Expert answer:lab report

Solved by verified expert:3-4 pages lab report attached you will find the result here is the format Purpose: Write one or two complete sentences that describe the objectives, or the reasons, forcompleting the labBackground Information: Present at least a paragraph of information that demonstrates your understanding of the chemistry concepts pertaining to this lab.List of Materials: Include a list of materials needed to complete the experiment.Procedure: If you are expected to design your own procedure, you must write the directions for the lab in a numbered list. Write them in a manner that other chemistry students would be able to follow them. If a numbered procedure is already provided, write a procedure summary in paragraph form.Safety Considerations: List applicable safety rules to consider in this experiment. Include special handling and disposal instructions.Data Table: Include tables with all the information that was recorded throughout the experiment. Tables should be easy to read and include appropriate headings and units.Observations: Record the observations made during the lab.Results: For repetitive problems, provide one sample calculation with appropriate units for each type of calculation. List the results of the calculations with units. In some cases, it may be convenient to record the results as another column on the data table. Percent error should be calculated in this section. For all calculations, the equation must be explained in words first before the numbers are used in an equation. Calculations may be hand written in ink.Graphs: Data should be graphed with maximum use of the paper, labels on both axes with units, a title, and a best-fit line or curve through the data points. Not all activities will require a graph.Questions: Rewrite the analysis/conclusion questions from the lab sheet and then answer each question. Answer all post lab questions.Discussion: State the results of the experiment. Compare the results with standard values (include previously calculated percent error value from the results section) and then state whether the results were too high or too low. Suggest two sources of error related to YOUR data that would have caused these experimental results. Hypothesize why the errors occurred and what might be changed to avoid these errors.Conclusion: Write a five to six sentences that include the following: Restate the original objectives of the lab and explain if they were achieved. Restate the results of the experiment. Describe any additional areas of study that could be done as a result of performing this lab. (i.e. If this lab were done again, what changes would be made? Are there any new questions that were raised by the results of the lab? What should you study next?)
lab_report_11.pdf

lab_report_11_2.pdf

lab_report_11_3.pdf

Unformatted Attachment Preview

© Richard Megna/FUNDAMENTAL PHOTOGRAPHS, NYC
Experiment
11
Periodic Table and
Periodic Law
The halogens are, from left to right, solid iodine crystals, chlorine gas, and
liquid bromine.
Objectives

