Demonstrating close-packing of atoms using spherical bubble gums

In this paper, the use of spherical bubble gums (Gum Balls) to demonstrate the close-packing of atoms and ions is presented. Spherical bubble gums having distinctive colours were used to illustrate the different layers in variety of crystalline packing and the formation of tetrahedral and octahedral holes. Students with hands-on experience of building the different packing models could better understood the close-packing of atoms

Vegetables for building molecular models

An exciting classroom activity involving the construction of molecular models and building hybrid orbitals is presented in this paper. Basic molecular geometries were built by connecting different types of vegetables using bamboo skewers. Vegetable of different shapes were used to describe the hybridization of atomic orbitals. This exercise is suitable for high school and undergraduate chemistry students. The activity helps students to apply Valence Shell Electron Pair Repulsion (VSEPR) theory to envisage the basic shapes of molecules and to conceptualize the hybridization of the atomic orbital

Feasibility of Using an Electrolysis Cell for Quantification of the Electrolytic Products of Water from Gravimetric Measurement

A gravimetric method for the quantitative assessment of the products of electrolysis of water is presented. In this approach, the electrolysis cell was directly powered by 9 V batteries. Prior to electrolysis, a known amount of potassium hydrogen phthalate (KHP) was added to the cathode compartment, and an excess amount of KHCO3 was added to the anode compartment electrolyte. During electrolysis, cathode and anode compartments produced OH−(aq) and H+(aq) ions, respectively. Electrolytically produced OH−(aq) neutralized the KHP, and the completion of this neutralization was detected by a visual indicator color change. Electrolytically produced H+(aq) reacted with HCO3−(aq) liberating CO2(g) from the anode compartment. Concurrent liberation of H2(g) and O2(g) at the cathode and anode, respectively, resulted in a decrease in the mass of the cell. Mass of the electrolysis cell was monitored. Liberation of CO2(g) resulted in a pronounced effect of a decrease in mass. Experimentally determined decrease in mass (53.7 g/Faraday) agreed with that predicted from Faraday’s laws of electrolysis (53.0 g/Faraday). The efficacy of the cell was tested to quantify the acid content in household vinegar samples. Accurate results were obtained for vinegar analysis with a precision better than 5% in most cases. The cell offers the advantages of coulometric method and additionally simplifies the circuitry by eliminating the use of a constant current power source or a coulometer

Interlocking Toy Building Blocks as Modules for Undergraduate Introductory and General Chemistry Classroom Teaching

Interlocking toy building blocks (e.g., Lego) as chemistry teaching modules are presented. Interlocking building blocks were assembled on a baseplate to depict chemistry concepts of Lewis structures, chemical bonding, conjugate acid-base pairs, types of chemical reactions, irregularity in ionization energy trends, and the decay of a radioactive isotope. The modules were presented to visualize these chemical concepts in undergraduate introductory and general chemistry classrooms. Modules were presented on a document camera in an online mode of delivery

Feasibility of Using an Electrolysis Cell for Quantification of the Electrolytic Products of Water from Gravimetric Measurement

© 2018 Samuel Melaku et al. A gravimetric method for the quantitative assessment of the products of electrolysis of water is presented. In this approach, the electrolysis cell was directly powered by 9 V batteries. Prior to electrolysis, a known amount of potassium hydrogen phthalate (KHP) was added to the cathode compartment, and an excess amount of KHCO3 was added to the anode compartment electrolyte. During electrolysis, cathode and anode compartments produced OH-(aq) and H+(aq) ions, respectively. Electrolytically produced OH-(aq) neutralized the KHP, and the completion of this neutralization was detected by a visual indicator color change. Electrolytically produced H+(aq) reacted with HCO3-(aq) liberating CO2(g) from the anode compartment. Concurrent liberation of H2(g) and O2(g) at the cathode and anode, respectively, resulted in a decrease in the mass of the cell. Mass of the electrolysis cell was monitored. Liberation of CO2(g) resulted in a pronounced effect of a decrease in mass. Experimentally determined decrease in mass (53.7 g/Faraday) agreed with that predicted from Faraday\u27s laws of electrolysis (53.0 g/Faraday). The efficacy of the cell was tested to quantify the acid content in household vinegar samples. Accurate results were obtained for vinegar analysis with a precision better than 5% in most cases. The cell offers the advantages of coulometric method and additionally simplifies the circuitry by eliminating the use of a constant current power source or a coulometer

