Unformatted text preview: Name:
ID Number: Quiz Section:
Lab Partner: Points assigned to tables, graphs
questions, and calculations. EXPERIMENT 6: ATOMIC EMISSION SPECTROSCOPY(AES)
Part I. Measuring the Hydrogen Emission Spectrum
Part II. An Application of AES; Determination of Sodium Note:
All sections of this
report must be typed Total Points = 60 (5 notebook, 55 template)
By signing below, you certify that you have not falsified data, that you have not plagiarized any part of this lab report, and that
all calculations and responses other than the reporting of raw data are your own independent work. Failure to sign this
declaration will cost you 5 points.
Signature: Part I. Measuring the Hydrogen Emission Spectrum
Use these in the data analysis.
Data here will autofill into the third
column of Tables 24 DATA
Table 1. Hydrogen Emission Data
Spectroscope Data
Color
violet
bluegreen
red Ocean Optics Spectrometer
λ (nm)
(descending order) Wavelength, nm A: Data Analysis
Hypothesis #1: nf (assumed) = 1; therefore ni = 2, 3, 4, 5, 6.
If the hypothesis is correct, a plot of 1/λ vs. 1/ni2 should be linear (good R2 ) and the Rydberg constants
calculated from slope and the yintercepts should be the same. Calculate 1/λ and 1/ni2 , then plot the data
and include the equation and R2 on the plot. Compare the R values calculated from the slope and yint. Table 2. Hypothesis #1; nf = 1; ni = 2, 3, 4, 5, 6
ni values 1/ni2 λ (nm)
0.0
0.0
0.0
0.0
0.0 1/λ nm1 Put your plot of 1/λ vs 1/ni2 here. Make your plot big enough to cover this instruction box so that it is large
enought for someone else to read.
Use the online resources if you need help figuring out how to plot a graph in Excel.
Title the graph and label the X and Y axis, including the correct units. Be sure to double check your units and
formatting once you print the report. Excel Help for Data in Tables 2, 3
&4
1. Column B: =1/(Click on column A
entry)^2, Enter. Copy and paste into
remaining cells.
2. Column D: =1/(Click on Column C
entry), Enter. Copy and paste into
other cells.
3. Format cells to desired number
of decimal places. Highlight cells,
Format, Number, select number of
decimal places. A number that does
not fit the column width will show an
error and a number that is too small
for the formatting will register as
zero. You also have the option to
write the number in scientific
notation.
4.Plot 1/λ on the yaxis and 1/ni2 on
the xaxis. Right click on any data
point and add a trendline. In the
trendline help box, choose linear
type, and under the options tab,
click on the boxes in front of "display
equation on chart" and "display Rsquared on chart". Right click on the
equation, choose "format data
labels" or "format trendline label"
and change the number properties
so that 5 sig figs are displayed.
(Failure to do this on each plot
will cost you a point!)
5. From the Rydberg equation, you
know that the slope is equal to R
and the yintercept is equal to R/nf2.
Calculate R both ways and
compare. Report your results to 4
or 5 sig figs. Add a Trendline to show the linear fit of your data. Choose a linear line and choose the options that will
"display the equation on the chart". Slope:
yintercept: R from slope:
R from yintercept: nm1
nm1 Is nf=1? Hypothesis #2: nf (assumed) = 2; therefore ni = 3, 4, 5, 6, 7.
If the hypothesis is correct, a plot of 1/λ vs. 1/ni2 should be linear (good R2 ) and the Rydberg constants calculated from slope
and the yintercepts should be the same. Calculate 1/λ and 1/ni2 , then plot the data and include the equation and R2 on the plot.
Compare the R values calculated from the slope and yint. Page 1 of 12 Hypothesis #2: nf (assumed) = 2; therefore ni = 3, 4, 5, 6, 7.
If the hypothesis is correct, a plot of 1/λ vs. 1/ni2 should be linear (good R2 ) and the Rydberg constants calculated from slope
and the yintercepts should be the same. Calculate 1/λ and 1/ni2 , then plot the data and include the equation and R2 on the plot.
Compare the R values calculated from the slope and yint.
Table 3. Hypothesis #2; nf = 2; ni = 3, 4, 5, 6, 7 ni values 1/ni2 λ (nm)
0.0
0.0
0.0
0.0
0.0 1/λ nm1 Put your plot of 1/λ vs 1/ni2 here. Make your plot big enough to cover this instruction box so that it is large enought for
someone else to read.
Use the online resources if you need help figuring out how to plot a graph in Excel.
Title the graph and label the X and Y axis, including the correct units. Be sure to double check your units and formatting
once you print the report.
Add a Trendline to show the linear fit of your data. Choose a linear line and choose the options that will "display the
equation on the chart". Slope:
yintercept: R from slope:
R from yintercept: nm1
nm1 Is nf=2? Hypothesis #3: nf (assumed) = 3; therefore ni = 4, 5, 6, 7, 8.
