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 About Virtlab
Carl Spitzweg (1808-1885) "Der Alchemist"

 Virtlab Demonstration
Pietro Longhi (1701 - 1785) "The Alchymist"

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Stoichiometry Resources For Students And Teachers!

Molecular weights, moles, mole fractions, limiting reagents, theoretical yields, percent composition, empirical formulas.

What is Virtlab?

  • Virtlab is a laboratory manual that uses laboratory simulations to perform its experiments. Simulations are also available as electronic spreadsheets that you or your students can build and explore.

  • Our authors pioneered this approach and have refined it over many years. We are among the first educators in the world to integrate personal computers and science education.

  • Virtlab is divided into two sections. "Free Virtlab" shows you how the process works. "Full Virtlab" offers you our complete storyline. If you are uncertain about the value you will find in Virtlab then subscribe for one month at US$ 4.95. If you like what you see then extend your subscription for six months using the far more cost effective 6 month subscription of US$14.95.

Chapter 2 - Stoichiometry:

  • Exercise 2.1 - Molecular Weights And Moles: Even the simplest concepts can be challenging to beginners. In the laboratory on your left, students pour a substance of known molecular weight into a pan balance. The pan balance records grams, moles and number of atoms. You may be surprised at how many beginning students achieve a new level of understanding when they see that pouring 18.02 grams of H2O or 58.44 grams of NaCl both yield 1 mole of molecules. (Exercise 2.1 is part of "Free Virtlab".)

  • Exercise 2.2 - Mole Fractions: In the laboratory (not shown) an array of flasks deliver increasing amounts of different substances into an analyzer where the mole fraction of each substance is displayed in a bar chart. Students discover that, for example, because a molecule of H2O masses less than a molecule of CH3OH, 1 g of H2O contains more molecules than 1 g CH3OH. The mole fraction of H20 in the mixture is therefore greater. (Exercise 2.2 is part of "Full Virtlab".)

  • Other Exercises: Other exercises in Chapter 2 explore "Limiting Reagents and Theoretical Yields", "Percent Composition", and "Empirical Formulas". Some of the exercises do not have a visual laboratory but involve calculations designed and explored in electronic spreadsheets. (These exercises are part of "Full Virtlab".)

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Virtlab is based on the simulations and guided exercises found in N. Simonson & Company's pioneering text: Dynamic Models in Chemistry by Daniel E. Atkinson (University of California, Los Angeles, CA), Douglas C. Brower, and Ronald W. McClard (Reed College, Portland, OR). Laboratories are also under development for Dynamic Models in Physics (Volume I: Mechanics) by Frank Potter (University of California, Irvine, CA), and Charles W. Peck (California Institute of Technology, Pasadena, CA), and Dynamic Models in Biochemistry by Daniel E. Atkinson (University of California, Los Angeles, CA), Steven G. Clarke (University of California, Los Angeles, CA), and Douglas C. Rees (California Institute of Technology, Pasadena, CA)

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A new exercise Simple and Fractional Distillation now exists. Other recent simulations include explorations of stoichiometry (moles, mole fractions, limiting reagents), the Ideal Gas Law and the Equation of State, Charles Law, Boyles Law, Raoults Law, and acidic dissociation (including isoelectric points). Stoichiometry is an important subject and Charle's law, Boyle's Law, together with Raoult's Law and acid base titrations are important matters. Daltons Law of Partial Pressures, sometimes called Dalton's Law of partial pressures play crucial roles can help in understanding fractional distillation. dalton's law of partial pressures (daltons law of partial pressures) should be understood by all students. Along with fractional distillation. Will you be ready for acid base titration or acid base titrations. We hope so. And don't forget or stoichiometry exercises.