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Worked Chemistry Problems

Use these worked examples problems to help solve related problems in your own chemistry homework or to better grasp chemical concepts. These are general & introductory chemistry problems, with links to related resources.

Lewis Structure Example Problem
This example problem shows how to draw a Lewis dot structure of a molecule.

Index of Worked Chemistry Problems
This is a one-page index of all of the worked chemistry problems on the site, arranged alphabetically and also arranged according to the order in which they are (typically) presented in a general chemistry text.

Printable Chemistry Worksheets
This is a collection of chemistry worksheets in pdf format. The answers to the questions are available on separate worksheets so you can fill them out and then check your work.

Balancing Chemical Equations
Here is a step-by-step tutorial for balancing chemical equations, along with a worked example. This is a must-read for students of general and introductory chemistry!

Unit Conversion Worksheets
Use these printable worksheets to practice unit conversions. These pdf questions and answers will test your understanding of metric-metric, metric-English, and temperature conversions.

Concentration and Molarity
These are examples of concentration and molarity calculations, with links to other worked chemistry problems and homework help.

Balancing Redox Reactions
Get step-by-step instructions for balancing redox reactions for conservation of mass and charge in electrochemistry.

Avogadro's Number Example Chemistry Problem
Avogadro's number is the number of atoms or molecules in a mole. Here is an example of using this number to determine the mass of a single atom based on the atomic mass of that atom.

Avogadro's Number Example Chemistry Problem
Avogadro's number is the number of atoms or molecules in a mole. Here is an example of using this number to determine the mass of a known number of molecules.

Avogadro's Number Example Chemistry Problem
Avogadro's number is the number of atoms or molecules in a mole. Here is an example of using this number to determine the number of molecules contained in a known mass of molecules.

Atomic Mass from Atomic Abundance Example Chemistry Problem
Atomic mass is determined by the weighted average of the masses of naturally-occurring isotopes. Here is an example of how to determine the atomic mass from known atomic abundances.

Atomic Mass & Isotopic Abundance
These are examples of atomic mass and isotopic abundance calculations, with links to other worked chemistry problems and homework help.

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.

Avogadro's Number
These are examples of calculations involving Avogradro's number, with links to other worked chemistry problems and homework help.

Balance Redox Reaction Example Problem
When balancing redox reactions, the overall electronic charge must be balanced in addition to balancing the atoms of the reactants and products. This example problem illustrates how to use the half-reaction method to balance redox reactions.

Bohr Atom Energy Level Example Problem
This example problem demonstrates how to find the energy that corresponds to an energy level of a Bohr atom.

Balance Redox Reaction in Basic Solution Example Problem
Redox reactions commonly take place in acidic solutions, but these reactions also take place in basic solutions. This example problem shows how to balance a redox reaction in a basic solution.

Boiling Point Elevation Example Problem
This example problem demonstrates how to calculate boiling point elevation.

Bond Energies & Enthalpies
This is a step-by-step worked problem to help you calculate bond energies and enthalpies for gaseous reactions.

Avogadro's Law Calculation
Avogadro's Law is a specific instance of the Ideal Gas Law in which volume is directly proportional to the number of moles at constant temperature and pressure. Here's how to solve a direct proportion problem using Avogadro's Law.

Bond Energies and Enthalpy Change Example Chemistry Problem
Bond energies and enthalpy can be used to determine if a reaction is endothermic or exothermic. Here is an example showing how to determine the change in enthalpy of a reaction.

Boyle's Law
Here's an introduction to Boyle's Law, as well as a worked example problem and links to related resources.

Convert Wavelength to Frequency Worked Example Problem
This example problem demonstrates how to find the frequency of light from the wavelength.

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.

Aqueous Solution Dilution
Here is a worked example of how to calculate a dilution of a stock solution.

Enthalpy Change Example Problem
Worked Example Chemistry Problems - Determining change in enthalpy of a reaction using Hess's Laws.

Calorimetry and Heat Flow
There's a worked example for coffee cup calorimetry and another for bomb calorimetry, with links to review calorimetry and thermochemistry concepts.

Chemistry Problems
The best way to learn chemistry is to practice working problems, but it helps to see how each type of problem is solved. Follow examples of worked chemistry problems. These chemistry problems are arranged alphabetically according to subject. Multiple worked examples are given for several types of problems.

Enthalpy Change Example Problem
Worked Example Chemistry Problems - Determining change in enthalpy of melting ice and vaporizing water. Additional worked problem to determine mass of ice melted from given energy value.

Enthalpy Change Example Problem
Worked Example Chemistry Problems - Determining change in enthalpy of a reaction using Hess's Laws.

