Experiment 2 Physical Properties

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					                Experiment 1
              Physical Properties




Valdosta State University
Goal
To identify an unknown substance based on its physical
  properties.




  Valdosta State University
Background
Physical Property – Characteristic of a substance which
  can be measured without changing the chemical identity
  of the substance.

Examples:             color
                      solubility
                      density
                      melting point
                      boiling point



  Valdosta State University
Background
Whole books have been published which contain nothing
 but physical properties

 Chemical Rubber Company Handbook of Chemistry and
                      Physics




  Valdosta State University
Background
In this experiment we will consider three physical
   properties:
    – Solubility
    – Density
    – Boiling point
These measured properties will then be compared to a
   table of known compounds to identify your unknown
   substance




  Valdosta State University
Technique - Solubility




  Valdosta State University
Technique - Solubility


 1.   Add 15 drops of solvent
      to a 10 x 75 mm test
      tube.




  Valdosta State University
Technique - Solubility


 1.   Add 15 drops of solvent
      to a 10 x 75 mm test
      tube.
 2.   Add 10 drops of
      unknown.




  Valdosta State University
Technique - Solubility


 1.   Add 15 drops of solvent
      to a 10 x 75 mm test
      tube.
 2.   Add 10 drops of
      unknown.
 3.   Mix




  Valdosta State University
Technique - Solubility


 1.   Add 15 drops of solvent
      to a 10 x 75 mm test
      tube.
 2.   Add 10 drops of
      unknown.
 3.   Mix
 4.   Observe


                                 Miscible   Immiscible
                                (Soluble)   (Insoluble)


  Valdosta State University
Technique – Care Of The Electronic Balance
  1. Never place chemicals directly on a balance pan.
  2. Do not place hot objects on a balance pan.
  3. Inform your laboratory instructor if the balance is not
     level or at the zero mark when empty.
  4. Always make sure that the balance is at zero before
     you begin weighing and after you finish weighing.
  5. Immediately clean up any chemical spills on or near
     the balance.




 Valdosta State University
Technique - Using the Electronic Balance
  1. Check that the balance reads 0.000g, if not press
     the “ZERO” button.
  2. Place the empty container or weighing paper on the
     balance, wait for the balance to settle, and record
     the mass.
  3. Remove the container from the balance and place
     the substance or object to be weighed in the
     container.
  4. Replace the container on the balance, wait for the
     balance to settle, and record the mass.
  5. The mass of the sample can be obtained by
     subtracting the mass of the container from the mass
     of the container AND the mass of the sample.


  Valdosta State University
Technique - Using a Graduated Cylinder




 Valdosta State University
Technique - Using a Graduated Cylinder
1.     A graduated cylinder is a device used to accurately contain a
       known volume of a substance.




     Valdosta State University
Technique - Using a Graduated Cylinder
1.     A graduated cylinder is a device used to accurately contain a
       known volume of a substance.
2.     The cylinders are usually marked in units that are 1% of the
       cylinder’s total volume.




     Valdosta State University
Technique - Using a Graduated Cylinder
1.     A graduated cylinder is a device used to accurately contain a
       known volume of a substance.
2.     The cylinders are usually marked in units that are 1% of the
       cylinder’s total volume.
3.     To read the cylinder correctly, the volume must be read at the
       bottom of the meniscus.




     Valdosta State University
Technique - Using a Graduated Cylinder
1.     A graduated cylinder is a device used to accurately contain a
       known volume of a substance.
2.     The cylinders are usually marked in units that are 1% of the
       cylinder’s total volume.
3.     To read the cylinder correctly, the volume must be read at the
       bottom of the meniscus.
4.     To ensure an accurate reading, place the graduated cylinder
       on the counter and get at “eye-level” to read the cylinder.




     Valdosta State University
Technique - Using a Graduated Cylinder
1.     A graduated cylinder is a device used to accurately contain a
       known volume of a substance.
2.     The cylinders are usually marked in units that are 1% of the
       cylinder’s total volume.
3.     To read the cylinder correctly, the volume must be read at the
       bottom of the meniscus.
4.     To ensure an accurate reading, place the graduated cylinder
       on the counter and get at “eye-level” to read the cylinder.
5.     Be sure to record as many numbers (digits) as reasonable for
       the graduated cylinder you are using.




     Valdosta State University
Technique - Boiling Point




  Valdosta State University
Technique - Boiling Point
1.     Place 30 drops unknown liquid in a 10mm x 75mm test tube.




