Some of the virtual chemistry experiments and exercises employ applets representing chemical equipment. These applets are available for use in creating new web pages.
Browsers must support Java 1.1 or higher in order to execute the applets employed in these pages. JavaScript support is also required. These pages and applets have been tested and found to run correctly under Netscape Navigator 4.73 and Internet Explorer 5.
Some pages employ VRML (Virtual Reality Modeling Language) to display "three-dimensional" images of molecular structure and orbitals. A VRML viewer such as SGI Cosmo Player is required. These pages have been tested and found to display correctly under Netscape Communicator 4.73 with CosmoPlayer 2.1.1. Some pages function correctly under Internet Explorer 5.0 while other pages cause Internet Explorer 5.0 to crash.
Some of the VRML files are relatively large (several hundred KB) and may take a few minutes to download if your internet connection is slow.
Feedback on the performance of these pages with other browsers would be appreciated. EAI is required for modifications of the VRML image. If a browser does not support EAI, the VRML image may still appear, but the buttons will not be functional and use of the buttons may cause the browser to crash.
Physlets (Physics Applets) are small flexible Java applets designed for science education. Data Connections is a component of Physlets that permits inter-applet exchange of data and is used in many of the chemistry applets listed below. For more information on Physlets and to obtain the archives and documentation, visit the Physlet home page. A good introduction to Physlets technology is the Physlets book by Wolfgang Christian and Mario Belloni.
Atomic Structure
Chemical AnalysisChemical Bonding
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Chemical EquilibriaChemical KineticsCrystal Structure
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GasesPhase ChangesThermodynamics |
| Topic | Concepts | Experiment |
|---|---|---|
| Atomic Orbitals | Isosurfaces of various atomic orbitals and some hybrid orbitals are displayed. | |
| Orbitals | Isosurfaces, radial distribution plots, and electron density plots of various atomic orbitals are displayed. | |
| Graphical Representations of Orbitals | The quantum numbers for hydrogen orbitals are explained. Three ways of representing orbitals (radial distribution, electron density, and isosurface plots) are described. | A radial distribution plot, an electron density plot, and a virtual reality isosurface plot for the hydrogen 1s orbital are displayed to illustrate the significance and use of each type of orbital representation. |
| s Orbitals | The quantum numbers for s orbitals are identified. | The shape of s orbitals is explored. For s orbitals with various principal quantum numbers, radial distribution, electron density, and isosurface plots are examined to determine the number and shapes of nodal surfaces and the region where the electron is most likely to be found. |
| p Orbitals | The quantum numbers for p orbitals are identified. | The shape and orientations of p orbitals are explored. For p orbitals with various principal quantum numbers, radial distribution, electron density, and isosurface plots are examined to determine the number and shapes of nodal surfaces. |
| d Orbitals | The quantum numbers for d orbitals are identified. | The shape and orientations of d orbitals are explored. For d orbitals with various principal quantum numbers, radial distribution, electron density, and isosurface plots are examined to determine the number and shapes of nodal surfaces. |
| Sizes of Atomic Orbitals | The shell designations for atomic orbitals are presented. | A virtual reality isosurface display is used to compare sets of atomic orbitals with various quantum numbers. This display allows direct comparison of the sizes of the orbitals. |
| Effective Nuclear Charge | The effect of shielding and the concept of an effective nuclear charge are explained. | A virtual reality isosurface display is used to compare the sizes of hydrogen 1s and 2s orbitals with various effective nuclear charges with the sizes of fluorine 1s and 2s orbitals. |
| Effective Nuclear Charge and Orbital Size | Slater rules for predicting shielding factors and Zeff are introduced. | A virtual reality isosurface display is used to compare the sizes of a hydrogen s orbital with a user-defined Zeff and an s orbital of a multi-electron atom. The best Zeff for the s orbital of the multi-electron atom is determined by matching the sizes of the orbitals and this value is compared with that predicted by the Slater rules. |
| Topic | Concepts | Experiment |
|---|---|---|