The following techniques are used in the Experimental Procedure:
Techniques
Similarities between the chemical and physical properties of elements were well
known early in the nineteenth century. Several reports of grouping elements with like
properties provided the background from which the modern periodic table finally
evolved.
However, it was in 1869, nearly simultaneously, when two masterful organizations of all known elements were revealed, one by Dmitri Mendeleev from Russia and
the other from Lothar Meyer from Germany. From their independent research, their
arrangement of the elements established the modern periodic table. Mendeleev showed
that with the elements arranged in order of increasing atomic mass, their chemical properties recur periodically. When Meyer arranged the elements in order of increasing atomic
mass, he found that their physical properties recur periodically. The two tables, however,
were virtually identical. Because he drafted his table earlier in 1869 and because his table
included “blanks” for yet-to-be-discovered elements to fit, Mendeleev is considered the
“father” of the modern periodic table.
In 1913, H. G. J. Moseley’s study of the X-ray spectra of the elements refined
the periodic table to its current status: When the elements are arranged in order of
increasing atomic number, certain chemical and physical properties repeat periodically. See the inside back cover for a modern version of the periodic table. Photos
of most all of the elements can be seen on www.periodictabletable.com.
The periodic table continues to expand with the synthesis of new elements (the
transactinides1), primarily at the Lawrence Livermore National Laboratory (California),
the Joint Institute for Nuclear Research (Dubna, Russia), and the Institute for Heavy-Ion
Introduction
Sovfoto/Universal Images Group/UIG via Getty Images
• To become more familiar with the periodic table
• To observe and to generalize the trends of various atomic properties within groups
and periods of elements
• To observe from experiment the trends of the chemical properties within groups and
periods of elements
Dmitri Mendeleev (1834–1907)
Atomic number: the number of
protons in the nucleus
1
en.wikipedia.org/wiki/Transactinide_element
Experiment 11
149
©Bettmann/Corbis
Research (Darmstadt, Germany). The most recent confirmation (in 2010) is the synthesis of element 117, an element that is one shy of completeing the seventh row of elements in the periodic table. (See Inside back cover.) Glenn T. Seaborg was the most
prominent of the U.S. chemists involved in the synthesis of the transuranium elements.
He was the recipient of the 1951 Nobel Prize in chemistry and was honored with the
naming of element 106, Seaborgium.
In the periodic table, each horizontal row of elements is a period, and each column
is a group (or family). All elements within a group have similar chemical and physical
properties. Common terms associated with various sections of the periodic table are
Michael Watson
Glenn T. Seaborg (1912–1999)
• Representative elements: Group “A” elements
• Transition elements: Groups 3–12
• Inner-transition elements: the lanthanide (atomic numbers 58–71) and actinide
(atomic numbers 90–103) series
• Metallic elements: elements to the left of the “stairstep line” that runs diagonally from B to At
• Nonmetallic elements: elements to the right of the “stairstep line”
• Metalloids: elements that lie adjacent to the “stairstep line,” excluding Al
• Post-transition metals (or Poor metals): metals to the right of the transition metals
• Alkali metals: Group IA elements
• Alkaline earth metals: Group IIA elements
• Chalcogens: Group VIA elements
• Halogens: Group VIIA elements
• Noble gases: Group VIIIA elements
• Rare earth metals: the lanthanide series of elements
• Coinage metals: Cu, Ag, Au
• Noble metals: Ru, Os, Rh, Ir, Pd, Pt, Ag, Au, Hg
The periodicity of a physical property for a series of elements can be shown by
plotting the experimental value of the property versus increasing atomic number. Physical properties studied in this experiment are the following.
Sodium metal is a shiny, but very
reactive metal, typical of Group
1A elements.
Atomic number
17
Molar mass
35.453 g/mol
Density at 293 K
3.214 g/L
Molar volume
22.7 cm3/mol
Melting point
172.22 K
Boiling point
239.2 K
Heat of fusion
3.203 kJ/mol
Heat of vaporization
10.20 kJ/mol
First ionization energy
1251.1 kJ/mol
Second ionization energy 2297.3 kJ/mol
Third ionization energy 3821.8 kJ/mol
Electronegativity
3.16
Electron affinity
349 kJ/mol
Specific heat
0.48 J/g•K
Heat of atomization 121 kJ/mol atoms
Atomic radius
100 pm
Ionic radius (– 1 ion)
167 pm
Thermal conductivity
0.01 J/m•s•K
150
For a very complete look at the properties and periodic trends of the elements, go
to www.webelements.com.
Other physical properties that show trends in groups and periods of elements are
listed for chlorine in the table.
Trends in the chemical properties of the boldface representative elements are studied in this experiment.
