In: Chemistry

how to calculate the equilibrium concentration using absorption data and the best fit line from the beer's law

Using Beer’s Law To Find An Equilibrium Constant For Iron(III) Thiocyanato Ion Introduction For the reaction aA+ b B cC+ d D it has been shown in class that Keq = [C]c [D]d [A]a [B]b where Keq is the equilibrium constant for the reaction. The value of the equilibrium constant may be calculated from experimental data if the concentrations of both the reactants and products at equilibrium are known. Additionally, all equilibrium concentrations can be calculated if a single equilibrium concentration is known along with all other “initial” concentrations are known. The student will use spectrophotometry and Beer’s Law to determine this single equilibrium concentration. The equilibrium reaction studied in this experiment is formation of the iron(III) thiocyanato complex [Fe(SCN)+2] from the iron and thiocyanate ions: Fe+3 + SCN- Fe(SCN)+2 with the corresponding equilibrium expression: Keq = [Fe(SCN)+2] [Fe+3][SCN- ] The thiocyanate ion is colorless, the iron cation is slightly yellowish, but the iron(III) thiocyanato complex is a deep red-orange. Remember that many colored species will follow Beer's law: A = abc where A is the absorbance measured by a spectrophotometer, a is the absorptivity at a given wavelength of light, b is the path length and c is the concentration of the absorbing species. Since the wavelength and path length will be held constant, the relationship between absorbance and concentration should be linear.

C
D
3
2
6
7
8
5
9
4
1
0
3
4
Plot the data and line of best fit in R and paste it into this document
Code:
Plot:

collect data exhibiting a relatively linear trend, find the line of
best fit, plot the data and the line, interpret the slope, and use
the linear equation to make a prediction. Also find r2 (coefficient
of determination) and r (correlation coefficient). Discuss your
findings. Your topic may be that is related to sports, your work, a
hobby, or something you find interesting.

Using the aqueous equilibrium constants, calculate the
concentration of OH- in M and pH for the following solutions (given
that all are at 25 degrees celsius):
0.15 M NaBrO
8.2×10−2 M NaHS.
A mixture that is 0.13 M in NaNO2 and 0.25 M in Ca(NO2)2.
Thank you! :)

Create a calibration curve and line of best fit using this
information and Beer's Law
Volume of Stock Solution (ml)
Concentration
Absorbence
1.00
2.066
0.121
2.00
1.969
0.254
5.00
1.981
0.631
7.00
2.044
0.856

Find the line y = b + mx of best fit through the data {(.1,
.2),(.2, .3),(.3, .7),(.5, .2),(.75, .8)}, using the least squares
criterion.
(Use one of the software tools: Excel, SPSS, Mathematica, or
MATLAB to answer the following items, and print out your results
directly from the software)

Movies
3
6
0
9
14
5
7
12
2
1
7
0
5
11
4
Books
7
0
18
0
1
4
5
0
6
2
10
9
2
2
0
Find the line of best fit.
r =
What is the SSE for this problem?

*Please provide r studio code/file*
1) Find the equation of the best fit line using least
squares
linear fit of x,y:
set.seed(88)
x <- 1:100
y <- jitter(1.5*x+8,amount=10)
2) For question 1, Draw the P=0.95 prediction intervals for y
when x=1:150
3) For question 1, Find the equation of the best fit line
using
median-based linear fit of x,y.
4) For question 3, draw the P=0.95 prediction interval for y
# when x=1:150

Using the GDP Data do the following:
Generate the best fit model (regression)
Generate the specific regression form
Explain any dummy variables created
Explain any time variables created
Discuss the significance of all variables
Generate and discuss the residual plot
GDP
C
I
G
822.2
625.7
93.6
110.1
751.5
592.3
62.5
121.3
703.6
574.3
39.2
126.6
611.8
523.0
11.8
122.4
603.3
511.0
17.5
118.0
668.3
546.9
31.6
133.0
728.3
580.6
58.4
137.0
822.5
639.6
74.9
158.9
865.8
663.5
93.6
153.2...

If the line of best fit for your torque speed curve is described
by the following equation, calculate the no-load speed of the
motor. T= -0.021x+0.32

Find a study that uses linear regression and a line of best fit.
What is the Correlation Coefficient? What conclusions can you make
about the data? Is there a correlation and how strong is it?

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