| Heat Capacity | Heat capacity and calorimetry are defined and explained. The use of calorimetry to measure heat capacity is described. | The heat capacity of an entire calorimeter system is determined. |
| Heat Capacity of a Calorimeter | Specific heat capacity is defined and explained. The calorimeter system is divided into components, in this example the calorimeter itself and the water in the calorimeter. A heat balance equation is written for the calorimeter system. | The heat capacity of the calorimeter is determined. |
| Specific Heat Capacity of Ethanol | The heat balance equation is written for a calorimeter containing ethanol. A graphical strategy is described for analyzing calorimetric data to simultaneously determine both the heat capacity of the calorimeter and the specific heat capacity of ethanol. | The heat capacity of the calorimeter and the specific heat capacity of ethanol are determined. |
| Specific Heat Capacity of Copper | In this calorimetry experiment, the components do not all have the same initial temperature. The mathematical handling of this situation is explained. | In the first experiment, the heat capacity of the calorimeter is determined using a metal (iron) with a known specific heat capacity. In the second experiment, the specific heat capacity of copper is determined. |
| Heat of Solution of Ammonium Nitrate | In this experiment, a chemical reaction serves as a source of heat in the heat balance equation. The molar enthalpy of reaction is defined and explained. | The molar heat of solution of ammonium nitrate is determined. |
| Heat of Neutralization | The neutralization reaction is explained. There are two reactants in the neutralization reaction; thus the limiting reactant must be identified in order to determine the molar enthalpy of neutralization. | The molar enthalpy of neutralization is determined. |
| Heat of Combustion of Methane | The combustion reaction for methane is explained and used to calculated the standard molar enthalpy of formation of methane. | The molar enthalpy of methane is determined and used to determine the standard molar enthalpy of formation of methane. The amount of methane that undergoes combustion is determined using the pressure of methan and the ideal gas law. |
| Heat of Solution of Sulfuric Acid | The nonideal loss and gain of heat during a calorimetry experiment is discussed. A graphical strategy for experimentally compensating for heat loss or gain is explained. | The heating or cooling rates of the calorimeter before and after an experiment are determined graphically. The molar enthalpy of solution of sulfuric acid is determined. |
| Heat of Solution of Calcium Hydroxide | Strategies are discussed for studying systems in which two chemical reactions occur simultaneously. | The molar enthalpy of solution of calcium hydroxide is determined. Nonideal heat loss/gain is modeled graphically. |
| Topic | Concepts | Experiment |
|---|---|---|
| Basic Concepts | The equilibrium state is describe in terms of the rate of the forward and reverse reactions for the reaction. The equilibrium constant (KP and KC) and the Law of Mass Action are introduced. | A stopped-flow apparatus is used to initiate and follow the progress of a reaction using concentration-time curves. |
| Equilibrium Constant | The equilibrium constant and its significance are discussed. | The equilibrium constants for two reactions with a single gas-phase product are measured. |
| Reaction Table | The use of a reaction table to manage stoichiometric calculations is described. | The equilibrium constants for two reactions are measured. |
| Le Chatelier's Principle: Adding and Removing Reactants and/or Products | Le Chatelier's Principle is introduced in the context of adding or removing reactants and/or products. The distinction between analytical amounts and equilibrium amounts of material is discussed. | The equilibrium amounts of carbon, water, carbon monoxide, and hydrogen for the steam reforming reaction are measured as the analytical amounts of the various species are changed. |
| Le Chatelier's Principle: Temperature Changes | Le Chatelier's Principle is used to predict the effect of a change in temperature on the composition of a system at equilibrium. | The equilibrium amounts of carbon, water, carbon monoxide, and hydrogen for the steam reforming reaction are measured as the temperature of the system is changed. |
| Le Chatelier's Principle: Volume Changes | Le Chatelier's Principle is used to predict the effect of a change in volume on the composition of a system at equilibrium. | The equilibrium amounts of carbon, water, carbon monoxide, and hydrogen for the steam reforming reaction are measured as the volume of the system is changed. |