If the hypothesis is correct, a plot of 1/λ vs. 1/ni2 should be linear (good R2 ) and the Rydberg constants calculated from slope and
the yintercepts should be the same. Calculate 1/λ and 1/ni2 , then plot the data and include the equation and R2 on the plot.
Compare the R values calculated from the slope and yint. Table 4. Hypothesis #3; nf = 3; ni = 4, 5, 6, 7, 8
ni values 1/ni2 λ (nm)
0.0
0.0
0.0
0.0
0.0 1/λ nm1 Put your plot of 1/λ vs 1/ni2 here. Make your plot big enough to cover this instruction box so that it is large enought for
someone else to read.
Use the online resources if you need help figuring out how to plot a graph in Excel.
Title the graph and label the X and Y axis, including the correct units. Be sure to double check your units and formatting
once you print the report.
Add a Trendline to show the linear fit of your data. Choose a linear line and choose the options that will "display the
equation on the chart". Slope:
yintercept: R from slope:
R from yintercept: nm1
nm1 Is nf=3? Summary of information to be used in the next section (from the data for the correct nf value above):
R (in SI units)
b (in SI units) m1
m1 B: Ionization Energy and Energy Levels
Enter the values for h and c, then calculate the ionization energy per atom from nf (IE = hc·b),where b is the yintercept in m1. Page 2 of 12 h (Planck's const) c (speed of light) Js Type the calculation of IE per atom from nf IE(per atom) m/s J If nf is not 1, the IE calculated above is not the regular ionization energy.
We need to add an energy term, for the ground state (n =1) to nf transition, to the IE just calculated.
This energy term is equal to 3/4hcR for nf=2 and 8/9 hcR for nf=3.
Calculate IEtotal from ground state (nf = 1), both per atom and per mole: Type the calculation of IEtotal per atom and per mole. IE(per atom) J Avogadro's # mole 1 IE (per mole) J/mole Calculate the allowed energy levels: En(per atom) = hcR/n2 where n= 1, 2, 3, ... (with R in units of m1)
The cells under the h, c, and R headings below will autofill from cells B140, C140, and B133, respectively,
so you just need to enter the formula in Column F to calculate En.
En
n
h
c
R
Eα ∞ 0.000E+00 0.000E+00 E4 4 0.000E+00 0.000E+00 0.000E+00 E3 3 0.000E+00 0.000E+00 0.000E+00 E2 2 0.000E+00 0.000E+00 0.000E+00 E1 1 0.000E+00 0.000E+00 En(J) 0.000E+00 0.000E+00 Part II. An Application of AES; Determination of Sodium
DATA
Molar mass of NaCl
Calculated mass of NaCl needed to make 100 mL of 0.100 M stock solution
Actual mass of NaCl weighed out
Actual molarity of stock NaCl solution prepared g/mole
g
g
M Volume of 0.100 M stock NaCl solution for preparing 100 mL of each standard
Desired
mL of 0. 1M NaCl
Standard
Final [NaCl] (M)
needed
Note:
1
0.0010
For Table 5, calculate the ACTUAL [Na+] (M and mg/8 fl. oz.) of the
2
0
standards based on the mass of NaCl you weighed out. Use the
3
0
conversion factor:
4
0
5
0
8 fl oz. = 0.2366 L to calculate the [Na+] in mg/8 fl.oz.
Table 5: Flame Photometer Data
Sample
[Na+], (M)
Standard 1
Standard 2
Standard 3
Standard 4
Standard 5
Table 5 (continued)
Sample
Gatorade
Coca Cola
Site #1, 8.5 m depth
Site #1, 9.5 m depth
Site #1, 10.5 m depth
Site #1, 11.5 m depth
Seawater [Na+], (mg/8 fl oz) Intensity Dilution Factor
25
2.5
1
2
10
100
400 Intensity
For your convenience, the
depth, dilution factors, and
intensity values for the
freshwater and seawater
samples will autofill in the
tables below. DATA ANALYSIS
Put your plot of Intensity vs. [Na+] (M) here. Make your plot big enough to cover this instruction box so
that it is large enought for someone else to read.
Use the online resources if you need help figuring out how to plot a graph in Excel.
Page 3 of 12
Title the graph and label the X and Y axis, including the correct units. Be sure to double check your
units and formatting once you print the report. You will plot the data and obtain the trendline
equation from the graph. This will be the
calibration equation in the form of y=mx+b and
you will use it, with your intensities (y) from the
data table above, to determine the [Na+] in the
samples. For the drink samples, you will need
to convert the [Na+] from M to mg/8 fl oz. in
order to compare with the manufacturers'
values. Put your plot of Intensity vs. [Na+] (M) here. Make your plot big enough to cover this instruction box so
that it is large enought for someone else to read.
Use the online resources if you need help figuring out how to plot a graph in Excel.