     Valdosta State University
Technique - Boiling Point
1.     Place 30 drops unknown liquid in a 10mm x 75mm test tube.
2.     Place a capillary tube into the test tube open end down.




     Valdosta State University
Technique - Boiling Point
1.     Place 30 drops unknown liquid in a 10mm x 75mm test tube.
2.     Place a capillary tube into the test tube open end down.
3.     Using a rubber band attach a thermometer to the test tube.




     Valdosta State University
Technique - Boiling Point
1.     Place 30 drops unknown liquid in a 10mm x 75mm test tube.
2.     Place a capillary tube into the test tube open end down.
3.     Using a rubber band, attach a thermometer to the test tube.
4.     Place the entire apparatus into a water bath.




     Valdosta State University
Technique - Boiling Point
1. Warm the water bath (and your apparatus) on a hot
   plate until a fast, steady, stream of bubbles appears at
   the capillary.
2. Remove the water bath from the heat using beaker
   tongs.
3. Watch the apparatus carefully. When the bubbles quit
   emerging from the capillary, read the thermometer.
   This is the boiling point of the liquid.




  Valdosta State University
Example Data
Part A - Solubility                         Soluble        Insoluble
1. Solubility in water                      ___S____       ________
2. Solubility in 95% ethanol                ___S____       ________
3. Solubility in acetone                    ___S____       ________
4. Solubility in cyclohexane                ___S____       ________

Part B - Density of Liquid                  Trial #1           Trial #2
1. Mass of 10 mL graduated cylinder         _25.312 g__     _25.313 g__
2. Mass of 10 mL grad. cylinder + unknown   _27.463 g_      _27.855 g__
3. Mass of unknown                          __2.151 g_      __2.542 g__
4. Volume of unknown                        __2.8 mL_       __3.1 mL__
5. Density of unknown                       _0.77 g/mL_     _0.82 g/mL_
6. Average density of unknown                        _0.795 g/mL___

Part C - Boiling Point of Liquid            ___68oC__      _72oC___
Average Boiling Point of Liquid                         70oC

    Valdosta State University
Example Data
Solubility:
Water, Acetone, Ethanol, Cyclohexane
Matching Compounds:
  Substance             Density(g/mL)   Boiling Point(oC)
  Acetone                  0.79               56
  2-Butanone               0.81               80
  t-Butyl alcohol          0.79               82
  Ethanol                  0.79               79
  Ethyl Acetate            0.90               77
  Methanol                 0.79               65
  1-Propanol               0.80               97
  2-Propanol               0.79               82


   Valdosta State University
Example Data
Density: 0.795 g/mL
Matching Compounds:
  Substance             Density(g/mL)   Boiling Point(oC)
  Acetone                  0.79               56
  2-Butanone               0.81               80
  t-Butyl alcohol          0.79               82
  Ethanol                  0.79               79
  Ethyl Acetate            0.90               77
  Methanol                 0.79               65
  1-Propanol               0.80               97
  2-Propanol               0.79               82




  Valdosta State University
Example Data
Boiling Point: 70oC
Matching Compounds:
  Substance            Density(g/mL)   Boiling Point(oC)
  Acetone                 0.79               56
  2-Butanone              0.81               80
  t-Butyl alcohol         0.79               82
  Ethanol                 0.79               79
  Ethyl Acetate           0.90               77
  Methanol                0.79               65
  1-Propanol              0.80               97
  2-Propanol              0.79               82




  Valdosta State University
Example Data
Based on the data, the unknown is:
                        Methanol

• Notice that the data did not fit exactly




  Valdosta State University
                              Format

• Even though two students may be sharing a drawer,
  each student is to do the experiment individually.
• In other words, each student will do their own
  experiment. Failure to do so could result in a grade of
  “0” for the laboratory.




  Valdosta State University
                  Addition to the unknowns
• Please add the unknown MTBE to the list of possible
  unknowns.
• Its physical properties are as follows:
  Solubility
       Insoluble in water
       Soluble in 95% ethanol
       Soluble in acetone
       Soluble in cyclohexane
  Boiling point is 55 ºC
  Density is 0.74 g / mL


  Valdosta State University
Safety

• Unknowns and solvents (acetone, ethanol and
  cyclohexane) are flammable
• Glassware and stands may be hot. Use beaker tongs to
  remove the hot water baths from the hot plates.




  Valdosta State University
Waste Disposal

Solvents and unknowns go into the container in fume hood
  marked “Recovered Organics Without Halogens”.




  Valdosta State University

				
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