| Topic | Concepts | Experiment |
|---|---|---|
| Reaction Rates | The stopped-flow technique and its use in studying chemical reactions is described. The speed or rate of a reaction is discussed. | Concentration vs time plots are recorded for reactants and product in a chemical reaction. Characteristic features for rates of change in the concentrations of reactants and product are explored. |
| Rate of Reaction | The relationships between the relative rates of change in concentration of reactants and products is discussed. The general expression for the rate of reaction is presented. | The stoichiometric coefficients for a chemical equation are determined by comparing the slopes of concentration-time plots for the reactants and products. |
| Differential Rate Laws | Differential rate laws for zero-, first-, and second-order reactions are described and explained. | The differential rate law and the rate constant are determined for a reaction by examining how the rate of reaction varies with the reactant concentration. |
| Integrated Rate Laws | Integrated rate laws for zero-, first-, and second-order reactions are described and explained. | The rate law and the rate constant are determined for a reaction by preparing characteristic kinetics plots from concentration-time data. |
| Half-life | The half-life of a reaction is defined and explained. | The half-life is measured for various initial concentrations for zero-, first-, and second-order reactions. The data is analyzed graphically to determine the relationship between the half-life and reactant concentration for each order reaction and to determine the rate constant for each reaction. |
| Method of Initial Rates | The determination of a rate law by the Method of Initial Rates is described. | The rate law and rate constant for a reaction is determined using the Method of Initial Rates. |
| Isolation Method | The determination of a rate law by the Isolation Method is described. | The rate law and rate constant for a reaction is determined using the Isolation Method. |
| Kinetics of the Bromate-Bromide Ion Reaction | The reaction between bromate ion and bromide ion in acidic aqueous solution is described. | The rate law and rate constant for the bromate-bromide ion reaction is determined. A selection of solutions and a stopped-flow apparatus are available. Students must devise their own experimental strategy for determining the rate law and the rate constant. |
| Topic | Concepts | Experiment |
|---|---|---|
| Closest-Packed Structures | The efficient packing of hard spheres is described. A sequence of interactive images are employed to illustrate the packing process for hexagonal closest-packed and cubic closest-packed structures. | |
| Cubic Closest-Packed Structure | The properties and unit cell of the cubic closest-packed structure are described. | An animation is provided and the viewer is asked to determine the number of atoms within the face-centered cubic unit cell. |
| Hexagonal Closest-Packed Structure | The properties and unit cell of the hexagonal closest-packed structure are described. | An animation is provided and the viewer is asked to determine the number of atoms within the hexagonal unit cell. |
| Topic | Concepts | Experiment |
|---|---|---|
| Pressure | The physical meaning of pressure and the operation of a U-tube manometer are explained. | Three exercises are provided: reading a manometer, measuring pressure when the manometer contains a liquid other than water, compensating for the vapor pressure of a volatile liquid in the manometer. |
| Boyle's Law | Boyle's experiments involving pressure and volume are discussed. | Students repeat Boyle's historical experiments and use the experimental data to formulate the relationship between the pressure and volume of a gas. |
| Boyle's Law Calculations | The use of Boyle's law to predict how the volume of a gas will change with a change in pressure is explained. | A sample of gas is allowed to expand. Students are asked to predict the change in pressure for the gas, and this prediction is tested. |
| Charles's Law | Charles's and Gay-Lussac's experiments involving temperature and volume are discussed. The significance of absolute zero is also discussed. | Students repeat Charles's historical experiments and use the experimental data to formulate the relationship between the temperature and volume of a gas and to determine absolute zero. |
| Avogadro's Law | Various characterizations of a gas are defined, including density, molar concentration, and molar volume. | The density, molar concentration, and molar volume of various gases are measured. |
