CBL v3 INSTRUCTIONS

To access the program

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PROGRAMS CHEMISTRY Graphical Analysis

The program displays three main screen areas: TEXT, TABLE, and GRAPH. Only one of these areas is active at any time, to activate the area Left click on it once. To work in either the data table, the graph, or the text box, the area has to be active. How important is this? if you try to use the ANALYZE menu with while the GRAPH area is gray, you will not be able to use linear regression functions.

Plot for density

To enter the data

  • Select the Table Area by Left clicking on it once.
  • Left click on the first space in the X column and start entering the data. Pressing return will move the cursor over to the Y data, then to the next X, ...

    You will see the graph change automatically as you enter data. You need to enter the data in the order you want. If one point seems too low and the next seems too high, the data points are probably out of place.

    Now that the data has all been entered we have to change the axis labels.

  • Select the Table Area by Left clicking on it once (if it is not already selected).
  • Right click anywhere on the Table Area and select [Column Options]-[Data Set |X] from the drop down menu.

    The window that appears has two tabs:[Column Definition] and [Options]

  • In the [Column Definition] window, enter the name of the measured quantity (volume, time, concentration...).
  • Do the same with the Y column.

    Here you can also enter a short name and unit for the column. The [Options] tab allows you to change number of decimal places and point protector style for the data column. You can also add a title to the table. Just Right click anywhere on the Table Area and select [Data Set Options]-[Data Set #] from the drop down menu.

    Now we need to work on the graph.

  • Select the Graph Area by clicking on it once (if it is not already selected).
  • Right click anywhere on the Graph Area and select [Graph Options] from the drop down menu.
  • Enter a title for your graph.
  • Since we want to draw the best straight line, the [Connect Points] options has to be unchecked.

    The [Axes Options] tab allows you to manipulate the tick and axes labels. For example, if you want the X axis tick labels to be read up-down instead of sideways you can rotate the thick labels by 90 degrees.

    To draw the best straight line,

  • Select the Graph Area by Left clicking on it once (if it is not already selected).
  • In the Menu Bar, Left click on the [Analyze] menu and select [Curve Fit] from the drop down menu.

    Most of our work is with linear graphs. Select [mX + b] for a linear fit. Click on Try Fit then OK. The Y and the X at this point will have been replaced with your units, here you would select [mV+ V]. If the line is not what you wanted, you can remove it by Left clicking on the Floating Box and select [Delete].

    Finishing your work

    Select the Text Area by Left clicking on it once (if it is not already selected). In the Text Area enter your name and any comment you want to include. The saving and print options are listed under the FILE menu. You can print the data alone, the graph alone, or both together. In this class we will need to PRINT WHOLE SCREEN, that way we will get the data, the graph, and the text box.

    Do not print until you are authorized to do so. Your work might not be ready to print and if too many print jobs are sent to the printer at one time, it might get jammed and nobody will be able to print.

    Plot for the Empirical Formula of a Salt

    The Empirical Formula has two X axes:

  • Top X axis = mol of cation
  • Bottom X axis = mol of anion

    But the graphical analysis can only handle one X axis at the time. The top axis has to be drawn by hand after printing.

    Draw the lines

    It is best to put a line at every [# of mol] value. To do that,

  • Right click anywhere on the Graph Area and select [Graph Options] from the drop down menu.
  • In the [Axes Options] tab, check the [Make all Values Major Ticks] option for the X axis.

    The Data is divided in two sets. In the first set, the cation is the limiting reagent. In the second set, the anion is the limiting reagent.

  • Select the first set by highlighting them in the table (hold Left click).
  • In the Menu Bar, Left click on the [Analyze] menu and select [Curve Fit] from the dropdown menu. Select [mX + b] for a linear fit. Click on Try Fit then OK.
  • Do the same for the second set of points.

    You can make the Floating box disappear. Just Right click on it, select [Linear fit Options] from the drop down menu and uncheck the [Show on graph] option.

    The axes automatically adjust to fit the data but if you need more room on either side of the graph you can adjust the lower and upper limits of the axes. To do that,
  • Right click on the anywhere in the Graph Area and select [Graph Options] from the drop down menu.
  • In the [Axes Options] tab, select [Manual] from the [Scaling] dropdown menu.

    Here is what the finished graph looks like. The top axis and labels were inserted into an image file of the graph using MS Paint.

    Plot for an Exothermic Thermograph

    The Exothermic Thermograph has three X regions:

  • Region 1 = Pre Reaction Readings
  • Region 2 = Reaction (Vertical line)
  • Region 3 = Post Reaction Readings

    Plot region 1 of Pre Reaction Readings,

  • Select the first set [T=0 to T=2.0] by highlighting them in the table (hold Left click).
  • In the Menu Bar, Left click on the [Analyze] menu and select [Curve Fit] from the drop down menu. Select [mX + b] for a linear fit. Click on Try Fit then OK.

    Region 2 can be drawn manually or inserted into the data. Here the reaction occurs between 2.0 and 2.5 minutes. Thus we insert the values [t=2.3, T=20] and [t=2.3, T=37]. The temperature T has been chosen to be slightly lower than the lowest data point and slightly higher than the highest data point.

  • Right click anywhere on the Graph Area and select [Graph Options] from the drop down menu. Check the [Connect Points] option (if it is not already checked) so the line in the reaction region [Region 2] will show.
  • For the third set of points, select only the points that seem to follow a trend line. Usually the first 3 or 4 points of region 3 have to be ignored.

    The ΔT value is obtained from the difference between the point where the vertical line at t = 2.3 intersects the line from region 1 (T1) and the point where the vertical line at t = 2.3 intersects the line from region 2 (T2). Just Mouse Over the intersections, the coordinates are displayed on the lower left corner of the graph.