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LAB 3 - Titration

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LAB 3 - Titration Powered By Docstoc
					100 Points                                                                     DUE: December 3rd, 2012
Name _________________________________________________________ Period _______ Date __________________


                                                LAB 3: Titration (DCP/MS)

Introduction:

A titration is a laboratory process where a measured amount of a solution with a known concentration is added to a
known volume of a second solution with an unknown concentration until the reaction between them is complete.
Through the molarity ratio, the concentration of the unknown solution can then be calculated. You are going to be
recording volume of the titer (base) added and the pH in order to graph a titration curve and determine the equivalence
point.


Materials/Equipment:
    60 mL of 0.200 +/- 0.010 M Ammonium Hydroxide
    50 mL of 0.100 M Hydrochloric Acid
    ~1 mL of Universal Indicator Solution
    Buret
    Buret Clamp
    Stand
    Distilled Water
    Soap Water
    250 mL beaker
    150 mL beaker
    Funnel
    50 mL graduated cylinder (ACID only!)
    100 mL graduated cylinder (BASE only!)
    Lab Quest
    Vernier pH probe
    Timer


Hazards:
    SAFETY GLASSES MUST BE WORN AT ALL TIMES!

      Ammonium Hydroxide (NH4OH) →                         POISON! Very hazardous in case of skin contact (corrosive,
       irritant, permeator), of eye contact (irritant), of ingestion. Non-corrosive to the eyes. Non-corrosive for lungs.
       Liquid or spray mist may produce tissue damage particularly on mucous membranes of eyes, mouth and
       respiratory tract. Skin contact may produce burns.


      Hydrochloric Acid (HCl) →                         POISON! Very hazardous in case of skin contact (corrosive,
       irritant, permeator), of eye contact (irritant, corrosive), of ingestion. Slightly hazardous in case of inhalation
       (lung sensitizer). Non-corrosive for lungs. Liquid or spray mist may produce tissue damage particularly on
       mucous membranes of eyes, mouth and respiratory tract. Skin contact may produce burns.


      Universal Indicator Solution →          Stable, but may be moisture sensitive. Highly flammable. Treat as if this
       material were pure ethyl alcohol, so incompatible with strong oxidizing agents, acids (in principle, but since the
       indicator is present to measure pH, short term-exposure to acids is likely and should not have too harmful an
       effect), acid anhydrides, alkali metals, ammonia, peroxides.
100 Points                                                                                   DUE: December 3rd, 2012

               DO NOT FORGET TO RECORD YOUR ERROR/UNCERTAINTIES AND QUALITATIVE DATA!
Procedure:
   1. Clean the following equipment using the soap solution and rinsing it with the distilled water:
           a. 150 mL and 250 mL beakers
           b. Funnel
   2. Rinse the buret with distilled water (NO SOAP!) and drain it into the sink
   3. Go the fume hood and complete the following:
           a. Using the 100 mL graduated cylinder, obtain 60 mL of base and pour it into the 150 mL beaker
           b. Measure out exactly 50 mL of acid using the graduated cylinder and place it in the 250 mL beaker
           c. Put 15-20 drops of universal indicator solution in the 250 mL acid beaker
   4. Make sure that the stopcock on the buret is closed!
   5. Using the funnel, fill the buret up to the zero mark with the base
   6. Once the buret is filled, place the acid solution under the bottom of the buret
               Set up the pH probe (pH probe error = +/- 0.050) by doing the following:
           a. Remove the probe from the storage solution making sure not to spill the solution
           b. Note the probe number to make sure you use the same probe for each trial
           c. Rinse the probe very thoroughly with distilled water in the sink
           d. Place the probe in the acid beaker making sure is doesn’t tip over
           e. If not already, connect the probe to CH 1 on the side of the Lab Quest
           f. Turn on the Lab Quest and allow it to boot the program
           g. The program should load and give you a pH reading, it should stabilize roughly around 1
                        **Please let me know if you have trouble or if it doesn’t register the probe**
   7. Start the titration by doing the following:
           a. Add 2 mL of base approximately every 30 seconds and record the best pH reading and color (the reading
               may drift, but be consistent as to when you take your measurements). Gently stir the solution with the
               pH probe after each addition.
           b. When you have titrated 16 mL, add 1 mL increments every 30 seconds and record the best pH reading
               and the color
           c. When you have titrated 34 mL and have passed the equivalence point, return to 2 mL increments every
               30 seconds and recording the pH and the color
           d. Stop the titration when you have titrated about 40-44 mL or as time permits
   8. Clean up the titration by emptying the remaining base into the beaker and then pour all of the solutions into the
       waste beaker in the fume hood
   9. Clean all glassware with soap, except the buret and the probe
   10. Rinse the buret and probe with distilled water and carefully return the probe to its storage solution

Data Collection and Processing:
    All raw qualitative and quantitative data shown
    Titration graphs included (inserted into the report, not separate printouts)
    Calculation of acid concentration for each titration
    Calculation of the equivalence point for each titration
    All error/uncertainties must be shown and propagated
    A percent error calculation must be completed based on your accuracy of the unknown acid concentration
    All data must be in a table or graph with error (bars) and units

				
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