Title the graph and label the X and Y axis, including the correct units. Be sure to double check your
units and formatting once you print the report.
Add a Trendline to show the linear fit of your data. Choose a linear line and choose the options that
will "display the equation on the chart". You will plot the data and obtain the trendline
equation from the graph. This will be the
calibration equation in the form of y=mx+b and
you will use it, with your intensities (y) from the
data table above, to determine the [Na+] in the
samples. For the drink samples, you will need
to convert the [Na+] from M to mg/8 fl oz. in
order to compare with the manufacturers'
values. slope
yintercept M1 Using the calibration equation (eqn of the line), calculate the concentration of sodium in the original samples.
What percent of the labeled value is the measured value?
mg/8 fl. oz, sports drink
mg/8 fl.oz on label
% measured vs labeled values mg/8 fl. oz. for the cola drink
mg/8 fl.oz on label
% measured vs labeled values Helpful Hints: Calculating concentrations from measured atomic emission
intensities
1. y = mx + b, where y = your measured intensity and m and b are the slope and
intercept from your plot, respectively.
2. Solve for 'x', multiply by the appropriate dilution factor from Table 5, and, for the
cola and gatorade samples, convert the answer from M to mg/8 fl oz.
3. Also for the cola and gatorade samples, find the ratio of the measured amount to
the reported amount. In other words, the measured amount is what % of the
maximum amount allowed in the sample as reported on the label? Type the calculation for determining the concentration of Na+ in the original Gatorade sample in units of mg/8 fl.oz. Freshwater samples as a function of depth:
Depth (m)
Intensity
Dilution Factor
8.5
0
1
9.5
0
2
10.5
0
10
11.5
0
100 Concentration (M) Page 4 of 12 Put your plot of concentration (M) vs depth here. Make your plot big enough to cover this instruction box so that it is large enought
for someone else to read.
Use the online resources if you need help figuring out how to plot a graph in Excel. Choose an XY scatter plot with a smooth line
and data markers.
Title the graph and label the X and Y axis, including the correct units. Be sure to double check your units and formatting once you
print the report. At the deepest point, what is the ratio of Seawater to Freshwater? What about the most shallow point?
Seawater Dilution Factor
400 Intensity Concentration (M)
0 Dilution Factor = [Na Seawater]/[Na Freshwater, deepest point or most shallow point]
deepest
most shallow
Type the calculation for determining the concentration of Na+ in the original seawater sample. RESULTS AND DISCUSSION
1. Which of the three hypotheses fits the Rydberg equation? Explain your choice. 2. Based on your data, which ni and nf values are associated with the most intense peak near 650 nm? 3. How well does your ionization energy compare with the literature value of 1.312 x 106 J/mole? Calculate and discuss the % error. 4. The flame photometer uses a natural gas flame (~ 1800 oC). What would happen to the emission intensities if an acetylene  nitrous oxide
flame (~3000 oC) was used instead? Page 5 of 12 5. Assuming your measured Na concentrations are correct, how accurate is the labelling on the drinks? Calculate and discuss the % error. 3. How well does your ionization energy compare with the literature value of 1.312 x 106 J/mole? Calculate and discuss the % error. 4. The flame photometer uses a natural gas flame (~ 1800 oC). What would happen to the emission intensities if an acetylene  nitrous oxide
flame (~3000 oC) was used instead? 5. Assuming your measured Na concentrations are correct, how accurate is the labelling on the drinks? Calculate and discuss the % error. Laboratory Waste Evaluation (1 pt)
Laboratory waste is considered anything generated during an experiment that is disposed of down the sewer drain, thrown in the garbage,
collected in a container for disposal by the UW Environmental Health & Safety department, or released into the environment. Based on the written
lab procedure and your actions during the lab, list the identity and approximate amount (mass or volume) of waste that you generated while
performing this experiment. Page 6 of 12 ned to tables, graphs
ns, and calculations. 5 a in Tables 2, 3
lick on column A
y and paste into
lick on Column C
and paste into
esired number
Highlight cells,
lect number of
umber that does
idth will show an
that is too small
ill register as
the option to
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ick on any data
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choose linear
options tab,
n front of "display
nd "display RRight click on the
ormat data
endline label"
ber properties
displayed.
on each plot
nt!) 1 g equation, you
is equal to R
is equal to R/nf2.
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our results to 4
2 3 Page 7 of 12 1 2 3 1 2 3 1 Page 8 of 12 from nf
2 r mole. 2 2 2 1 1 onvenience, the
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mg/8 fl oz. in
nufacturers' Page 9 of 12 ain the trendline
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t % of the 2 3 1 Page 10 of 12 2 2
3 2 2 2 Page 11 of 12 2 2 1 60 Page 12 of 12 ...
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This note was uploaded on 05/24/2011 for the course CHEM 152 taught by Professor Chiu during the Spring '08 term at University of Washington.
 Spring '08
 Chiu
 Atom, pH

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