Concentration and Molarity Worked Example Problem
This is a worked example showing the steps necessary to find the concentration of a solution when given the amount of solute.

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.

Concentration and Molarity Worked Example Problem
This is a worked example showing the steps necessary to create a stock solution of predetermined concentration.

Empirical Formula
Learn how to find the empirical formula from percent composition data.

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.

Gram to Mole Conversions
Here are worked examples problems for mole to gram or gram to mole conversions.

Equilibrium Constant Example Problem
This example problem demonstrates how to use the equilibrium constant of a reaction to determine equilibrium concentrations of reactants and products.

Equilibrium Constant Example Problem
This example problem demonstrates how to find the equilibrium constant of a reaction from equilibrium concentrations of reactants and products.

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.

Ideal Gas Law
Here are some worked examples of Ideal Gas Law chemistry problems plus links to formulas for working gas problems and related chemistry tools and resources.

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.

Heats of Formation
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.

How to Calculate Molarity of a Solution
Molarity is a unit of concentration measuring the number of moles of a solute per liter of solution. The strategy to solving molarity problems is fairly simple. This outlines a straightforward method to calculate molarity of a solution.

How to Calculate the Limiting Reactant of a Chemical Reaction
Chemical reactions rarely occur when exactly the right amount of reactants will react together to form products. One reactant will be used up before another runs out. This reactant is known as the limiting reactant. This is a strategy to follow when determining which reactant is the limiting reactant.

Ideal Gas Example Problem - Constant Pressure
Here is an example of an ideal gas problem where the pressure of the gas is held constant.

Isotopes and Nuclear Symbols
These are examples of isotope and nuclear symbol problems, with links to other worked chemistry problems and homework help.

Joule to Electron Volt Conversion Example Problem
This example problem demonstrates how to convert joules to electron volts.

Mass Percent Composition Problem #2
This is worked example problem showing how to calculate mass percent composition.

Henderson Hasselbalch Equation and Example
You can calculate the pH of a buffer solution or the concentration of the acid and base using the Henderson Hasselbalch equation. Here's a look at the Henderson Hasselbalch equation and a worked example that explains how to apply the equation.

Law of Multiple Proportions
Here's an example of a Law of Multiple Proportion problem, with links to other worked chemistry problems and homework help.

Limiting Reactant and Theoretical Yield
These are examples of calculations for determining the limiting reactant and theoretical yield of a reaction, with links to other worked chemistry problems and homework help.

Mean or Average - Calculate the Mean
It's very important to know how to calculate the mean or average of a set of numbers. Among other things, this will allow you to calculate your grade point average. However, you'll need to calculate the mean for several other situations, too.

Mass Percent Composition
These are examples of mass percent composition calculations, with links to other worked chemistry problems and homework help.

Molality Example Problem
Here is an example of calculating concentration or molality of a solution.

Mass Relations in Balanced Equations
These are examples of calculations for determining the mass relations in balanced chemical equations, with links to other worked chemistry problems and homework help.

Mole - Gram Conversions
These are examples of mole-to-gram and gram-to-mole conversions, with links to other worked chemistry problems and homework help.

Molecular Formula from Simplest Formula
These are examples of calculations for determining the molecular formula from the simplest formula and approximate molecular mass, with links to other worked chemistry problems and homework help.

Molecular Mass Calculations
These are examples of molecular mass calculations, with links to other worked chemistry problems and homework help.

Osmotic Pressure Example
This example problem demonstrates how to calculate the osmotic pressure of a solution.

Oxoacid Example Chemistry Problem
This chemistry example problem explains how to identify the strongest acid from a list of oxoacids.

Population Standard Deviation Example Calculation
This is a simple example of how to calculate population standard deviation.

Molarity Example Problem
Here is an example of calculating concentration or molarity of a solution.

Predicting Formulas of Compounds with Polyatomic Ions
This is a tutorial for problems determining the formulas of compounds containing polyatomic ions. Links are included to the periodic table, a chart of common polyatomic ions, group chemistry, and valences of the elements.

Predicting Formulas of Ionic Compounds
This is a tutorial for working through problems asking you to determine the formulas of ionic compounds. Links are included to the periodic table, group chemistry, and valences of the elements.

Protons & Electrons in Ions
These are examples of calculations used to determine the number of protons and electrons in ions, with links to other worked chemistry problems and homework help.

Molecular Mass from Molecular Formula
Use these worked example chemistry problems to help practice calculating molecular mass from the molecular formula.