Feasibility of Performing Concurrent Coulometric Titrations Using a Multicompartment Electrolysis Cell

© 2019 American Chemical Society. Feasibility of performing multiple coulometric titrations in a single course of electrolysis is presented. In these titrations, three pairs of cathode and anode compartments were connected with a network of electrodes and salt bridges. Passage of current through the cell caused concurrent electrolysis in cathode and anode compartments. Electrogenerated reagents produced in these compartments were used as titrants for quantifying the analyte samples. Endpoints of the titrations were determined from the visual color change of an indicator. The charge passing through the cell was monitored and Faraday\u27s laws of electrolysis were applied to assess the quantitative relation between the charge and analyte concentration. Experimentally determined coulombs required to titrate aqueous potassium hydrogen phthalate, MnO 4- , OH - , and S 2 O 32- were 0.100, 0.466, 0.103, and 0.0934 C, respectively. These results matched with estimated values of 0.0965, 0.482, 0.0965, and 0.0965 C, respectively. Agreement between the coulombs determined from experimental results and reaction stoichiometry suggests a feasible application of concurrent coulometric titrations. Efficacy of the method was tested for determining the active ingredients in household vinegar and vitamin C dietary supplement tablets. Quantities of acetic acid and ascorbic acid in these products were 5.1% and 980 mg, respectively, agreeing with the quantities determined from volumetric titrations (5.1% and 990 mg) and manufacturer\u27s label (5.0% and 1000 mg)

Feasibility of Performing Concurrent Coulometric Titrations Using a Multicompartment Electrolysis Cell

Feasibility of performing multiple coulometric titrations in a single course of electrolysis is presented. In these titrations, three pairs of cathode and anode compartments were connected with a network of electrodes and salt bridges. Passage of current through the cell caused concurrent electrolysis in cathode and anode compartments. Electrogenerated reagents produced in these compartments were used as titrants for quantifying the analyte samples. Endpoints of the titrations were determined from the visual color change of an indicator. The charge passing through the cell was monitored and Faraday’s laws of electrolysis were applied to assess the quantitative relation between the charge and analyte concentration. Experimentally determined coulombs required to titrate aqueous potassium hydrogen phthalate, MnO4–, OH–, and S2O32– were 0.100, 0.466, 0.103, and 0.0934 C, respectively. These results matched with estimated values of 0.0965, 0.482, 0.0965, and 0.0965 C, respectively. Agreement between the coulombs determined from experimental results and reaction stoichiometry suggests a feasible application of concurrent coulometric titrations. Efficacy of the method was tested for determining the active ingredients in household vinegar and vitamin C dietary supplement tablets. Quantities of acetic acid and ascorbic acid in these products were 5.1% and 980 mg, respectively, agreeing with the quantities determined from volumetric titrations (5.1% and 990 mg) and manufacturer’s label (5.0% and 1000 mg)

Interlocking Toy Building Blocks as Hands-On Learning Modules for Blind and Visually Impaired Chemistry Students

Interlocking toy building blocks (e.g., Lego) as chemistry learning modules for blind and visually impaired (BVI) students in high school and undergraduate introductory or general chemistry courses are presented. Building blocks were assembled on a baseplate to depict the relative changes in the periodic properties of elements. Modules depicting the electron configuration of an element and molecular orbital theory were also constructed. Modules were presented as a hands-on learning experience for a group of BVI students followed by a survey. Modules were also presented as classroom demonstration for an undergraduate general chemistry class of sighted students

Interlocking Toy Building Blocks as Hands-On Learning Modules for Blind and Visually Impaired Chemistry Students

Interlocking toy building blocks (e.g., Lego) as chemistry learning modules for blind and visually impaired (BVI) students in high school and undergraduate introductory or general chemistry courses are presented. Building blocks were assembled on a baseplate to depict the relative changes in the periodic properties of elements. Modules depicting the electron configuration of an element and molecular orbital theory were also constructed. Modules were presented as a hands-on learning experience for a group of BVI students followed by a survey. Modules were also presented as classroom demonstration for an undergraduate general chemistry class of sighted students