Online Chemistry Experiments :Online Chemistry Experiments Venkat Chebolu, Ph. D.
Associate Professor of Chemistry
Jefferson Community College
Watertown, NY 13601
List of Experiments :List of Experiments Observations of Chemical Changes
Laboratory Techniques and Measurements
Separation of a Mixture of Solids
Properties of Gases
Liquids and Solids
Physical and Chemical Properties
Ionic Reactions
List of Experiments (contd.) :List of Experiments (contd.) Stoichiometry of a Precipitation Reaction
Caloric Content of Food
Determination of Water Hardness
Le Chatelier’s Principle
Observations of Chemical Changes :Observations of Chemical Changes NaHCO3 + HCl
HCl + Bromothymol Blue (BTB)
NH3 + BTB
NaOCl + KI observe and test with starch
KI + Pb(NO3)2
NaOH + Phenolphthalein
HCl + Phenolphthalein
CuSO4 + NH3
Laboratory Techniques and Measurements :Laboratory Techniques and Measurements Length of various objects
Temperature of boiling water and ice-water mixture
Volume of water in a graduated cylinder
Number of drops of water from a micropipet in 1 mL (graduated cylinder)
Mass measured to 0.1g on a digital scale
Density of liquids and solutions
Laboratory Techniques and Measurements (contd.) :Laboratory Techniques and Measurements (contd.) Density of Solid by Water Displacement
Density of Solid by Archimedes’ Principle
Separation of a Mixture of Solids :Separation of a Mixture of Solids Mixture of Iron Filings, Sand, Benzoic Acid and Salt
Iron filings separated by using a magnet
Sand separated by dissolving the Benzoic Acid and salt in hot water
Benzoic Acid separated by cooling in an ice-bath and filtration of resulting crystals
Salt isolated by evaporation of salt solution (filtrate) at room temperature
Properties of Gases :Properties of Gases Gas is collected by displacement of water in a pipet bulb.
H2 is generated by reacting (1)Zn and (2)Mg with HCl.
O2 is generated from H2O2 and MnO2
CO2 is generated from NaHCO3 and HCl
H2 is tested by blowing it over a lit match
Properties of Gases (contd.) :Properties of Gases (contd.) O2 is tested by inserting a lit toothpick into the pipet bulb
Mixture of H2 and O2 collected in a pipet bulb is tested with a lit match as well
CO2 is tested with lime water and with BTB and with a lit toothpick
Gas evolved when Alka-Seltzer is dissolved in water is tested just like CO2
Liquids and Solids :Liquids and Solids B.P. of isopropyl alcohol is determined by inverting a closed-end capillary tube into 1 ml of the alcohol in a test tube.
M.P. of acetamide is determined by filling a closed-end capillary tube with the solid and noting the temperature of the water bath when the solid melts.
Physical and Chemical Properties :Physical and Chemical Properties Substances tested include Mg, Cu, Zn, MgO, CuCO3, Cu(NO3)2 and NaCl
Tests include
Color
Odor
Effect of heating in a test tube
Solubility in Cold and Hot water, and litmus test
Reaction with dilute HCl
Reaction with dilute NaOH
Ionic Reactions :Ionic Reactions In plate wells, each of the aqueous solutions of Co(NO3)2, Cu(NO3)2, Fe(NO3)2, Ba(NO3)2, and Ni(NO3)2 are reacted separately with solutions of Na3PO4, NaHCO3, NaI, Na2SO4, NaCl, Na2CO3 and NaOH
Evidence of Chemical reaction is to be noted
Net ionic equations to be written for chemical reactions occurring
Stoichiometry of a Precipitation Reaction :Stoichiometry of a Precipitation Reaction Aqueous solutions of Na2CO3 and CaCl2.2H2O in a 1:1 molar ratio are reacted and the resulting precipitate of CaCO3 is collected quantitatively.
Caloric Content of Food :Caloric Content of Food Food items such as Marshmallow, Peanut, Popcorn, Potato chip and Walnut are burnt, and the heat generated is used to heat a known mass of water in a beaker
Heat generated per gram of each item burnt is calculated
Determination of Water Hardness :Determination of Water Hardness Calmagite indicator is used to detect presence (red) or absence (blue) of Ca+2 and Mg+2 in water samples.
In a plate well, calmagite is added to water samples of known and unknown hardness. The number of drops of EDTA needed to turn the solution blue in each case is determined.
Le Chatelier’s Principle :Le Chatelier’s Principle Mg(OH)2 Mg+2 + 2 OH-1
In a plate well, an aqueous solution of MgCl2, to which phenolphthalein is added, is treated with an aqueous solution of NaOH till the solution turns pink. Then, HCl is added till the solution turns colorless.
A part of this solution is sucked into a pipet bulb and held in cold and hot water to see how temperature affects this equilibrium.
Le Chatelier’s Principle (contd.) :Le Chatelier’s Principle (contd.) HSO4-1 + H2O H3O+ + SO42-
Thymol blue is used as an indicator to decide where the equilibrium lies.
Na2SO4 and NaHSO4 are added successively to an aqueous solution of NaHSO4 to determine direction of equilibrium shift.
This solution is placed in a pipet bulb and placed in hot and cold water baths to determine the effect of temperature on this equilibrium
Differences :Differences Filter funnel supported in a paper cup placed in a coffee cup
Rubber policeman at the end of the glass rod to wash down precipitates stuck to the walls of the containers not used
Cutting, bending and drawing glass experiment not being performed online.
