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AP Chemistry Lab Manual
Lab Notebook Guidelines 2
QRS lab 5
Qualitative Analysis of the Group III Cations 6
How Much Zinc is in a penny? 11
Predicting Products of Chemical Reactions 12
Redox Titration: The Standardization of Potassium Permanganate 13
The EMF Activity Series 15
Heat of Fusion for Ice 19
Additivity of Heats of Reaction: Hess’s Law 21
Heat of Combustion of a metal-an inquiry based approach 23
VSEPR and Molecular Geometry 25
Formation of a Coordination Complex of Copper (II) 26
Kinetics of a Reaction -- An Iodine Clock 28
Where did the Crystal Violet go? 30
Chemical Equilibrium: Finding a Constant, Keq or Kc 35
Entropy of a Reaction 37
Catalytic Converter—Hot Copper Catalysis 38
Equilibrium and Le Châtelier's Principle 40
Strong Acid Strong Base Titration 43
Titration of a weak acid 45
Determination of the Ka of Weak Acids 46
Determination of the Ksp of an Ionic Compound 49
Buffer Laptop Palooza 51
Preparation and Properties of Buffer Solutions 53
Corrosion Cells 56
Polyatomic Ions 59
Molecular Geometry 60
Rules of Writing Equations 62
AP Chemistry Syllabus 64
Class Rules 66
Description of Content Covered 67
End of Year Review 70
Solution Practice 79
Redox Practice 80
Thermochemistry: Standard Heats of Formation Worksheet 82
Gas laws practice. 83
8 and 9 Practice worksheet 85
Equilibrium and Entropy Practice 89
Ch. 10 questions 92
Chapter 11 Practice 92
Kinetics part I 94
Kinetics part II 97
Accessing Prior Knowledge Acids and Bases 100
pH PRACTICE 101
Ka and Kb practice 102
Titration Curve Practice 103
Chapter 14 and 15 practice: 110
Ksp practice. Keep me but put all answers in your notes. 112
Electrochem practice 114
Lab Notebook Guidelines
You must have a composition notebook or the notebook from Chem I as a lab notebook.
A lab notebook should be used to explain lab procedures, record all lab data, and show how calculations are made. You may also use the notebook to discuss the results of an experiment and to explain the theories involved.
A record of lab work is an important document which will show the quality of the lab work that you have done. You may need to show your notebook and your lab reports to the Chemistry Department at a college or university in order to obtain credit for the lab part of an AP Chemistry class. As you record information in your notebook, keep in mind that someone who is unfamiliar with your work may be using this notebook to evaluate your lab experience in chemistry. When you explain your work, list your data, calculate values and answer questions, be sure that the meaning will be obvious to anyone who reads your notebook.
Guidelines for the notebook:
- Write your name and class on the front cover.
- In black or blue ink, number all the right hand pages on the lower right corner if they are not already numbered.
- Save the first 2 pages for a Table of Contents. This should be kept current as you proceed. Each time you write up a lab, place the title and page numbers where the lab report begins in the Table of Contents.
- Write in ink. Use only the right hand pages.
- If you make a mistake, DO NOT ERASE OR SCRIBBLE. Just draw ONE LINE through your error, and continue. It is expected that some errors will occur. A lab notebook is a working document, not a perfect, error-free, polished product. Errors should be corrected by drawing one line through the mistake, and then proceeding with the new data.
- Do not use the first person or include personal comments.
Prelab Instructions:
1. On most every lab you will have prelab instructions. If it has you read, read carefully as there will often times be a quiz over that content. If there are questions you are supposed to answer, do them on a separate sheet of paper and hand them in as your ticket into lab. If there is a code word in the procedure or weird instructions be prepared to follow them.
2. Some labs will be full write-ups and some will be data and calculations only. You must always answer questions if they are in the lab manual. You must get your data stamped in your lab notebook before you leave the lab.
Lab Reports (Lab reports will be worth 50 points)
Include the following information in your lab reports. Label each section
1. Title – The title should be descriptive. Experiment 5 is not a descriptive title.
2. Date and lab station – This is the date you performed the experiment and lab station.
3. Purpose – A brief statement of what you are attempting to do. Must be a sentence.
4. Procedure – A shortened description of the method you are using. You may refer to the lab manual for specific instructions, but you should include a brief statement of the method. Do not include lengthy, detailed directions. A person who understands chemistry should be able to read this section and know what you are doing.
5. Reactions: Write a balanced reaction including states of matter for any reactions. If there are no reactions omit this section.
6. Data- Record all your data directly into your lab notebook on the right-hand pages. Organize your data in a neat, orderly form. Label all data very clearly. Use correct sig figs and always include proper units. Underline, use capital letters or use any device you choose to help organize this section well. Space things out – don’t try to cram everything on one page. A data table must have a label and a title. e.g. – Table 1: Density Values for Sugar Solutions.
