General Chemistry II Excel Graphing Activity

Microsoft Excel: Create a Basic Spreadsheet
To complete this assignment, you will need the Microsoft Excel program installed on
your tablet or computer. Alternatively, you may utilize any of the computer labs on
campus. More information about the UNLV computer labs and locations can be found at
http://oit.unlv.edu/labs-classrooms/computer-labs. Make sure you show all your work
and include all the graphs in each problem in your lab report in order to receive full
credit.
Please read through the following questions and provide the information requested:

1. A general chemistry student tracks her hours of sleep during the course of a
   particularly rough semester and finds the following data:
   Time (months) Average amount of nightly sleep (hours)
   1 9.43
   2 7.38
   3 6.29
   4 4.65
   • Enter the data into cells in an Excel spreadsheet
   • Graph the above data using a scatterplot
   o The month values should appear on the x axis and the hours of sleep
   values should appear on the y axis.
   • Label your axes
   o Include the provided variables and units
   • Title your graph with the following: “Sleep Study”
   • Create a linear trendline on the graph
   • Display the equation and R2 value on the chart
   • Determine if the correlation is strong based upon the calculated R2 value.
   o Any value above 0.90 is considered a strong correlation. The slope of
   the line indicates a positive or negative correlation.
   • Print this graph along with the excel data on one page of paper to turn in.
   Answer the following questions:
   1a) What is the calculated R2 value from the chart?
   1b) Based upon this value, how would you describe the relationship between the length
   of the semester and the amount of sleep the student is getting on average? Is there a
   strong correlation between them? Is this a positive or negative correlation?
   1c) If the semester continued another month (Time = 5), what would the expected amount
   of sleep be? (Hint: use the equation provided by the chart software to calculate the
   amount of sleep). Does your final answer make sense based upon the trend you see in the
   data over time?
   CHE122L: General Chemistry II Excel Graphing Activity
2. A student is titrating a sample in 1.00 mL aliquots over 1.00 minute intervals for a total
   of ten readings. The titrated sample is placed in a spectrophotometer at each interval and
   an absorbance reading is taken. The data is as follows:
   Time (minutes) Absorbance
   1.0 0.98
   2.0 0.86
   3.0 0.77
   4.0 0.65
   5.0 0.55
   6.0 0.46
   7.0 0.35
   8.0 0.22
   9.0 0.19
   10.0 0.17
   • Enter the data above into cells in an Excel spreadsheet
   • In the column to the right of Absorbance, calculate the log of Absorbance
   o You should have three columns total
   o Label your new column “log(Abs)”
   • Graph the time versus log(Abs)
   o The time values should appear on the x axis and log(Abs) values should
   appear on the y axis.
   • Label your axes
   o Log (Abs) does not have units, so none should be listed
   • Title your graph with the following: “Kinetics of Titration”
   • Create a linear trendline on the graph
   • Display the equation and R2 value on the chart
   • Determine if the correlation is strong based upon the calculated R2 value.
   o Any value above 0.90 is considered a strong correlation. The slope of
   the line indicates a positive or negative correlation.
   • Print this graph along with the excel data on one page of paper to turn in.
   Answer the following questions:
   2a) What is the calculated R2 value from the chart?
   2b) Based upon this value, is there a strong correlation between time and the
   log(Absorbance) values? Is this a positive or negative correlation?
   CHE122L: General Chemistry II Excel Graphing Activity
3. A student obtains the following data while preforming an experiment:
   Concentration (mol/L) Signal (counts)
   1.00 0.009
   2.00 0.021
   5.00 0.046
   10.00 0.095
   20.00 0.213
   • Graph the data above:
   o Hint: Use the directions and structure from problem 1 to guide you
   through this exercise.
   Answer the following questions:
   3a) What is the nature of the relationship between concentration and signal?
   3b) What is the concentration of a solution with a signal of 0.065?
4. Dimethyl ether, CH3OCH3, decomposes at high temperatures as shown in the
   following equation:
   CH3OCH3(g) ® CH4(g) + H2(g) + CO(g)
   The following data were obtained when the partial pressure of CH3OCH3 was studied as
   this compound decomposed at 500°C. Use these data to determine the order of this
   reaction. You must show ALL work to get full points (all graphs).
   PCH3OCH3
   (mm Hg)
   312 278 251 227 157
   Time (s) 0 390 777 1195 3155