| Ideal Gas Law and the Gas Constant | The various gas laws (e.g., Boyle's and Charles's laws) are employed to formulate a general gas law, the ideal gas law. | The validity of the ideal gas law is tested by measuring the pressure of a gas at various molar concentrations. The value of the gas constant is determined graphically. |
| Dalton's Law | The application of the ideal gas law to gas mixtures is explained, and the partial pressure of a gas is defined. | Two gases are allowed to mix, and students are asked to predict the final pressure of the gas mixture. |
| Topic | Concepts | Experiment |
|---|---|---|
| Atomic Orbitals | Isosurfaces of various atomic orbitals and some hybrid orbitals are displayed. | |
| Hybrid Orbitals | The origin and significance of hybrid orbitals is explained and illustrated with electron density plots and energy diagrams. | |
| Geometry of Hybrid Orbitals | The purpose of hybrid orbitals is explained. | Small balls are arranged in a linear, trigonal planar, or tetrahedral geometry. Various hybrid orbitals may be displayed and oriented towards the balls. Only the proper hybridization scheme will provide a set of orbitals that can simultaneously be directed at all of the balls. |
| Topic | Concepts | Experiment |
|---|---|---|
| Basic Concepts | The postulates of the kinetic molecular theory of gases are presented and discussed. | A molecular-dynamics simulation of a gas is presented. |
| Maxwell Distribution | The meaning of the Maxwell distribution is discussed. | A molecular-dynamics simulation of a gas is employed to explore the effect of temperature on the shape of the Maxwell distribution. |
| Pressure of a Gas | The physical origin of the pressure of a gas is discussed. | A molecular-dynamics simulation of a gas is employed to explore the effect of particle mass and number of particles (in a fixed volume) on the pressure of a gas. |
| Pressure-Volume Relation | A molecular-dynamics simulation of a gas is employed to explore the effect of system volume on the pressure of a gas under isothermal conditions. | |
| Pressure-Temperature Relation | A molecular-dynamics simulation of a gas is employed to explore the effect of system temperature on the pressure of a gas under isochoric conditions. | |
| Diffusion | A molecular-dynamics simulation of a gas is employed to explore the random-walk motion of a molecule. |
| Topic | Concepts | Experiment |
|---|---|---|
| Overlap of Atomic Orbitals: Sigma Bonding | The significance of orbital overlap in forming a chemical bond is explained. Sigma, pi, and delta bonding interactions are explained. | The overlap of two s orbitals is illustrated. |
| Overlap of Atomic Orbitals: Symmetry Requirements | The role of wave function sign and orbital symmetry in the overlap of atomic orbitals is discussed. | The overlap of an s and py orbital along the z axis is illustrated. |
| Overlap of Atomic Orbitals | The symmetry requirements for overlap to produce a bonding/antibonding interaction are discussed. Orbitals not having compatible symmetries do not interact. | Isosurfaces for pairs of orbitals are displayed and allowed to overlap in order to determine whether the orbital symmetries permit a bonding/antibonding interaction. |
| Bonding in the Hydrogen Molecule | The overlap of two hydrogen 1s orbitals to form a sigma bond in the H2 molecule is illustrated. | Electron density and isosurface plots are used to illustrate the interaction between two hydrogen atoms as the two atoms are brought close together. The energy diagram is used to predict various properties of the H2 molecule. |
| Molecular Orbital Diagrams | The structure and use of a molecular orbital diagram is explained. | Isosurfaces of the various atomic and molecular orbitals are displayed for a series of molecules (see below). Comparison of the atomic and molecular orbitals permits determination of the which atomic orbitals interacted to form the molecular orbital. This page displays the H2 molecular orbital diagram and isosurfaces. |
| Molecular Orbital Diagram: Hydrogen Fluoride (HF) | The molecular orbital diagram for hydrogen fluoride is displayed. Clicking on an orbital on the diagram displays the isosurface for the orbital. | |
| Molecular Orbital Diagram: Nitrogen (N2) | The molecular orbital diagram for dinitrogen is displayed. Clicking on an orbital on the diagram displays the isosurface for the orbital. | |
| Molecular Orbital Diagram: Fluorine (F2) | The molecular orbital diagram for difluorine is displayed. Clicking on an orbital on the diagram displays the isosurface for the orbital. | |
| Molecular Orbital Diagram: Carbon Monoxide (CO) | The molecular orbital diagram for carbon monoxide is displayed. Clicking on an orbital on the diagram displays the isosurface for the orbital. | |