7. Calculations and Graphs- You should show how calculations are carried out. Give the equation used and show how your values are substituted into it. Give the calculated values. If graphs are included, make the graphs an appropriate size. Label all axes and give each graph a title. If experiments are not quantitative, this section may be omitted.
8. Conclusions – Make a simple statement concerning what you conclude from the experiment. This is not a place to give your opinion of the lab and whether or not it was “fun”. It is not your job to review the lab like you would if you saw a movie.
9. Experimental error – If there is a known value for something you are doing in lab, calculate the experimental error.
10. Error Analysis – What are some specific sources of error, and how do they influence the data? Do they make the values obtained larger or smaller than they should be? Which measurement was the least precise? Instrumental error and human error exist in all experiments, and should not be mentioned as a source of error unless they cause a significant fault. Significant digits and mistakes in calculations are NOT a valid source of error. In writing this section it is sometimes helpful to ask yourself what you would do differently if you were to repeat the experiment and wanted to obtain better precision.
11. Questions – Answer any questions included in the lab directions. Answer in such a way that the meaning of the question is obvious from your answer.
Reporting Lab Data
Graphing Data
- All graphs should have a descriptive title (“Graph” is not a title) and a label. e.g. – Graph A: Density of Solutions with Varying Sugar Concentrations.
- Both the vertical and horizontal axes should both have labels and units clearly marked. Use a ruler to draw the axes.
- The scales chosen should reflect the precision of the measurements. For example, if temperature is known to be ±0.1ºC, you should be able to plot the value this closely. Don’t have each block of the graph equal to 10ºC.
- There should be a table in which the data values are listed. Don’t put data in a graph unless you have first listed it in a table.
- The controlled or independent variable is placed on the horizontal axis. The dependent variable is graphed on the vertical axis.
- There should be an obvious small point on the graph for each experimental value. It is not necessary to include the coordinates of each point since they will be in the data table.
- A smooth line should be drawn that lies as close as possible to most of the points. Do NOT draw a line connecting one point to the next as in a dot-to-dot drawing. If the line is a straight line, use a ruler to draw it.
- If a computer program is used to draw the graph, the rules still apply.
Accuracy
Accuracy is a measure of how close an experimental value is to a value which is accepted as correct. The measure of the accuracy of an experimental value is reported as Percent Error.
Data Tables
1. All data tables must be neatly organized. Numbers should be aligned by decimal point. Appropriate units must always be used.
2. Data should be appropriately spaced out so that there is room for corrections or annotations about the data.
3. All data must be in your lab notebook and initialed by the teacher before you leave the lab.
QRS lab
Reactions and explanations only, no full writeup.
In this lab, there are three flasks labeled Q, R, and S. Each flask contains one of the following solutions: 0.1 M Pb(NO3)2, 0.1 M NaCl, or 0.10 M K2CO3. Two other flasks are labeled X and Y. One of these flasks contains 0.1 M AgNO3 and the other contains 0.1 M BaCl2.
Mix each of the solutions with each of the other and record all observations. For all precipitates which form, you must write a balanced equation and net ionic equation and identify the precipitate. You will need to wait until you have identified the solutions to write the equations. As you carry out the reactions you must use as little solution as possible. Part of your grade is the way in which you are observed performing the reactions. Frugality is key. You must explain how you reasoned out the solution’s identity.
Qualitative Analysis of the Group III Cations
No writeup. Only data sheet.
Discussion
A known solution of the Group III cations (Cr3+, Al3+, Fe3+, Mn2+) and an unknown solution containing some combination of ions will be analyzed.
Group III contains those cations whose hydroxides do not precipitate under highly acidic conditions. Under basic conditions, however, the Group III cations will precipitate as the hydroxides.
Cr3+ (aq) + 3OH-(aq)® Cr(OH)3(s)
Al3+(aq) + 3OH-(aq) ® Al(OH)3(s)
Fe3+(aq) + 3OH-(aq) ® Fe(OH)3(s)
Mn2+(aq) + 2OH-(aq) ® Mn(OH)2(s)
The pH is then raised with NaOH and hydrogen peroxide is added to further oxidize the precipitates. The Fe(OH)3 (s) remains the same, the Mn(OH)2(s) becomes MnO2(s), the Cr(OH)3(s) oxidizes to the chromate ion CrO42-(aq) and the Al(OH)3(s) complexes with more hydroxide ion to form Al(OH)4-(aq).