Period
Properties of Chlorine
• Ionization energy (Figure 11.1): the energy required to remove an electron
from a gaseous atom
• Atomic radius (Figure 11.2): the radius of an atom of the element
• Electron affinity (Figure 11.3): the energy released when a neutral gaseous
atom accepts an electron
• Density (Figure 11.4): the mass of a substance per unit volume
In this experiment, the relative acidic and/or basic strength of the hydroxides or
oxides in the third period of the periodic table, the relative chemical reactivity of the
halogens, and the relative solubility of the hydroxides and sulfates of magnesium, calcium, and strontium are observed through a series of qualitative tests. Observe closely
the results of each test before generalizing your information.2
2
For trends in chemical properties, go to http://en.wikipedia.org/wiki/category:chemistry
Periodic Table and Periodic Law
(kJ/mol)
He
Cs
Ne
K
Rb
Na
Ar
Kr
Li
Xe
Figure 11.1 Ionization energies (kJ/mol) plotted
against atomic number
Figure 11.2 Atomic radii (pm) plotted against
atomic number
Cl
I
Figure 11.3 Electron affinities (kJ/mol) plotted against
atomic number, defined here as energy released
(kg/cm 3)
Br
(kJ/mol)
F
Figure 11.4 Density (kg/m3) plotted against
atomic number
Procedure Overview: General trends in the physical properties of the elements are
observed and studied in Figures 11.1–11.4. Experimental observations of the physical
and chemical properties of a number of representative elements are made. Special
attention is paid to the chemical properties of the halogens.
Ask your instructor about the working relationship, individuals or partners, for
Part A. For Parts B, C, and D, perform the experiment with a partner. At each circled
superscript 1–18 in the procedure, stop and record your observation on the Report Sheet.
Discuss your observations with your lab partner and your instructor.
Experimental
Procedure
Figures 11.1 through 11.4 plot the experimental data of four physical properties of the
elements as a function of their atomic number. While actual values cannot be readily
obtained from the graphical data, the periodic trends are easily seen. All values
requested for the analyses of the graphical data need only be given as your “best possible” estimates from the figure.
The periodic trends for the elements are analyzed through a series of questions on
the Report Sheet.
A. Periodic Trends in
Physical Properties (Dry
Lab)
Prepare a hot water bath for Part B.3.
B. The Appearance
of Some
Representative
Elements
1. Samples of elements. Samples of the third period representative elements sodium,
magnesium, aluminum, silicon, and sulfur are on the reagent table. Note that the
Na metal is stored under a nonaqueous liquid to prevent rapid air oxidation. Polish
Experiment 11
151
the Mg and Al metal strips with steel wool for better viewing. Record your observations on the Report Sheet.
Since some chlorine, bromine, and iodine vapors may escape the test tubes in
Parts B.2–4 and C.1–3, you may want to conduct the experiments in the fume
hood. Consult with your laboratory instructor.
2. Chlorine. In a clean, 150-mm test tube, place 2 mL of a 5% sodium hypochlorite,
NaClO, solution (commercial laundry bleach) and 10 drops of cyclohexane. Agitate the mixture (Figure 11.5). Which layer is the cyclohexane layer?3
Add ~10 drops of 6 M HCl. (Caution: 6 M HCl is very corrosive. Wash
immediately from the skin.) Swirl or agitate the mixture (with a stirring rod) so
that the HCl mixes with the NaClO solution. Note the color of the chlorine in the
cyclohexane layer. Record your observation. 1 Do not discard—save for Part C.1.
3. Bromine. In a second, clean test tube, place 2 mL of 3 M KBr solution and
3 drops of cyclohexane. Add 5–10 drops of 8 M HNO3. (Caution: HNO3 attacks
skin tissue; flush the affected area immediately with water.) Agitate or swirl the
mixture so that the 8 M HNO3 mixes with the KBr solution. Place the test tube in a
hot water bath to increase the reaction rate. Note the color of the bromine in the
cyclohexane layer. Record, 2 but do not discard—save for Part C.2.
4. Iodine. Repeat Part B.3 in a third test tube, substituting 3 M KI for 3 M KBr.
Record. Compare the appearance of the three halogens dissolved in the cyclohexane. 3 Save for Part C.3.
Figure 11.5 Shake the contents
of the test tube with the little finger.
C. The Chemical Properties
of the Halogens
For Parts C.1–3, six clean, small (~75-mm), test tubes4 are required. Summarize your
observations at the conclusion of Part C.3 on the Report Sheet. Number each test tube
(Figure 11.6). Place the test tubes into a test tube rack.
1. Chlorine and its reactions with bromide and iodide ions. Clean two small test
tubes; add a pinch (on the end of a spatula) of solid KBr to the first test tube and a
pinch of KI to the second. Use a dropping pipet to withdraw the chlorine/cyclohexane layer from Part B.2 and add an (approximately) equal portion to the two
test tubes. Swirl or agitate the solution, observe, and record. Write appropriate net
