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.
October, 2025
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 heavily mathematical and more oriented towards honors and advance students of Chemistry. It is titled Solutions Equilibria.
August, 2025
August 28, 2025
Chemistry Tutorial: Hydrolysis of Salts
We have started our 5th and final lesson of
Chapter 15 on Acids and Bases in our Chemistry Tutorial. Our newest page discusses
Hydrolysis of Salts. The page describes how dissolved salts don’t always form neutral solutions. Some form acidic or basic solutions through hydrolysis. This lesson explains the principles and rationale and uses clear examples to help students master the hydrolysis of salts and draw conclusions about the acidity/basicity of salt solutions.
August 26, 2025
Chemistry Tutorial: Titration in the Chemistry Lab
We have completed Lesson 4 of
Chapter 15 on Acids and Bases in our Chemistry Tutorial. Our newest page discusses
Titration in the Chemistry Lab. The page describes the analytical nature of titration, the logic behind the selection of an indicator, and the stoichiometry considerations that allow one to determine the unknown molarity. There are several example problems, a Check Your Understanding section, and links to further practice problems.
August 22, 2025
Chemistry Tutorial: Acid-Base Neutralizations with a Weak Acid or Base
Our second page of Lesson 4 of
Chapter 15 on Acids and Bases in our Chemistry Tutorial is now published. Our newest page discusses
Acid-Base Neutralizations with a Weak Acid or Base. The page explains the phenomenon of strong acid/weak base, weak acid/strong base, and weak acid/weak base neutralization reactions. Equation writing, particle diagrams, pH curves, and a little stoichiometry saturate the page.
August 21, 2025
Chemistry Tutorial: Acid-Base Neutralization
We have started Lesson 4 of
Chapter 15 on Acids and Bases in our Chemistry Tutorial. Our newest page, titled
Acid-Base Neutralization,
explores what acid-base neutralization reactions are, how to write molecular and net ionic equations, and how to perform neutralization stoichiometry using moles and using volumes and molarities.
August 20, 2025
Chemistry Tutorial: Reference Section - Dissociation Constants
Our Chemistry Tutorial has a Reference Section with a growinig collection of data, tables, and other useful resources. We have just added a page to this section that is titled
Dissociation Constants. The page lists K
a and K
b values for a large collection of acids and bases. Data is ordered alphabetically by substance name and organized by type - e.g., weak acids, weak bases, polyprotic acids. It's a mother-lode of data, all organized in one place.
August 19, 2025
Chemistry Tutorial: Dissociation Constants
We have completed Lesson 3 of
Chapter 15 on Acids and Bases in our Chemistry Tutorial. Our newest page, titled
Dissociation Constants,
explores how K
a and K
b values relate to acid-base strength, hydronium ion concentration, and pH, using diagrams, tables, and calculations. One more Lesson to go in Chapter 15.
August 14, 2025
Chemistry Tutorial: Strong And Weak Acids and Bases
August 13, 2025
Chemistry Tutorial: pH Indicators
August 6, 2025
Chemistry Tutorial: Chapter 15 on Acids and Bases
Our fourth Tutorial page in
Chapter 15 has been published. The page, titled
The pH Scale, covers the conceptual and mathematical nature of pH. The page explores the meaning of pH and how it relates to acidity and basicity and shows how to calculate pH, pOH, [H₃O⁺], and [OH⁻]. Numerous examples, practice opportunities (with answers), and suggestions for further learning are provided.
August 4, 2025
Chemistry Tutorial
We have optimized (we hope), improved (we hope), and uploaded (we're certain of it) updates on Chapter 4 (
Compounds, Formulas, and Names) and Chapter 5 (
Modern Atomic Model). Most improvements have been directed towards improving accessibility and optimizing the chances of the pages showing up higher on Google searches. As such, many changes will be transparent to most people.
August 1, 2025
Chemistry Tutorial: Chapter 15 on Acids and Bases
Our third Tutorial page in
Chapter 15 is now live. The
new page details
water's self-ionization is now live. Learn how water undergoes self-ionization to produce hydronium and hydroxide ions. Understand the ion product constant (Kw) and how ion concentrations determine if a solution is acidic, basic, or neutral.
July, 2025
July 31, 2025
Chemistry Tutorial: Chapter 15 on Acids and Bases
We have published our second page of Chapter 15 of our Chemistry Tutorial. This will be a critical page discussing models of acids and bases, and giving copious attention to the Bronsted-Lowry acid-base model. The page includes numerous chemical equations and particle diagrams showing proton transfer and the resulting conjugate acid-base pairs. The page includes numerous opportunities to practice and suggestions for furthering student understanding.
July 29, 2025
Chemistry Tutorial: Chapter 15 on Acids and Bases
Way ahead of schedule, we have started work on Chapter 15 of our Chemistry Tutorial. The table of contents is laid out and our first page on the
Properties of Acids abd Bases is complete.
Task Tracker: New Course Registration Options
When creating or editing your courses, you can now select from 4 different Student Registration Options. Disabled (only those the teacher Adds through Course -> Add Students), Anyone (anyone can sign up with the course sign up code), Subscribers (Only those added by the teacher or added by the Task Tracker Subscription manager), and Valid Domains (anyone can register as long as they have the course code AND their email address matches your organization's email domain - Goodbye mistyped student emails or students signing up with personal email addresses).
July 28, 2025
Chemistry Tutorial: Chapter 3 - CYUs and Study Cards
July 25, 2025
Chemistry Tutorial: Chapter 2 - CYUs and Study Cards
We have made sure all pages of Chapter 2 have Check You Understanding sections; a few pages were missing some. And we have also added the