MSDS
2M NH4Cl solution / Irritating to body tissues. Avoid all body tissue contact.6M Ammonia / Liquid and vapor are strongly irritating to skin, eyes, and mucous membranes. Vapor extremely irritating to eyes. May cause blindness. Toxic by ingestion or inhalation. When heated to decomposition, emits toxic fumes of NH3 and NOx.
6M NaOH / Moderately toxic by ingestion and skin absorption. Corrosive to body tissues. Causes severe eye burns. Avoid all body tissue contact.
3% H2O2 / Slightly toxic by ingestion or inhalation. Irritant to skin, eyes and respiratory tract. Avoid prolong body contact. Hydrogen peroxide will decompose rapidly when exposed to almost any substance.
3M H2SO4 / Moderately toxic by ingestion. Corrosive to eye, skin, and all other body tissues. Avoid all body tissue contact. Very considerable heat generated when diluted with water.
6M HNO3 / Corrosive; will cause severe damage to eyes, skin and mucous membranes. Moderately toxic by ingestion and inhalation. Strong oxidizer. Avoid contact with acetic acid and readily oxidized substances.
0.5M KSCN / Slightly toxic by ingestion. Irritating to body tissues. Avoid all body tissue contact. Contact with acids or heat may liberate poisonous hydrogen cyanide gas.
PbO2 / Moderately toxic by ingestion or inhalation. Irritating to body tissues. Avoid all body contact. Oxidizer. Lead and lead compounds are possible carcinogens.
6M HC2H3O2 / Substance not considered hazardous. However, not all health aspects of this substance have been thoroughly investigated.
0.1 M Pb(C2H3O2)2 / Moderately toxic by ingestion and skin absorption. Eye and skin irritant. Possible carcinogen. Avoid ingestion, inhalation and skin absorption. Chronic exposure to inorganic lead via inhalation or ingestion can result in accumulation in and damage to the soft tissues and bones.
Procedure
Obtain a Group III known sample which contains all of the ions. You will get a Group III unknown solution (which may contain any or all of these cations) after you have completed the known. All glassware should be cleaned, rinsed and rinsed with distilled water before starting the lab.
Step / Notes1. Place 1-2 mL of solution to be tested in a small test tube.
2. Add 1 mL of 2 M ammonium chloride solution to the sample in the test tube and stir. Add 6 M aqueous ammonia to the sample dropwise until the solution is just barely basic (remove a drop of the solution with a stirring rod and touch the drop to a strip of pH test paper).
3. Add about 3 mL of distilled water to wash the precipitate. Mix thoroughly, centrifuge, decant and discard water.
4. Add ~ 2mL 6M NaOH to the residue and mix.
5. Add 10 drops 3% H2O2 and mix immediately. Boil several minutes to remove excess H2O2. If solution is green, add more H2O2. (yellow is okay) Look for separation of precipitate and supernatant. Centrifuge, decant and obtain residue 2 for step 6, and decantate 2 for step 12. Do not discard. If necessary, recentrifuge decantate 2 until absolutely clear or filter into another test tube.
6. Add 1-2 mL 3M H2SO4 to residue 2. Mix.
7. Add 5-6 drops 3%H2O2 to hasten the process. Mix thoroughly. If it doesn’t dissolve, heat for a few minutes until all the solid dissolves.
8. Dilute solution to a total of 4 mL with distilled water and divide the solution into 2 parts to be tested for Fe3+ ions in step 9 and Mn2+ ions in step 10.
9. Add 1-2 drops 0.5M KSCN to one test tube from part 6. A blood red solution indicates the presence of Fe3+ ions.
10. To the other half of the solution from step 6, add ~ 1mL 6M HNO3 and mix.
11. Add solid PbO2 equivalent to 1/10 the volume of the liquid. Mix well and Boil for 2-3 minutes and let stand for 3 minutes. If Mn2+ ions are present, the solution will turn a pink to dark purple color. If test is negative, add another small portion of acid, mix and Boil solution. Centrifuge.
12. Dilute decantate 2 from step 4 to ~ 4mL with distilled water and divide into two parts to be tested for Al3+ in step 13 and CrO42- in step 14.
13. Add ~ 2mL 2M NH4Cl to the first half of decantate from step 12. DO NOT MIX. Place in Boiling water for 5 minutes. Look closely for a fluffy, translucent solid in the top layer which indicates the presence of Al3+ ions. If uncertain about the aluminum test, centrifuge. If other ions are present, the decantate may not be clear and a halo effect may be seen around the precipitate. The iron and manganese hydroxides will spin down first because of the greater densities and the aluminum hydroxide will be on top.
14. Add 6M HC2H3O2 to second half of decantate from step 9 until acidic to litmus paper. Add 1-2 drops 0.1 M Pb(C2H3O2)2. Let stand for 3 minutes. A white or yellow precipitate is a positive test for CrO42- ions.
Unknown #______Station #______