SCH3U Final Lab Exam June 2013
In this investigation, you will combine your chemistry knowledge and laboratory skills to perform an investigation.
This experiment and the final written report are worth 10% of your final mark.
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You will be put into groups of 2 and will choose one of the following topics. Only 5 groups per topic.
 Synthesis and Analysis of Acetylsalicylic Acid (ASA)
 Determining the Formula of an unknown hydrated salt.
 Determine the Molar Volume of Oxygen Gas
 Determine the concentration of Vinegar.
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To be approved for your topic, you must complete the following:
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Develop a detailed procedure (including labeled diagrams of any laboratory equipment
setup).
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Include a list of all required materials and chemicals (include quantities unless already specified).
It is strongly suggested that you use the Internet and other written references to develop your
procedure. ** This initial phase will be evaluated for communication and thinking and
inquiry.
Important Dates:
Procedure and Materials Due Date:
Thursday May 23rd
Laboratory Periods:
Monday, June 10th and Tuesday June 11th
Final Report Due Date:
End of Class on Tuesday, June 11th .
NO EXCUSES & NO LATES ACCEPTED
WHAT IS DUE ON June 11th at the end of class with no excuses and no lates accepted.
o Research (typed, in your own words, referenced using APA and works cited)
o Materials, RE-WRITTEN (modified for YOUR lab)
o Labeled and referenced diagrams of equipment
o Procedure (RE-WRITTEN for YOUR lab)
o Observation table(s) (titled and neatly written)
o Analysis (neatly written, proper units, organized)
Procedure Notes for the Synthesis and Analysis of Acetylsalicylic Acid
Acetylsalicylic Acid (ASA) is the active component in Aspirin. The benefits of ASA were first observed
by the Chinese in 500 B.C. ASA can be prepared by reacting salicylic acid with acetic anhydride using
very SPECIFIC reaction conditions:
HC7H5O3(s) + C4H6O3(aq)  HC9H7O4(s) + HC2H3O2(aq)
Analysis:
 Determine the limiting reactant in this reaction (density of acetic acid anhydride is 1.0820 g/mL).
Calculate the theoretical yield.
 Calculate the percent yield of the ASA.
 Perform an analysis on the purity of your final product. (ex. melting point determination on Day 2)
 Identify the major sources of error and suggest how you could improve the percent yield.
Research:
1. Briefly summarize the current commercial synthesis process for ASA.
2. How it works in the body (method of action).
3. Discuss uses, benefits and risks of using ASA (cover everything from infants, pregnancy,
athletes, adults, etc.)
Procedure Notes for Determining the Identity of a Hydrated Salt
The formation of crystal lattices may involve the trapping of water molecules. By heating a hydrated
crystal the water can be removed. Calculation of the mass of water lost and information given as to the
composition of the salt itself will allow for the determination of the formula of the hydrated salt.
Analysis:
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Determine the percentage composition of the salt given from data supplied (will be given the day
of the lab exam).
Determine the empirical formula and formula unit for the salt.
Find the number of moles of anhydrous salt produced.
Determine the number of moles of water released from heating the salt.
Determine the formula of the hydrated salt.
Identify the major sources of error in this experiment and suggest how you could improve the
experiment to obtain greater precision.
Research:
1. Research the effect of road salt on the quality of water and sources of salt contamination.
2. Find a common hydrated salt and discuss its uses.
Procedure Notes for Determining the Molar Volume of Oxygen Gas
According to Avogadro's hypothesis, equal volumes of gases at the same temperature and pressure
contain the same number of molecules. The molar volume is usually measured at STP.
For this experiment, you will generate oxygen gas by decomposing potassium chlorate with a
manganese (IV) oxide catalyst in a 3:1 mixture. This reaction will only occur upon heating.
Analysis:
 Determine the mass of oxygen produced.
 Calculate the molar volume for the exact conditions of your experiment.
 Use the atmospheric pressure and a table of water vapour pressures with respect to temperature to
determine the pressure of the oxygen gas collected.
 Calculate the molar volume at STP and SATP. Compare these values to accepted values.
 Identify the major sources of error in this experiment and suggest how you could improve the
experiment to obtain greater precision.
Research:
1. Research how gases are used in medical anesthetics and undersea exploration.
2. Research how oxygen gas is produced and purified for commercial use in gas cylinders.
Procedure Notes for Determining the Concentration of a Sample of Vinegar
Vinegar contains approximately 5% acetic acid by volume. You will calculate the exact concentration
of a sample of 10.0 mL of vinegar by performing a titration with a standard solution of sodium hydroxide.
Based on the theoretical molar concentration of the vinegar, determine the concentration of sodium
hydroxide needed for the titration and an appropriate indicator to use. This experiment must be
performed three times to determine an average.
Analysis:
 Determine the balanced chemical equation for this reaction
 Determine the theoretical concentration of acetic acid. (mol/L)
 Calculate the concentration of the vinegar for each trial and the average concentration of the
vinegar(mol/L)
 Find the % error of the concentration average.
 Identify the major sources of error in this experiment and suggest how you could improve the
experiment to obtain greater precision.
Research:
1. Research how vinegar is prepared for commercial use.
2. Why is vinegar used to preserve pickles and other foods?