chemistry Tutorial - Titration Analysis
Our final page of
Chapter 16 of our
Chemistry Tutorial has been published. The page, titled
Titration Analysis, explains how a titration curve is more than just a shape—it’s a story of acid, base, and equilibrium. We break down how to compute the pH at key points (before, at, and after equivalence) in a weak-acid/strong-base titration.
With Chapter 16 complete, we should have plans and initial pages for Chapter 17 coming out within a few days. Chapter 17 is on the topic of Thermodynamics.
October 2, 2025
Chemistry Tutorial - Common Ion Effect and Buffers
Our newest page from
Chapter 16 of our
Chemistry Tutorial explains how the common ion effect shifts equilibrium and plays a central role in the function of buffers, allowing solutions to resist drastic pH changes. Visit
Common Ion Effect and Buffers and learn to use ICE tables and the equilibrium model to analyze such systems and predict their pH.
October 1, 2025
Chemistry Tutorial - Determining the pH of Salts
Determining the pH of salt solutions involves understanding hydrolysis, the relationship between K
a and K
b, and the use of an ICE table to relate equilibrium concentrations to an equilibrium constant value. This latest page of
Chapter 16 of our
Chemistry Tutorial, titled
Determining the pH of Salts, explains how to calculate the pH of a salt solution.
September, 2025
September 30, 2025
Chemistry Tutorial - Dissociation of Polyprotic Acids
From diprotic to triprotic acids, understanding the sequential dissociation process helps students master equilibrium concepts and acid strength comparisons. Our page on
Dissociation of Polyprotic Acids provides the details.
September 29, 2025
Curriculum Corner - Chemistry: Chapter 15, Acids and Bases
We have just uploaded eight new Think Sheets for our
Acids and Bases chapter of the Curriculum Corner. Think Sheets coordinate with our Tutorial pages on the same topic. They serve as useful in-class practice of chemistry concepts and mathematical relationships. Best of all: they can be downloaded for free. Think Sheets for
all Chemistry topics can be found on the main page of the Curriculum Corner section.
September 26, 2025
Study Cards for Solutions Chapter of Chemistry Tutorial
September 25, 2025
Study Cards for Solutions Chapter of Chemistry Tutorial
There has been a lot of fine tuning of our Chemistry Tutorial over the past several months, beginning with Chapter 1. We have improved our section headings, added ALT tags to all images, and tailored our meta-data for search engines. We have reached Chapter 13 and are now adding missing Study Cards. You will find new Study Cards for the following pages:
Solubility and Structure |
The Dissolving Process
Links to Study Cards are found in the Before You Leave section near the bottom of each page.
September 15, 2025
Chemistry Tutorial - Percent Dissociation and Ka
Our second of six pages in Lesson 2 of our
Solutions Equilibria chapter is now live. The page, titled
Percent Dissociation and Ka, helps students to solve Ka problems involving percent dissociation values.. This page explains how percent dissociation measures how much of a weak acid ionizes in solution, linking directly to Ka values. Understanding this relationship makes it easier to solve acid dissociation problems.
September 11, 2025
Chemistry Tutorial - Weak Acid and Base Dissociation
Our first of six pages in Lesson 2 of our
Solutions Equilibria chapter is now live. The page, titled
Weak Acid and Base Dissociation, explains how
using K
a and K
b, ICE tables, and some algebra, the pH and ion concentrations of aqueous solutions of weak acids and weak bases can be calculated. This page demonstrates the details of how to solve such problems with numerous examples and some practice problems with answers.
September 9, 2025
Chemistry Tutorial - The Common Ion Effect
We have just completed Lesson 1 of our
Solutions Equilibria chapter. The page, titled
The Common Ion Effect, explains how
solubility isn’t fixed. When an insoluble salt is dissolved in a solution that already contains one of its ions, the equilibrium system responds by reducing the solubility. Learn the concept and the mathematics in the usual organized presentation.
September 8, 2025
Chemistry Tutorial - Ksp and Solubility
Our second page of Lesson 1 of our
Solutions Equilibria chapter is now live. The page, titled
Ksp and Solubility, takes the guesswork out of solubility problems. The page illustrates through numerous examples and practice problems how ICE tables plus a K
sp equation provide a clear path to finding ion concentrations and molar solubility - even in the most difficult algebraic cases.
Replay Activity
Finished a Concept Builder, Minds On, Science Reasoning or Physics Interactive? Now you can Replay them for extra practice. Logged in users will see a replay button on the interactive's page, as well as a Replay button on their Task Listing if the activity is completed. For CalcPad you will need to either do the public version of an assignment, or have the teacher clone the assignment.
September 5, 2025
Chemistry Tutorial - The Solubility Product Constant
Our first page of Lesson 1 of our
Solutions Equilibria chapter is now live. The page, titled
The Solubility Product Constant, describes the dissolving of
insoluble salts in water, explains how it should be viewed as an equilibrium system, and discusses the solubility product constant.
Chemistry Tutorial - Ksp Reference Page
We added a new page to
the Reference section of our Chemistry Tutorial. It includes K
sp values for about 200 insoluble salts. They organized by anion.
September 3, 2025
Chemistry Simulation: VSEPR Molecules
We have uploaded a new Chemistry simulation to our Interactives collection. It is titled
VSEPR (Valence Shell Electron Pair Repulsion) and it shows the geometry of molecules as you add bonds and lone electron pairs. This helps you see why some molecules look and act the way they do.
Physics Simulation: Static Equilibrium
We have uploaded a new Physics simulation to our Interactives collection. It is titled
Static Equilibrium and features a force and torque analysis of a ladder leaning against a wall. Variables such as the ladder's length, mass, and angle and the coefficient of friction can be varied. A person of designated mass can be positioned on the ladder at any chosen location.
Physics Simulation: Magnetic Field Sim (Kirby)
We have uploaded a new Physics simulation to our Interactives collection. It is titled
Magnetic Field Sim (Kirby) and it allows you to see and modify the magnetic fields around a current carrying wire. Current, strength and other values can be adjusted.
Chemistry Tutorial - Chapter 16 Table of Contents
We have begun the planning of Chapter 16 of our Chemistry Tutorial. The chapter is titled
Solutions Equilibria and will include the equilibrium analysis of the dissolving of slightly soluble salts and the dissociation of weak acids and weak bases. The Chapter will be very mathematical and most fitting for honors and advanced Chemistry classwork. Our table of contents is available for viewing. The first page should be out tomorrow.
September 2, 2025
Chemistry Tutorial: Ka and Kb Values of Conjugate Acid-Base Pairs
We have just completed
Chapter 15 on Acids and Bases in our Chemistry Tutorial. Our newest page is titled
Ka and Kb Values of Conjugate Acid-Base Pairs.This lesson describes how conjugate acid–base pairs are connected through K
a and K
b values. It also explains how to use the values to determine if a salt is acidic, basic, or neutral (including salts that contain a conjugate base of a polyprotic acid).
We will begin Chapter 16 this week. The newest chapter is heavil