| Molecular Orbital Diagram: Nitric Oxide (NO) | The molecular orbital diagram for nitric oxide is displayed. Clicking on an orbital on the diagram displays the isosurface for the orbital. | |
| Molecular Orbital Diagram: Carbon Dioxide (CO2) | The molecular orbital diagram for hydrogen fluoride is displayed. Clicking on an orbital on the diagram displays the isosurface for the orbital. | |
| Molecular Orbital Diagram: Water (H2O) | The molecular orbital diagram for water is displayed. Clicking on an orbital on the diagram displays the isosurface for the orbital. |
| Topic | Concepts | Experiment |
|---|---|---|
| Heating Curve | The processes that occur when a substance is heated are explained. | A heating curve is recorded for a substance, which is displayed to illustrated the accompanying phase changes. The viewer is asked to determine the melting point, boiling point, and enthalpies of fusion and vaporization. |
| Vapor Pressure | The liquid-gas and solid-gas equilibria are examined and the Claussius-Clapeyron is presented. | The vapor pressure of ethanol is measured at various temperatures. A Classius-Clapeyron plot is prepared, and the viewer is asked to determine the normal boiling point and standard enthalpy and entropy of vaporization for ethanol. |
| Phase Diagram: Part 1 | The properties of a phase diagram are described. | The viewer is asked to determine the stable phase at various temperatures and pressures. |
| Phase Diagram: Part 2 | The effect of crossing a phase line in a phase diagram is discussed. | A sample is heated isobarically such that the process crosses a phase line in the phase diagram. The viewer is asked to determine the sublimation temperature at the experimental pressure. |
| Phase Diagram: Part 3 | The effect of crossing a phase line in a phase diagram is discussed. | A sample is compressed isothermally such that the process crosses a phase line in the phase diagram. The viewer is asked to determine the pressure at which the phase change occurs at the experimental temperature. |
| Phase Diagram: Part 4 | The triple point is defined and its significance is discussed. | Temperature or pressure changes are used to drive a substance through the triple point. The viewer is asked to determine the triple-point temperature and pressure. |
| Phase Diagram: Part 5 | The critical point is defined and its significance is discussed. | The transition between a liquid and gas is examined via two different routes, one of which crosses a phase line and one of which does not (passing through the super-critical region instead). Colors are used to represent the sample density and illustrate how it is possible to convert a sample from a liquid to a gas (or vice-versa) without producing a phase-change reaction. |
| Phase Diagram | The features of a phase diagram are described. | A phase diagram is presented along with a sample confined in a cylinder with a movable barrier. The viewer may alter the temperature and pressure of the sample in order to explore the features of the phase diagram. |
| Topic | Concepts | Experiment |
|---|---|---|
| Spectrophotometry | The basic principles of spectrophotometry and the operation of a spectrophotometer are explained. | The transmittance and absorbance are measured for a sample. A blank is used to calibrate the spectrophotometer. |
| Absorbance Spectrum | The absorbance spectrum is described and its importance explained. | The absorbance spectrum for a sample is measured. |
| Effect of Cell Path Length | The significance of the cell path length is discussed. | The effect of the cell path length on transmittance and absorbances is explored. |
| Effect of Concentration | The significance of the analyte concentration is discussed. | The effect of the analyte concentration on transmittance and absorbances is explored. |
| Beer's Law | Beer's Law is presented and explained. | A plot of absorbance vs concentration is prepared, and the molar absorptivity is determined from the slope of the plot. |
| Analysis of an Unknown Solution | The construction of a calibration curve is described, and the use of a calibration curve in determining the analyte concentration in an unknown solution is explained. | A calibration curve is prepared and used to determine the analyte concentration in an unknown solution. |
| Topic | Concepts | Experiment |
|---|---|---|
| Carbon-Hydrogen Elemental Analysis | The determination of the weight percents of carbon and hydrogen in a sample is described. | The weight percents of carbon and hydrogen in an unknown compound are determined, and this information is used to determine the empirical formula. The empirical formula and molecular weight of the unknown compound are employed to determine the molecular formula. |
