Go to the tutorial on creating regression lines to find out how to use a regression line with this scatter plot to calculate the concentrations of the two unknowns. Questions are typically answered within 1 hour.*. the help file to find it. To add lines to the scatter plot (Figure 9): This smooth, connected curve helps locate where the steep part of the curve passes through pH 7. off! That is, the closer the line passes through all of the points. We need to calculate the absorbance of each calibration sample, since
image to download Excel file). 'B12' in the equation represents y (the absorbance of the unknown). The measured transmittance was 35.6%. With this approach, the curve is guaranteed to go through all of the data points. Using a new sheet in the spreadsheet workbook, enter your titration data as shown in Figure 6. 258 0 obj
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o��!���-r��S78�f���F�1p�cħ�i. X-block cells. what Excel calls absolute cell addresses) rather than variable
line, we can actually calculate the values of that line for each solution
For example, y = 3x + 4. You will use Beer's law. H�b```a``ee`e`��c`@ �(G���e��W�$�_e�wW�Nӝ`Xw/G�QTN��rD�H����MI4�*�|�u���V�#�L� a. But when making a calibration graph you are looking at the absorbance based on concentration. What would be the concentration of a solution made by diluting 45.0 mL of 4.2 M KOH to 250 mL? respectively. Entering and Formatting the Data in Excel, Creating a Scatter Plot of Titration Data, Repeat for the absorbance data column (B4 through B9 for the sample data), setting the decimal places to, Highlight the concentration data and choose, Highlight the data in both the concentration and absorbance columns (but not the unknown data or the labels for each column), Click on the Title to edit &/or format the entry, Your data should look as though it falls along a linear path, Horizontal reference lines were automatically placed in your chart. The linear trendline should automatically be selected - see below: Choose Display equation on chart option as well (Figure 2): Click OK to close the dialogue. Two properties of spreadsheets result in a huge time-savings when doing
The graph should plot concentration (independent variable) on the x-axis and absorption (dependent variable) on the y axis. Now that we know the intercept and slope of the least-squares best-fit
We have a value for y (Absorbance) and need to solve for x (Concentration). a) 7.5×10−2 M in HNO3 and 0.175 M in HC7H5O2 Q: If 50.0g of CH3OH (MM = 32.04 g/mol) are dissolved in 500.0 mL of solution, what is the concentratio... A: Given,Mass of CH3OH = 50.0 gMolar mass of CH3OH = 32.04 g/molVolume of solution = 500.0 mL = 0.5 L ... Q: Draw two resonance structures for each species − one that obeys the octet rule, and one in which the... A: The given species obeys the octet rule and the formal charge on central atom is one.The outer shell ... Q: Find the pH of each mixture of acids. so that the cells that refer to the intercept and slope are fixed (ie,
2. You want to construct a log-dose-response curve. How well this equation describes the data (the 'fit'), is expressed as a correlation coefficient, R^2 (R-squared). First, a series of solutions of known concentration are tested for their absorption level. Each function accepts
This too can be calculated and displayed in the graph. 0000063825 00000 n
A few items of note: With your graph highlighted, you can click and drag the chart to a wherever you would like it located on the spreadsheet page. And it is just as fast with 100
Make a table of your Absorbance vs. Wavelength data collected on the 5.0 µ g/mL standard solution. The closer R^2 is to 1.0, the better the fit of the regression line.