Thermodynamics & Thermochemistry
Laws of Thermochemistry
Certain rules or laws apply to thermochemical equations and enthalpy. These are explanations and examples of these laws, including Hess's Law.
Standard State Conditions
Values of thermodynamic quantities are commonly expressed for standard state conditions, so it is a good idea to understand what the standard state conditions are.
Endothermic and Exothermic Reactions
Learn about endothermic and exothermic chemical reactions and get instructions to perform your own hot and cold chemistry demonstrations.
Endothermic Reaction Examples
Are you looking for examples of endothermic reactions for homework or to set up a demonstration? Here's a list of several heat-absorbing or endothermic chemical reactions and processes.
What Is Absolute Zero?
Learn about absolute zero and the Kelvin and Celsius temperature scales.
Heats of Formation - Anions & Cations
This is a table of molar heats of formation for common anions and cations in aqueous solution.
Heats of Formation of Compounds
This is a table of the heats of formation for a variety of common compounds.
Heats of Formation Calculation
These are examples of how to calculate the heats of formation for compounds and ions in aqueous solution. Links are given to rules of thermochemistry and explanations of endothermic and exothermic reactions.
Single Bond Energies
This is a table of single bond energies in units of kJ/mol at 25°C. Use these values to predict whether a reaction will be endothermic or exothermic and to calculate change in enthalpy for gases.
Bond Energies & Enthalpies
This is a step-by-step worked problem to help you calculate bond energies and enthalpies for gaseous reactions.
Calorimetry - Coffee Cup Calorimetry and Bomb Calorimetry
A calorimeter is a device used to measure the quantity of heat flow in a chemical reaction. Two of the most common types of calorimeters are the coffee cup calorimeter and the bomb calorimeter.
Calorimetry and Heat Flow - Sample Calculation
There's a worked example for coffee cup calorimetry and another for bomb calorimetry, with links to review calorimetry and thermochemistry concepts.
This is a set of worked thermochemistry problems for calculating the change in enthalpy. Links are given to rules of thermochemistry and explanations of endothermic and exothermic reactions.
Clausius–Clapeyron Equation Example Problem
This example problem demonstrates how to use the Clausius–Clapeyron equation to predict the vapor pressure of a solution.
Entropy Example Problem
This example problem demonstrates how to calculate the change in entropy of a system's surroundings following a chemical reaction at constant temperature and pressure.
Entropy and Reaction Spontaneity Example Problem
This example problem demonstrates how to use changes in entropy of a system and its surroundings to determine a reaction's spontaneity and whether or not the reaction will be exothermic or endothermic.
Free Energy and Reaction Spontaneity Example Problem
This example problem demonstrates how to calculate and use changes in free energy to determine a reaction's spontaneity.
Entropy Change Example Problem
This example problem demonstrates how to examine the reactants and products to predict the sign of the change in entropy of a reaction. Knowing if the change in entropy should be positive or negative is a useful tool to check your work on problems involving changes in entropy. It is easy to lose a sign during thermochemistry homework problems.
Hess's Law Example Problem
This example problem demonstrates strategies and how to use Hess's Law to find the enthalpy change of a reaction using enthapy data from similar reactions.
Free Energy and Pressure Example Problems
This example problem demonstrates how to determine free energy of a reaction at conditions that are not standard states.
Entropy of Reaction Example Problem
This example problem demonstrates how to find the entropy of reaction from standard molar entropy data on the reactants and products.
Name 5 Types of Energy
Energy comes in various forms. Here are 5 main types of energy and examples of them.
What Are 2 Forms of Energy?
Scientists classify energy into 2 main types or forms. Here is a look at the forms of energy, with examples of each type.