ionic equations. 4
2. Bromine and its reactions with chloride and iodide ions. Add a pinch of solid
NaCl to a third, small clean test tube and a pinch of KI to the fourth test tube. Use
a dropping pipet to withdraw the bromine/cyclohexane layer from Part B.3 and
add an (approximately) equal portion to the two test tubes. Swirl or agitate the
solution, observe, and record. Write appropriate net ionic equations. 5
Pinch: a solid mass about the size of
a grain of rice
3. Iodine and its reactions with chloride and bromide ions. Add a pinch of solid
NaCl to a fifth, small clean test tube and a pinch of KBr to the sixth test tube. Use
a dropping pipet to withdraw the iodine/cyclohexane layer from Part B.4 and add
an (approximately) equal portion to the two test tubes. Swirl or agitate the solution, observe, and record. Write appropriate net ionic equations. 6
What can you conclude about the relative chemical reactivity of the halogens?
Courtesy of Thermo Fisher Scientific
Figure 11.6 Six labeled test
tubes to test the relative reactivity
of the halogens
Disposal: Dispose of the waste water/halogen mixtures in the Waste Halogens
container.
3
Mineral oil, or any colorless cooking oil, may be substituted for cyclohexane.
A 24-well plate may be substituted for the small test tubes.
4
152
Periodic Table and Periodic Law
Twelve clean, small (~75-mm) test tubes5 are required for the chemical reactions
observed in Part D. Number each test tube (Figure 11.7). Place the test tubes into the
test tube rack.
D. The Chemical Properties
of the Halides
1. The reactions of the halides with various metal ions. Label 12 clean, small test
tubes and transfer the following to each:
•
•
•
•
Test tubes 1, 2, and 3: a pinch of NaF and 10 drops of water
Test tubes 4, 5, and 6: a pinch of NaCl and 10 drops of water
Test tubes 7, 8, and 9: a pinch of KBr and 10 drops of water
Test tubes 10, 11, and 12: a pinch of KI and 10 drops of water
a. Slowly add 10 drops of 2 M Ca(NO3)2 to test
tubes 1, 4, 7, and 10. Observe closely and over
a period of time. Vary the color of the background
of the test tubes for observation. 7
b. Slowly add 10 drops of 0.1 M AgNO3 to test tubes
2, 5, 8, and 11. Observe. After about 1 minute, add
10 drops of 3 M NH3. 8
c. Add 1 drop of 6 M HNO3 (Caution!) and slowly
add 10 drops of 0.1 M Fe(NO3)3 to test tubes
3, 6, 9, and 12. Observe closely and over a
period of time. 9
Appendix G
d. Summarize your observations of the chemical
activity for the halides with the Ca2+, Ag+,
and Fe3+ ions on the grid on the Report Sheet.
Figure 11.7 Twelve labeled test tubes to test the
reactivity of the halides.
Disposal: Dispose of the waste water/halogen mixtures in the Waste Halogens
container.
CLEANUP: Rinse the test tubes with copious amounts of tap water and twice with
deionized water. Discard the rinses in the sink.
1. Sodium.6 Instructor Demonstration Only. Wrap a pea-sized piece of sodium metal
in aluminum foil. Fill a 200-mm Pyrex test tube with water, add 2 drops of phenolphthalein,7 and invert the test tube in a beaker of water (Figure 11.8, page 154).
Set the beaker and test tube behind a safety shield. Punch 5–10 holes with a pin in
the aluminum foil.
With a pair of tongs or tweezers, place the wrapped sodium metal in the mouth
of the test tube, keeping it under water. What is the evolved gas? Test the gas by
holding the mouth of the inverted test tube over a Bunsen flame. 10 A loud pop indicates the presence of hydrogen gas. Account for the appearance of the color change
in the solution. 11
E. Chemical
Reactivity of Some
Representative
Elements
5
A 24-well plate may be substituted for the small test tubes.
Calcium metal can be substituted for sodium metal with the same results.
7
Phenolphthalein is an acid–base indicator; it is colorless in an acidic solution but pink in a basic
solution.
6
Experiment 11
153
200-mm
test tube
Jo A. Beran/Trey Hernandez
Phenolphthalein
600-mL
beaker
Sodium metal
wrapped in
aluminium foil
Figure 11.8
Collection of
hydrogen gas from
the reaction of
sodium and water
2. Magnesium and aluminum.
a. Reaction with acid. Polish 5-cm strips of Mg and Al metal; cut 5-mm pieces and
place them into separate small test tubes. Add ~10 drops of 3 M HCl to each test
tube. (Caution: Do not allow the HCl to touch the skin. Wash the affected area
immediately.) Which metal reacts more rapidly? 12 What is the gas that is
evolved? 13
b. Reaction with base. Add (and count) drops of 6 M NaOH to each test tube until
a precipitate appears. Continue to add NaOH to the test tube containing the aluminum ion until a change in appearance occurs. Add the same number of drops
to the test tube containing the magnesium ion. Record your observations.8 14
Add drops of 6 M HCl until both solutions are again colorless. Observe
closely as each drop is added. Record and explain.
3. Solubilities of alkaline-earth cations.
a. Solubility of the hydroxides. Place 10 drops of 0.1 M MgCl2, 0.1 M CaCl2, and