Pressure Conversions
Here are some examples of conversions between units of pressure (kPa, atm, mm Hg).

Theoretical Yield Worked Problem
This example problem demonstrates how to calculate the amount of reactant needed to produce a product.

Percent Composition by Mass
Here is an example of calculating concentration using percent composition by mass of a solution.

Uncertainty Sample Calculation
This is a worked example problem that shows how to determine uncertainty in measurements. Uncertainty is related to precision and significant figures.

Molecular Formula and Simplest Formula Example Problem
This is a worked example of how to determine the molecular formula of a substance when given the simplest formula and the mass from experimental data.

Predicting Formulas of Compounds with Polyatomic Ions Example Problem
This example problem demonstrates how to predict the molecular formulas of several compounds involving polyatomic ions.

Predicting Formulas of Ionic Compounds Example Problem
This worked example problem demonstrates how to predict the molecular formulas of ionic compounds.

Reactions in Aqueous Solution
These are examples of calculations for determining limiting reactant, theoretical yield, number of moles, and mass in grams for reactions in water solutions.

de Broglie Example Problem
This example problem demonstrates how to find the wavelength of a moving electron using de Broglie's equation.

Sample Standard Deviation Example Calculation
This is a simple example of how to calculate sample standard deviation.

Energy from Wavelength Example Problem
This example problem demonstrates how to find the energy of a photon from its wavelength.

Molarity of Ions Example Problem
This example problem demonstrates how to calculate the molarity of ions in an aqueous solution.

Simplest Formula from Percent Composition
These are examples of calculations for determining the simplest formula of a compound from its percent composition, with links to other worked chemistry problems and homework help.

Calculate Root Mean Square Velocity of Gas Particles
This example problem demonstrates how to calculate the root mean square velocity of particles in an ideal gas.

Ideal Gas vs Non-ideal Gas Example Problem
This example problem demonstrates how to calculate the pressure of a gas system using the ideal gas law and the van der Waal's equation. It also demonstrates the difference between an ideal gas and a non-ideal gas.

Electronegativity and Bond Polarity Example Problem
This example problem demonstrates how to use electronegativity to determine bond polarity and whether or not a bond is more covalent or more ionic.

Clausius–Clapeyron Equation Example Problem
This example problem demonstrates how to use the Clausius–Clapeyron equation to predict the vapor pressure of a solution.

Temperature Conversions
These are examples of temperature conversion problems, with links to other worked chemistry problems and homework help.

Rates of Reaction Example Problem
This example problem demonstrates how to use reaction rates to determine the coefficients of a balanced chemical equation.

Activation Energy Example Problem
This example problem demonstrates how to determine the activation energy of a reaction from reaction rate constants at different temperatures.

Unit Conversions
These are examples of unit conversion problems, with links to other worked chemistry problems and homework help.

Theoretical Yield Example Problem
This example problem demonstrates how to predict the amount of product produced from a given amount of reactants.

Limiting Reactant Example Problem
To predict the yield of a chemical reaction, it is important to be able to identify the limiting reactant. This example problem demonstrates a method to determine the limiting reactant of a chemical reaction.

How to Predict Precipitates
When two aqueous solutions of ionic compounds are mixed together, the resulting reaction may produce a solid precipitate. This guide will illustrate how to use the general solubility rules to predict whether or not the product will remain in solution or form a precipitate.

Raoult's Law Example Problem
This example problem demonstrates how to use Raoult's Law to calculate the change in vapor pressure by adding a strong electrolyte to a solvent.

Convert Frequency to Wavelength Worked Example Problem
This example problem demonstrates how to find the wavelength of light from the frequency.

Energy from Frequency Example Problem
This example problem demonstrates how to find the energy of a photon from its frequency.

Galvanic Cell Example Problem
Galvanic cells are electrochemical cells which use the transfer of electrons in redox reactions to supply an electric current. This example problem illustrates how to form a galvanic cell from two reduction reactions and calculate the cell EMF.

Freezing Point Depression Example Problem
This example problem demonstrates how to calculate freezing point depression.

Raoult's Law Example Problem
This example problem demonstrates how to use Raoult's Law to calculate the of vapor pressure of two volatile solutions mixed together.

Cell Potential and Free Energy Example Problem
The Gibbs free energy of the reactions occurring an electrochemical cell can be related to the total cell potential. This example problem shows how to calculate the maximum theoretical free energy and determine if the reaction is spontaneous from the total cell potential.

Nernst Equation Example Problem
The Nernst equation is used to calculate cell potentials in non-standard conditions. The Nernst equation modifies the standard cell potential to account for temperature and concentrations of the reaction participants. This example problem uses the Nernst equation to calculate a cell potential.

