Information | Online Chemistry Labs

Virtual Experiments | Online Chemistry Labs

Laboratory Techniques   For learning objectives of this lab, click here.

An introductory lab that helps familiarize students with the virtual laboratory environment, and works through the operation of the mouse, the balance, and some additional apparatus. The lab explains the virtual lab flow and general rules about entering data and discussion answers.

Required background: Students will need basic computer skills (using the mouse and its buttons, a keyboard, etc) and understand the use of an analytical balance to measure mass.

Error and Standard Deviation    For learning objectives of this lab, click here.

This experiment provides an introduction to error analysis by calculating the standard deviation of a group of measured values that exhibit random deviation about an average value.

Required background: Students should be able to: compute an average (mean) value, evaluate algebraic expressions and construct a table of values; use the virtual analytical balance to measure mass. Experience in the use of a spreadsheet program to assist in the calculations is helpful but not required.

Spreadsheets and Linear Regression      For learning objectives of this lab, click here.

This experiment provides an introduction to the use of a spreadsheet program to analyze an experimental data set by creating a data table and plotting the data, followed by determining the slope, intercept, and equation for the best-fit line using the method of least squares. The best fit linear equation is used to predict new values.

Required background: Students should be familiar with the basic operations in a spreadsheet program such as OpenOffice Calc or Microsoft Excel. Instructions will be provided to install the free OpenOffice suite of programs if needed. Students should know how to switch back and forth between two different programs running in computer memory and be able to keep a useful lab notebook record during the experiment.

Combustion       For learning objectives of this lab, click here.

This experiment simulates a typical carbon-hydrogen analysis procedure used to determine the empirical formula of a combustible organic compound. A measured mass of a pure compound is burned in excess oxygen in a combustion chamber, and the resulting CO2 and water vapor are captured in traps. The discussion guides the analysis of trap mass changes to the calculation of an empirical formula. Both known and unknown compounds are analyzed in the experiment.

Required background: Students should be able to use the virtual analytical balance to determine masses, perform stoichiometric calculations to convert moles to masses and v.v., and understand the difference between an empirical and a molecular formula.

Metal + HCl       For learning objectives of this lab, click here.

This experiment uses the pressure of hydrogen produced by the reaction of a known mass of a metal with excess hydrochloric acid to determine the atomic mass of the metal. Both known and unknown compounds are analyzed in the experiment.

Required background: Students should be able to balance chemical reactions to predict a mole ratio of reactants and products. Knowledge of the ideal gas equation is also required to convert pressure data into moles of gas.

Calorimetry     For learning objectives of this lab, click here.

This experiment uses a virtual calorimeter to measure the heat evolved when a measures mass of a combustible substance is burned in an excess of oxygen gas. The goal is to determine the heat of combustion per mole of a known and unknown compound.

Required background: Students should be able to extrapolate graphical data to obtain a measured temperature change under conditions of competing trends and calculate heat changes using simple thermodynamic relations.

Synthesis and TLC       For learning objectives of this lab, click here.

Students explore the concepts of limiting reagents and stoichiometric ratios of reactants by running a simple 1:1 organic addition reaction and using thin layer chromatography on the product obtained to determine if either reagent was used in excess.

Required background: Students should be familiar with concepts such as stoichiometric ratios of reactants and limiting reagents. Also required are calculating a liquid mass from its density and volume, calculating moles from mass and molecular weight, and a basic understanding of solvent-solute interactions.

Absorbance    For learning objectives of this lab, click here.

This experiment introduces the principles of absorption spectrophotometry and use of the Beer-Lambert Law to determine concentration from a working curve of absorbance vs. concentration.

Required background: Students should be familiar with the properties of light and the electromagnetic spectra, calculations involving molarity, and the use of spreadsheets to plot data and determine the slope, intercept, and equation of a best-fit line.

NMR        For learning objectives of this lab, click here.

This experiment uses 19F nuclear magnetic resonance to determine the structures of several sulfur fluorides. The number of peaks and their relative intensities for a series of compounds containing fluorine and methyl ligands around a central sulfur atom are used to assign reasonable coordination geometries (octahedral, square planar, and tetrahedral), and ligand configurations (cis and trans) configurations.

Required background: Students should be familiar with molecular geometries of molecules containing a single central atom surrounded by 4 to 6 ligands. No prior experience with NMR is required.

Freezing Point Depression       For learning objectives of this lab, click here.

This experiment determines the freezing points of pure benzophenone and of a mixture of another organic substance dissolved in benzophenone. As these melted mixtures are slowly cooled, the melts begin to freeze, and the colligative property of freezing point depression is studied quantitatively.

Required background: Students should be familiar with the colligative property of freezing point depression, the definition of molality, and the parameters relating freezing point depression to molality.

Osmotic Pressure      For learning objectives of this lab, click here.

This experiment introduces semi-permeable membranes as a means of measuring the osmotic pressure of aqueous solutions of several soluble substances. A membrane osmometer is used for these quantitative measurements.

Required background: Students should be familiar with the colligative property of osmotic pressure, the definition of molarity, and the parameters relating osmotic pressure to molarity.

Thin Layer Chromatography      For learning objectives of this lab, click here.