| Topic | Concepts | Experiment |
|---|---|---|
| Network Solids | The distinctions between ionic, molecular, metallic, and network solids are discussed. | Structures are shown for diamond, graphite, buckminsterfullerene, and cristobalite (silica) and questions are asked about the chemical bonding in these solids. Electron density plots for CO2 and SiO2 are used to illustrate differences in chemical bonding that produce the radically different physical properties of these compounds. |
| Holes in Closest-Packed Structures | The existence and properties of holes in closest-packed structures are discussed. | |
| Trigonal Hole | The geometry of a trigonal hole is described. | A virtual reality representation of three atoms forming a trigonal hole is presented, and the viewer is asked to calculate the rhole/r ratio. |
| Tetrahedral Hole | The geometry of a tetrahedral hole is described. | A virtual reality representation of four atoms forming a tetrahedral hole is presented, and the viewer is asked to calculate the rhole/r ratio. |
| Octahedral Hole | The geometry of an octahedral hole is described. | A virtual reality representation of six atoms forming an octahedral hole is presented, and the viewer is asked to calculate the rhole/r ratio. |
| Cubic Hole | The geometry of a cubic hole is described. | A virtual reality representation of eight atoms forming a cubic hole is presented, and the viewer is asked to calculate the rhole/r ratio. |
| Holes in the Cubic Closest-Packed Structure | An interactive virtual reality representation of a cubic closest-packed structure is presented, and the viewer is asked to determine types of holes present in the structure and the number of each type in the unit cell. | |
| Holes in the Hexagonal Closest-Packed Structure | An interactive virtual reality representation of a hexagonal closest-packed structure is presented, and the viewer is asked to determine types of holes present in the structure and the number of each type in the unit cell. | |
| Structure of Ionic Solids | The factors governing the structure of ionic solids composed of monatomic ions are discussed. | |
| Structure of Wurtzite | The crystal structure of Wurtzite is described. | A virtual reality representation of the crystal structure of Wurtzite is presented, and the viewer is asked to examine various properties of the structure. |
| Structure of Zinc Blende | The crystal structure of Zinc Blende is described. | A virtual reality representation of the crystal structure of Zinc Blende is presented, and the viewer is asked to examine various properties of the structure. |
| Structure of Rutile | The crystal structure of Rutile is described. | A virtual reality representation of the crystal structure of Rutile is presented, and the viewer is asked to examine various properties of the structure. |
| Structure of Sodium Chloride | The crystal structure of sodium chloride is described. | A virtual reality representation of the crystal structure of sodium chloride is presented, and the viewer is asked to examine various properties of the structure. |
| Structure of Cesium Chloride | The crystal structure of cesium chloride is described. | A virtual reality representation of the crystal structure of cesium chloride is presented, and the viewer is asked to examine various properties of the structure. |
| Structure of Fluorite | The crystal structure of Fluorite is described. | A virtual reality representation of the crystal structure of Fluorite is presented, and the viewer is asked to examine various properties of the structure. |
| Topic | Concepts | Experiment |
|---|---|---|
| Simple Cubic | The geometry of the simple cubic unit cell is described. | A virtual reality depiction of the simple cubic unit cell allows the structure of the solid to be visualized. An animation illustrates the number of atoms contained in the unit cell. |
| Body-Centered Cubic | The geometry of the body-centered cubic unit cell is described. | A virtual reality depiction of the body-centered cubic unit cell allows the structure of the solid to be visualized. An animation illustrates the number of atoms contained in the unit cell. |
| Face-Centered Cubic | The geometry of the face-centered cubic unit cell is described. | A virtual reality depiction of the face-centered cubic unit cell allows the structure of the solid to be visualized. An animation illustrates the number of atoms contained in the unit cell. |
| Hexagonal Closest-Packed Structure | The geometry of the unit cell of the hexagonal closest-packed structure is described. | A virtual reality depiction of the hcp unit cell allows the structure of the solid to be visualized. An animation illustrates the number of atoms contained in the unit cell. |