Bunsen Burner and Fisher burner experience missing
Differences (contd.) :Differences (contd.) Inserting glass tubing into tygon tubing is not experienced online
No experience using a triple beam balance
Spectroline pipet filler not used online
No experience with coffee cup calorimetry
No sublimation of Naphthalene online
No experience with simple distillation
Differences (contd.) :Differences (contd.) No experience with vacuum (Buchner funnel) filtration
No experience with gravimetric experiments using crucibles and crucible tongs and heating to constant mass
Charles law verification experiment not done online
Determining solubility of a salt in water and determining whether a solution conducts electricity
Differences (contd.) :Differences (contd.) Factors affecting reaction rates lab is not done online
Mg is dropped into different strong and weak acids of the same concentration
Zn, Mg and Cu are dropped into solutions of HCl
Iodine clock reaction rate is studied as a function of reactant concentrations
Crushed and uncrushed marble is reacted separately with HCl
Zn is added to HCl at different temperatures
Differences (contd.) :Differences (contd.) In F2F setting, there is a three hour time limit for the lab. Some students do feel pressured to complete the lab in that time or to come back later to complete the lab.
In the online format, there is really no time limit and everyone works at their own pace resulting in observations such as the following:
An unidentified aroma was evident during the entire separation experiment. The benzoic acid crystal formations seemed quite intriguing that resembled pieces of cut fiberglass or MSG. Very reflective and lustrous, but seemed to attach itself to other substances pretty easily. Salt crystal formation gathered to several clumps instead of an even formation at the cup’s bottom.
Differences (contd.) :Differences (contd.) In the F2F situation writing a lab report usually entails filling in the blanks or boxes in a pre-organized lab format that accompanies each lab followed by answering post laboratory questions. A lot of the answers received are very similar as they are provided after consultation with class peers.
In the online format, the lab write-up is expected to include Title, Purpose, Procedure, Data Tables, Observations, Questions and Conclusions. The organization of the Data Tables and Observations is for the most part left for the students to figure out.
Differences (contd.) :Differences (contd.) In the F2F situation, when a single answer is proposed for a question, that answer is usually embraced by the rest of the class and no more thinking occurs without intervention.
In the online mode, everyone is thinking on their own until they find some answer to the question. This results in a diversity of answers as evidenced by the following example.
Differences (contd.) :Differences (contd.) Answers provided for why the boiling point of water observed is different from 1000C:
My water boiled at the expected temperature - perhaps this is an experimental error on my behalf
The material of the pan that I boiled the water in may have had an effect on the boiling point of water. Also, the thermometer could be a little off
The water boiled at a different temperature because the water was in a smaller container and the heat was directly applied
Observations :Observations No instructor intervention after experiment is started.
Students are forced to get creative.
When graded lab report is returned, students’ understanding of the situation is much better because they have invested their best thinking into the problem.
A sense of discovery takes hold of the students, especially when they seemed to have followed the procedure and what they see is different from what they expect.
Observations (contd.) :Observations (contd.) Repeating a lab after they have messed up is very rarely possible.
Through these labs students are certainly getting a very good hands on experience in manipulating chemicals and honing their observation skills. This is very similar to the experience a student gets in a face-to-face lab course.
Student Reactions :Student Reactions While performing this (Ionic reactions lab) I learned how to recognize ionic reactions and see when they can occur by mixing different substances. I enjoyed performing this experiment and my confidence of working in the laboratory has improved
Student Reactions (contd.) :Student Reactions (contd.) This lab demonstrates that there are many different ways to detect ionic reactions. These reactions become visible to the chemist as a color change, precipitate, or release of gas. It is very interesting to note how the exchange of positive and negative ions in two reacting solutions will change the solubility of a chemical and form a precipitate
Student Reactions (contd.) :Student Reactions (contd.) I found this (Caloric Content of Food) lab to be very interesting. I never knew it was possible to determine the energy content of a food item by burning it until I completed this experiment. Although I did find that particularly the marshmallow in this experiment lit on fire quickly and in a matter of seconds the flame became a bit out of control, so just a fore warning to those who have not completed the lab yet.
Student Reactions (contd.) :Student Reactions (contd.) This lab (Caloric Content of Food) has taught the process of finding the energy content of food by burning a portion of a certain food and taking the heat given off by the food and adding it to a known mass of water. My observations have also taught me that a longer burning food will probably lead to a higher caloric food, based on the peanut burning longer than the marshmallow.
Student Reactions (contd.) :Student Reactions (contd.) I found this (Water hardness) experiment very interesting. I especially enjoyed the fact that this is chemistry that I can in fact relate to in my every day life. Every one needs water to survive. I did find it quite awkward to stir the solution with a toothpick. However, in determining the water hardness of my local water it has made me consider the possibility of investing in a water softener. I am confident in my skills now and know that if I desire I can now test the local water supply wherever I go.
Student Reactions (contd.) :Student Reactions (contd.) This lab (Water hardness) was very interesting. The water in the area where I tested has always been a concern of mine. For me it was and still is very hard to get used to, the quality affecting everything from my food to my shower. In passing I have heard others say that water was hard but it was nice to actually test it and have proof of how hard the water actually was.
Conclusion :Conclusion The kit is certainly helping students get the kind of hands-on experience that a F2F Chemistry lab provides. While certainly not providing each and every technique, these experiments go a long way in providing a medium for the students to get a first hand experience of learning Chemistry by doing. Further, it does provide a medium for students to think about the experiment they are performing and draw conclusions as in a regular brick and mortar Chemistry Lab.
Acknowledgements :Acknowledgements Ron Krempasky AHS for this opportunity
Linda Jeschofnig AHS for abstract writing
Peter Jeschofnig AHS for co-presenting
Vela Chebolu WHS for Powerpoint Design