This experiment studies in greater depth the technique of Thin Layer Chromatography (TLC) that was introduced as a tool in the Synthesis experiment. TLC relies upon the interactions between a solvent, a solute, and a stationary substrate. The competition between solvent and solute molecules for sites on the stationary phase determines the relative rates at which different solutes move along the substrate while being transported by the solvent, allowing different substrates to be separated and identified.

Required background: Students should be familiar with the shapes of organic molecules, chemical bond polarity, the role of molecular shape in determining overall molecular polarity, and functional groups in organic molecules. Precise use of the mouse to click and drag objects in the virtual lab will be required.

Iodine Clock     For learning objectives of this lab, click here.

Students will set up and run multiple instances of the classic "iodine clock" reaction with different reagent concentrations to evaluate the reaction rate law exponents.

Required background: Students should be familiar with standard kinetic terms such as reaction rate, rate law, and  the relationship between reaction time and reaction rate. Students need to calculate molarities and be able to use the expression M1V1 = M2V2 to calculate the effects of dilution. Use of the log function and use of a spreadsheet program to plot data and determine a slope are required.

Titration I        For learning objectives of this lab, click here.

This experiment introduces the concept of "standardization" of a solution by use of a primary standard reagent and an acid-base titration. The pH of an acid solution is monitored using a pH electrode and a titration curve plotted in real time (pH vs volume of added base). The experimental determination and significance of the "endpoint" is illustrated.

Required background: Students should be familiar with the definitions of strong acid/base and weak acid, the reaction of an aqueous acidic solution with a basic solution, the definition of pH, how to measure the mass of a reagent to be dissolved in solution, how to calculate concentration (Molarity) of a solution based upon the calculated moles of reagent and volume of solution, as well as be able to use the expression M1V1 = M2V2 to calculate the concentration of a reagent involved in a known reaction with a given solution, and be able to calculate an average and the standard deviation of several measurements.

Titration II       For learning objectives of this lab, click here.

This experiment uses the titration technique introduced in the Titration I experiment to measure the concentration of a weak acid solution using a strong base of known concentration. From these results, the weak acid's molar mass and acid dissociation constant, Ka, are determined.

Required background: Students should be familiar with the titration scheme from the Titration I experiment, the definition and general behavior of weak acids, the use of Ka in calculating pH, and how to use the measured endpoint of a titration in calculations.

Weak Acid Equilibrium        For learning objectives of this lab, click here.

This experiment studies in depth the behavior of a weak acid and its conjugate base by forming aqueous solutions of several known compositions and measuring pH. Buffer solutions are created and buffer capacity described. Each prepared solution is tested by adding small amounts of strong base to observe relative pH changes.

Required background: Students should be familiar with the definitions of weak acid, conjugate base, buffer, strong base, pH, and how to calculate solution concentrations.

Electroplating      For learning objectives of this lab, click here.

This experiment involves the reduction of metal ions in an aqueous solution to plate metal on an electrode. The mass of plated metal is measured and compared to the amount of electric charge used to reduce the ions. A known metal is tested, and the identity of an unknown metallic element is determined by calculating the charge required to plate a measured metal mass.

Required background: Students should be familiar with oxidation and reduction, half-reactions, Faraday's Law, The relationship of current and charge, and the dissociation of ionic compounds into ions in solution.

Potentiometry       For learning objectives of this lab, click here.

This experiment allows students to generate electrochemical cells with separate half-reactions and measure the cell potentials. Observed values are compared to literature values, the effect of concentration is evaluated, and an unknown metal ion in solution is identified by the cell potential produced against a known half-cell.

Required background: Students should be familiar with oxidation and reduction, half-reactions, and calculations involving the Nernst equation.

Nuclear Chemistry      For learning objectives of this lab, click here.

This experiment uses neutron activation in a virtual nuclear reactor to measure the decay half-life of two unstable isotopes.

Required background: Students should be familiar with the concepts of exponential decay, the first order rate law, half-life, and the use of logarithms.

Entropy      For learning objectives of this lab, click here.

This experiment extends the Potentiometry experiment by adding temperature control and variation. By measuring the potential of several electrochemical cells at different temperatures, the Gibbs free energy, enthalpy, and entropy changes for reactions are determined.

Required background: Students should be familiar with the Potentiometry experiment, the use of free energy of formation, enthalpy of formation, and entropy, calculations using the relationships ΔG=ΔH‐TΔS and ΔG=-nFE. Students will use a spreadsheet program to plot data and obtain the slope and intercept for a best-fit line.

Density      For learning objectives of this lab, click here.

This experiment introduces density as an intensive property of a few regular solids. After measuring the mass and determining the volume of objects, the student calculates the densities. Gold alloys are used as examples of materials with similar appearance but different densities.

Required background: Students should be familiar with the formula for the volume of common regular objects (cube, cylinder, and sphere).

Vitamin-C Analysis     For learning objectives of this lab, click here.

This experiment provides an introduction to the analysis of concentration without background in stoichiometry. Titration to a colored endpoint is the method. After standardization of the titrant DCP using a vitamin-C solution of known concentration, the student proceeds to determine the vitamin-C content in drinks, juices, and fruits.

Required background: Students need only simple arithmetic skills and the ability to perceive color change to red-pink.