Equilibrium Constant of an Electrochemical Cell Reaction Example Problem
The equilibrium constant of an electrochemical cell's redox reaction can be determined using the Nernst equation. This example problem shows how to use reaction conditions at equilibrium and the Nernst equation to calculate the equilibrium constant of a cell's redox reaction.

Henry's Law Example Problem
This example problem demonstrates how to use Henry's Law to calculate the concentration of a gas in solution under pressure.

Electron Volt to Joule Conversion Example Problem
This example problem demonstrates how to convert electron volts to joules.

Osmotic Pressure Example
This example problem demonstrates how to calculate the amount of solute to add to create a specific osmotic pressure in a solution.

Raoult's Law Example Problem
This example problem demonstrates how to use Raoult's Law to calculate the change in vapor pressure by adding a nonvolatile liquid to a solvent.

Convert Molarity to Parts Per Million Example Problem
This example problem demonstrates how to convert molarity to parts per million.

Mean, Median, Mode and Range
This worked example problem shows how to calculate the mean, median, mode and range of a series of numbers.

Solubility Product From Solubility Example Problem
This example problem demonstrates how to determine the solubility product of an ionic solid in water from a substance's solubility.

How to Calculate Theoretical Yield of a Chemical Reaction
Before performing chemical reactions, it is helpful to know how much product will be produced with given quantities of reactants. This is known as the theoretical yield. This strategy makes calculating theoretical yield a simple process.

Solubility From Solubility Product Example Problem
This example problem demonstrates how to determine the solubility of an ionic solid in water from a substance's solubility product.

How to Calculate Mass Percent
Mass percent composition of a molecule shows the amount each element in a molecule contributes to the total molecular mass. Each element's contribution is expressed as a percentage of the whole. This tutorial will show the method to determine the mass percent composition of a molecule.

Beta Decay Nuclear Reaction Example Problem
This example problem demonstrates how to write a nuclear reaction process involving beta decay.

Beta-+ Decay Nuclear Reaction Example Problem
This example problem demonstrates how to write a nuclear reaction process involving beta-+ decay.

How to Calculate the Empirical and Molecular Formula of a Compound
The empirical formula of a chemical compound is a representation of the simplest whole number ratio between the elements comprising the compound. The molecular formula is the actual whole number ratio between the elements of the compound. This tutorial shows how to determine the empirical and molecular formulas for a compound from mass percent...

How to Draw a Lewis Structure
Lewis dot structures are useful to predict the geometry of a molecule. This example problem shows the steps needed to draw a structure where one atom violates the octet rule.

Formal Charge Example Problem
Formal charge is a technique to identify which resonance structure is the more correct structure. The most correct Lewis structure will be the structure where the formal charges are evenly distributed throughout the molecule.

Oxidation State Example
The oxidation state of an atom in a molecule refers to the degree of oxidation of that atom. This example problem shows how to assign oxidation states to a variety of atoms in molecules.

Relative Solubility Example Problem
This example problem demonstrates how to determine the relative solubility of ionic compounds in water.

Oxidation and Reduction Reaction Example Problem
It is often confusing to identify which molecule is oxidized in the reaction and which molecule is reduced in a redox reaction. This example problem shows how to correctly identify which atoms undergo oxidation or reduction and their corresponding redox agents.

Electrochemical Cell EMF Example Problem
The electromotive force, or EMF of a electrochemical cell is the net voltage of the oxidation and reduction half-reactions in a redox reaction. This example problem shows how to calculate the cell EMF using standard reduction potentials of reduction half-reactions.

Equilibrium Concentration Example Problem
This example problem demonstrates how to calculate the equilibrium concentrations from initial conditions and the reaction's equilibrium constant. This equilibrium constant example concerns a reaction with a "large" equilibrium constant.

Equilibrium Constant For Gaseous Reactions Example Problem
This example problem demonstrates how to find the equilibrium constant and pressure equilibrium constant of a gaseous reaction from the pressures of the gases.

What Is Oxidized And What Is Reduced in Oxidation and Reduction Reactions?
In oxidation-reduction or redox reactions, it is important to be able to identify which atoms are being oxidized and which atoms are being reduced. To identify if an atom is either oxidized or reduced, you only have to follow the electrons in the reaction.

Working with Density
This example problem shows how to calculate the mass of an object from a known density and volume.

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.

Equilibrium Constant and Reaction Quotient Example Problem
This example problem demonstrates how to use the reaction quotient to predict the direction of a chemical reaction towards equilibrium.

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