Type:
Solution Manual
Resource:
General Chemistry Atoms First Plus MasteringChemistry
Edition:
2nd Edition
Author(s):
John E. McMurry
To the Instructor: When looking through the instructor versions of the other laboratory manuals currently available, my first thought was that I wouldn’t have time to wade through even 10 percent of the material contained within them. The instructor versions often contained detailed discussions of concepts I didn’t need (I have a degree in chemistry too) and redundant materials already available in the student manual. The instructor versions also seemed to lack the kind of information that I would really like to have, e.g., potential problems that can occur when the students performed the experiments or notes on points to stress that I could give to my teaching assistants. So when designing this instructor manual, I tried to include all of the information and materials I would like to have and left out those materials that seemed unnecessary. For each experiment in the lab manual you will find the following in the instructor version:
A list of chemicals, equipment, and supplies Preparation instructions for chemicals and reagents as needed A discussion of points to stress and potential problems to be aware of when performing the experiments A key for the pre-laboratory assignments A key for the post-laboratory assignments
The keys provided do not include a grading scale as I believe that different instructors will want to emphasize different portions of the assignments and reports. The reports in the manual are already delineated as to what the students should be including and will be based on their experimental data so there is no key provided for them beyond the identity of unknowns etc. It is my hope that you find this instructor manual concise, to the point, and above all, useful. If I have been remiss in including anything that you feel would help, please let me know. If you need any further assistance or have suggestions or comments regarding the use of the manual, the performance of the experiments, or the use of the keys please do not hesitate to contact me. Stephanie R. Dillon Coordinator General Chemistry Laboratories Florida State University sdillon@chem.fsu.edu
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Table of Contents To The Instructor 0)
Part A. Measurement and Expression of Experimental Data Part B. Graphing and Statistical Analysis A math review, including practice with significant figures, rounding rules, graphing techniques, and statistical analysis.
1)
Conservation of Matter A reaction of copper nitrate and zinc is observed to determine if mass is conserved.
2)
Atomic Spectra Several unknown light sources are identified by use of spectrometry.
3)
Halogen Reactions Hexane and water are used to determine the solubility of the halogens and halides.
4)
Paper Chromatography: An M&M’s® True Colors Paper chromatography is used to analyze the food colorings used in M&M’s candy shells.
5)
Molecular Models Lewis structures are presented in model form and investigated.
6)
Limiting and Excess Reagents Copper nitrate and potassium iodide are reacted at different concentrations to determine which is the limiting reagent and which is in excess.
7)
Redox Reactions in Voltaic Cells: Construction of a Potential Series Micro-scale unit cells of several metals are created and their potentials are measured in order to create a potential series.
8)
Reactions in Aqueous Solutions: Strong Acids and Bases The pH and concentration relationships for the reaction of HCl and NaOH are investigated.
9)
Calorimetry & Hess’s Law The enthalpies of reaction are determined for both magnesium metal and magnesium oxide in water. These enthalpies are then used in conjuction with Hess's Law to determine the enthalpy of reaction for magnesium burning in oxygen. .
10)
Gas Laws and Air Bags Ideal gas law and stoichiometry are used to construct a working mock-up of an automobile airbag.
11)
Intermolecular Forces and the Triple Point of CO2 Intermolecular forces are investigated by observing the temperature depression created when different solvents evaporate. The triple point of CO2 is observed and measured.
12)
The Purification of Water Fresh water samples are tested for phosphate before and after purification.
13)
Kinetics: The Iodine Clock The Iodine Clock Reaction is measured at room, high, and low temperatures, and its rate constant is determined.
14)
Photometric Determination of an Equilibrium Constant The equilibrium constant for the reaction of iron(III) thiocyanate is determined by photometric methods.
15)
Titration of 7-Up® Monoprotic and polyprotic acids are titrated using NaOH.
16)
Hydrogen Phosphate Buffer Systems Students create and then test the buffering capacity of a hydrogen phosphate buffer.
17)
Entropy, Free Energy, and Chemical Equilibrium The thermodynamics of the solubility of Ca(OH)2 are determined using titration.
18)
Electrochemistry: The Nernst Equation Unit cells are built from various metals and then tested at several temperatures. The free energy is determined using the Nernst equation.
19)
Analysis of a Hydrate The formula and percentage of water is determined in an unknown hydrate.