0.1 M Sr(NO3)2 in three separate, clean test tubes. Count and add drops of
0.050 M NaOH until a cloudiness appears in each test tube. Predict the trend in
the solubility of the hydroxides of the Group 2A cations. 15
b. Solubility of the sulfates. Place 10 drops of 0.1 M MgCl2, 0.1 M CaCl2, and
0.1 M Sr(NO3)2 in three separate, clean test tubes. Count and add drops of
0.10 M Na2SO4 until a cloudiness appears in each test tube. Predict the trend in
the solubility of the sulfates of the Group 2A cations. 16
4. Sulfurous acid and sulfuric acid. Because of the possible evolution of a foulsmelling gas, you may want to conduct this part of the experiment in the fume
hood. Consult with your instructor.
a. Place a double pinch of solid sodium sulfite, Na2SO3, into a clean small or
medium-sized test tube. Add 5–10 drops of 6 M HCl. Test the evolved gas with
wet blue litmus paper. Write a balanced equation for the reaction.17
b. Repeat the test, substituting solid sodium sulfate, Na2SO4, for the Na2SO3.
Account for any differences or similarities in your observations.18
Disposal: Discard the solutions as directed by your instructor.
CLEANUP: Rinse the test tubes twice with tap water and with deionized water. Discard the rinses in the sink.
The Next Step
The periodic trends for many chemical and physical properties of the elements can be
found on the Internet. There are many Web sites, and the data are plotted for many
properties using various coordinates. A first reference is www.acs.org. Seek a data
plot, for example, of atomic radii versus ionization energy or for any properties as
listed in the table for chlorine in the Introduction.
8
Magnesium ion precipitates as magnesium hydroxide, Mg(OH)2; aluminum ion also precipitates as
–
the hydroxide, Al(OH)3 but redissolves in an excess of OH to produce Al(OH)4 –, the aluminate ion.
154
Periodic Table and Periodic Law
Experiment 11 Prelaboratory Assignment
Periodic Table and Periodic Law
Date __________ Lab Sec. ______ Name ____________________________________________ Desk No. __________
1. On the blank periodic table, clearly indicate six of the following element sections, using your own color code.
a. Representative elements
h. Alkali metals
b. Transition elements
i. Alkaline earth metals
c. Inner-transition elements
j. Halogens
d. Chalcogens
k. Noble gases
e. Coinage metals
l. Noble metals
f. Metalloids
m. Lanthanide series
g. Post-transition metals
n. Actinide series
Periodic Table
2. Sketch in the stairstep line that separates the metals from the nonmetals on the periodic table.
3. Identify the atomic numbers of the elements that would be called the transactinide elements.
Experiment 11
155
4. Classify each of the following elements according to the categories of elements identified in question 1:
a. Magnesium _______________
f. Potassium
b. Plutonium
_______________
g. Element 118 _______________
c. Argon
_______________
h. Silver
_______________
d. Zirconium _______________
i. Lead
_______________
e. Bromine
j. Titanium
_______________
_______________
_______________
5. Refer to Figure 11.1. Which of the following has the highest ionization energy?
a. carbon or oxygen
______________________
c. magnesium or aluminum
______________________
b. phosphorus or sulfur
______________________
d. magnesium or calcium
______________________
6. Refer to Figure 11.2. Which of the following has the largest atomic radius?
a. carbon or oxygen
______________________
c. magnesium or aluminum
______________________
b. phosphorus or sulfur
______________________
d. magnesium or calcium
______________________
Compare your answers for questions 5 and 6. What correlation can be made?
7. a. Proceeding from left to right across a period of the periodic table, the elements become (more, less) metallic.
b. Proceeding from top to bottom in a group of the periodic table, the elements become (more, less) metallic.
8. Consider the generic equation for the reaction of the halogens, X2 and Y2:
X2(g) + 2Y–(aq) —› 2X–(aq) + Y2(g)
Is X2 or Y2 the more reactive halogen? Explain.
9. a. Experimental Procedure, Part B.2. What commercially available compound is used to generate Cl2 in the
experiment?
b. Experimental Procedure, Part B. The observation for the presence of the elemental form of the halogens is in a solvent other than water. Identify the solvent.
c. Experimental Procedure, Part E.3. Identify the tests used to observe the periodic trends in the chemical proper …
Purchase answer to see full
attachment

How it works

1. Paste your instructions in the instructions box. You can also attach an instructions file
2. Select the writer category, deadline, education level and review the instructions 
3. Make a payment for the order to be assignment to a writer
4.  Download the paper after the writer uploads it 

Will the writer plagiarize my essay?

You will get a plagiarism-free paper and you can get an originality report upon request.

Is this service safe?

All the personal information is confidential and we have 100% safe payment methods. We also guarantee good grades