# Data-Driven Exercises

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The exercises are designed to provide supplemental exposure to select topics that are encountered in the chemistry curriculum. An attempt has been made to keep the exercises relatively short. The theoretical background descriptions are brief and include only those concepts and equations that are central to the assignment. Students should only attempt certain assignments after receiving a more thorough exposure to the prerequisite topics in class or through independent study. Students will need access to some type of quantitative analysis software to carry out most of the assignments. In designing these exercises, no attempt has been made to instruct students in the use of any particular software environment or computer platform, or how to otherwise accomplish common numerical methods. Consequently, students will need some prior training in an appropriate software environment before attempting most exercises.

• Adsorption Isotherms - Methylene Blue on Activated Carbon
Chemical reactions are often classified as being either homogeneous or heterogeneous. In the later case, the reactants and catalyst (if any) exist in different phases, and consequently the reaction occurs at the phase boundary. Many important industrial reactions fall into this category, including the classic Haber ammonia synthesis, whereby nitrogen and hydrogen gas are catalytically combined on a metal surface at elevated pressures.
• Analysis of the IR Spectrum of Carbon Monoxide
The infrared (IR) spectrum of carbon monoxide is analyzed in order to determine the rotational constant (B) of this diatomic.
• Azeotropic composition for cyclohexane and ethanol from gas chromatography data
The composition of a binary solution with lowest Gibbs free energy of mixing corresponds to the azeotrope. Gas chromatography data is used to calculate the Gibbs free energy of mixing for various cyclohexane and ethanol solutions. Based on the uncertainty of all the measurements and using error propagation techniques, the property is calculated with its associated uncertainty. This exercise is adequate for the undergraduate physical chemistry curriculum.
• Bartender's Conundrum - Partial Molar Volume in Water-Ethanol Mixtures
Every bartender knows well that mixing 50 ml of water with 50 ml of ethanol does not give an alcohol drink of 100 ml; the difference is called the excess volume. This excess volume can be expressed in terms of the mole fraction of either ethanol or water, and the magnitude of the excess volume provides a measure of non-ideal mixing of water and ethanol molecules. The existence of the excess volume indicates that molar volumes are non-additive.
• Determination of partial molar volumes in aqueous solutions of ionic compounds
Density data are presented for aqueous solutions of three ionic compounds. From this data graphs of the volumes of the solutions containing a fixed amount of solvent vs. moles of solute are constructed, and from these graphs the partial molar volumes with respect to the solutes are determined.
• Determination of Virial Coefficients for Argon Gas at 323 K
The pressure (P), volume (V), and temperature (T) of a given amount of gas can be used to calculate the compression factor (Z). Pressure-volume data is presented for argon gas at 323.15 K. The compression factor is calculated for each P-V data pair and a virial equation of state is subsequently fitted to the data, yielding the virial coefficients.
• Enzyme Kinetics - Alcohol Dehydrogenase Catalyzed Oxidation of Ethanol
Kinetic data is presented for the alcohol dehydrogenase catalyzed oxidation of ethanol to acetaldehyde. The results are analyzed within the context of the Michaelis-Menten mechanism for enzyme action.
• Fluorescence Lifetimes and Dynamic Quenching
Fluorescent lifetime data are presented for two aqueous systems that contain varying amounts of a quenching agent. A Stern-Volmer analysis is carried out on each data set and the bimolecular quenching rate constant is determined for each system.
• Hydrogen Ion Activities from pH Measurements
pH measurements are presented for a series of HCl solutions of increasing concentration. The data are analyzed to determine the activities and activity coefficients of the hydrogen-ion. The results are compared to theoretical predictions from the extended Debye-Hückel equation.
• Investigating molecular structure and the 1-octanol-water partition coefficient
The 1-octanol-water partition coefficient, which expresses the ratio of the concentration of a compound dissolved in 1-octanol to the concentration of that compound dissolved in water in an immiscible mixture of 1-octanol and water, is statistically analyzed for 196 organic compounds in order to assess how molecular structure is related to this property.
• Liquid-vapor Equilibria - ΔH and ΔS for Vaporization
Vapor pressure data is presented for two liquids over a given temperature range and the heat of vaporization and entropy change for vaporization are determined. What governs whether the equilibrium lies more toward the liquid phase or the gas phase in a particular system? Temperature is certainly expected to have an impact. As temperature rises, the increased kinetic motion of molecules tends to overcome intermolecular attractions and a greater fraction of the molecules will reside in the vapor.
• Osmotic Pressure and Polymer Molecular Weight Determination
Suppose you are given an unknown biomolecular substance, such as a protein, RNA strand, or polysaccharide, and you are then asked to determine the molecular weight of the substance. What experimental methods are available for determining the molecular weight of a large molecule (or perhaps a synthetic polymer or biopolymer)? One of the more precise techniques involves the measurement of osmotic pressure.
• Specific Heat Capacities and the Dulong-Petit Law
Specific heat capacity data for a wide range of elements are used to assess the accuracy and limitations of the Dulong-Petit Law.
• Standard Molar Entropy of Aluminum Oxide
Standard molar entropy is one of the most useful types of thermodynamic data for a substance. But how does one measure this property? Unfortunately, there is no instrument that directly measures entropy. Instead, values are determined indirectly through the measurement of constant pressure heat capacities (Cp).
• Statistical analyses of flash point and boiling point data for organic compounds
Flash point and boiling point data for 248 compounds, arranged in a homologous series, are analyzed by various statistical methods in order to investigate the correlation between these two properties and also how each property varies with molecular structure.
• Strain Energy in Organic Compounds - Bomb Calorimetry
Bomb calorimeter measurements are presented for cyclopropanecarboxylic acid and 1,4-cyclohexane-dicarboxylic acid and the heat of combustion is determined for both compounds. Students are then guided to learn about strain energy by comparing the results obtained for these two compounds.
• Viscosities of Simple Liquids - Temperature Variation
Viscosity (η) is a fluid property which indicates how resistant that fluid is to flow. Highly viscous liquids, like motor oil or molasses, take much longer to flow from their container than a relatively low viscosity liquid, like benzene or diethyl ether. To quantify viscosity, we will imagine our bulk fluid as consisting of a number of very thin layers. In order for the fluid to flow, a force will be required to slide these layers relative to one another.

This page titled Data-Driven Exercises is shared under a CC BY-NC-SA 4.0 license and was authored, remixed, and/or curated by Tandy Grubbs.