20)
Qualitative Analysis: Cations, Anions, and Complex Ions A single-day, microscale qualitative analysis is used to determine the cations and anions in an unknown mixture.
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21)
Isomerism in Coordination Chemistry A study of the three-dimensional structures of octahedral complexes is performed.
22)
Light Emitting Diode Students will identify the components of a complex ion and predict if that complex ion has a large or small crystal-field splitting energy while constructing an organic diode.
23)
Amino Acid Analysis by Ninhydrin Students identify the amino acids in an unknown mixture using a combination of ninhydrin and TLC.
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Experiment 1: Measurement and Expression of the Experimental Data Instructor Notes and Lab Preparation: Each Fall and Spring semester at Florida State University starts one week before a national holiday, Veterans Day and Martin Luther King Day, respectively. This means that we manage to check in the labs, but then have an off week before the students are able to start performing experiments. Rather than allow the students to waste a full week of lab time, I always assign the following math and graphing review as the first experiment of the semester. Part A is designed for the first semester, and Part B is designed for the second semester of general chemistry. As the check in process is generally a short one, I have each of my teaching assistants give a short lecture on the math involved at the end of the check in day.
Particular points to stress: Scientific or exponential notation is used so often in scientific literature and calculation that I think we often forget how confusing it can be to someone dealing with it for the first time. I always stress that students should look at the values they calculate to make sure they make sense. For example, one of the most common mistakes a student will make when dealing with exponents is when they must change an exponent in order to add or subtract two exponential values. The process requires the student to “move the decimal” in the correct direction to “match up” the exponents. The most common mistake is the movement of the decimal in the wrong direction, so ask the students to check and make sure that the number resulting after the move still makes sense, (i.e., has the same value it did before the move). Simply plugging it into a calculator should do the trick. Another sticky point with my students is an overall lack of graphing skills. I have placed a brief Excel® tutorial at the end of the manual to encourage students to use this program, or one similar to it to complete the graphing exercises. If you choose to have your students complete the graphs by hand, I understand the reasoning, but I would encourage you to consider asking for the graphs in both styles. The reality of the world today is that computers are everywhere. Skillful use of technical programs like Excel is a must for scientific analysis. The most common mistakes that should be discussed with respect to graphing are 1) attempts to fit straight lines to data that does not fit y = mx + b; and 2) irregular spacing of values on the axis. I often see graphs whose axes are marked at regular intervals with the values given as part of the problem. Markings of this sort always generate perfectly straight lines, which thrill the students, but give me migraines. Last but not least, I have found that our discussion of logarithms and the proper use of significant figures in logarithms is generally the first exposure the students will have to the subject. Special attention should be paid to the introduction of this material. .
Lab Report Key Exercises 1A Key 1. For each of the following numbers: a) Indicate the number of significant figures in the number; b) Round the number to 2 significant figures; and c) Place the number into scientific notation: 3.0 x 10-3 a. 0.0030405 1.2 x 106 b. 1,237,888 1.0 x 10-1 c. 0.10101 1.5 x 101 d. 15.0005 e. 0.000009995 1.0 x 10-6 2. Complete the following calculations using the correct number of significant figures and order of operations: o a. Convert 432 K to oF. 318 F %T b. Convert 1.67 %T to Absorbance (A) using A log • A = 1.77 100 P HVap 1 1 c. Solve for P2 using ln 1 , where P1 = 1.5 atm, T1 = 273K, T2 R T2 T1 P2 = 400K, HVap = 40.7 kJ/mol, and R = 8.3145 J/mol • K P2= 445 atm d. Calculate the total mass in grams for: 4.445 x 10-3 g + 15.3 mg + 9.77561 x 10-2 mg = 19.8 mg e. Calculate the total pressure in kPa for: 2.34 atm + 788 Torr – 650 mmHg = 256 kPa 3. Calculate the average and standard deviation for the following set of calibration data: 66.788, 66.898, 66.999, 65.998, 65.778, 67.434, 67.311, 66.009
Average = 66.652
Standard Deviation = 0.638
4. The table of data below was collected using a helium lamp to calibrate a spectroscope used in this general chemistry lab. Use the data to create a calibration graph and then use the graph to calibrate the experimental data collected for other light sources: Color
Wavelength (nm)
Violet Blue Green
388.9 468.6 501.6 .
Spectroscope Reading (AU) 3.78 4.75 4.93