aspirin lab. chemistry ii honors virginia hall may 2, 2006

Aspirin Lab

Chemistry II Honors

Virginia Hall

May 2, 2006

Partners in Crime

• Astiney Mi’Cheal Clark

• Arlesia Hannah Malone

History of Aspirin

Aspirin or acetylsalicylic acid, is a derivative of salicylic acid that is a mild, nonnarcotic analgesic useful in the relief of headache, muscle

and joint aches. The drug works by inhibiting the production of prostaglandins, body chemicals that are necessary for blood clotting

and which also sensitize nerve endings to pain.

The father of modern medicine was Hippocrates, who lived sometime between 460 B.C and 377 B.C. Hippocrates was left historical records of pain relief treatments, including the use of powder made from the bark and leaves of the willow tree to help heal headaches, pains and

fevers.

By 1829, scientists discovered that it was the compound called salicin in willow plants which gave you the pain relief.

 Chemical and Written formula of Aspirin

Lab.png

C9H8O4

Salicylic Acid + acetic anhydride acetylsalicylic acid + acetic acid

Synthesis of Acetysalicylic Acid

Materials

Chemical materials: Equipment:

Salicyclic acid Test tubes

Acetic anhydride Microscale Organic kit(parts of it)

Concentrated phosphoric acid Analytical balance

Distilled water Weighing paper

Hot plate

250 mL beaker, 2

Thermometer

Stirring rod

Filter paper

Water aspirator

Funnel

Micro pipette

Procedures (Page 1)

1)Pour approximately 40 mL of tap water into the 100 mL beaker. Place the beaker on the hot plate and turn the hot plate on to a power setting not greater than 5.

2) Write your name, in pencil , on a piece of filter paper. Using the analytical balance, determine its mass and record this number on the data table.

3) With the filter paper still on the balance, tare (zero) the balance. Weigh out between 135 and 140 milligrams of salicylic acid directly onto the filter paper. Record the mass (all four decimal places!) in the data table. Place the acid in a test tube from the microscale kit.

4) Add 1 drop of concentrated phosphoric acid to the test tube.

5) Using the syringe from your microscale kit, add 0.3 mL of acetic anhydride to the test tube. Try to rinse all the other ingredients to the bottom of the test tube when adding the acetic anhydride.

6) Use a stirring rod to mix the reactants thoroughly.

Procedures (Page 2)

7) When your water bath (from step 1) is between 70 degrees Celsius and 90 degrees Celsius then, place the test tube in the water bath to heat its contents. You are trying to dissolve the salicylic acid and may need to stir contents of the test tube while it is in the water bath.

8) Once the acid is dissolved, heat for two more minutes, then cautiously add 0.5 mL of distilled water.

9) Remove the test tube from the water bath and allow it to cool to room temperature.

10) Crystallization should occur at room temperature; if if doesn’t, use a stirring rod to scratch the inside of the test tube.

11) Once crystallization has started, cool the test tube in a cup of ice water for several minutes, until crystallization is complete. Be careful not to let the tube tip over and spill into the ice water.

12) Line the Hirsh funnel from your microscale kit with the filter paper you weighed previously. Your instructor will show you how to do this.

Procedures (Page 3)

13) Using a spatula, transfer the contents of the test tube to the filter paper. Make sure you get all of the product; you may rinse the test tube with ice water if necessary ( the rinse water goes into the funnel as well).

14) Filter your product using either the vacuum pump or the sink-mount vacuum aspirator (again, your lab instructor will show you how to do this).

15) Once you’ve finished filtering the product, leave the filter paper and product in the fume hood to dry overnight.

16) Clean your lab station by rinsing all the glassware and the funnel. Return the equipment to its proper place.

17) Once the product is dry, weigh the filter paper and product and record in the table. Calculate the mass of the dry product.

Data

Data

0.1

39

0.2

83

0.1

75

0.1

08

0.3

14

0 0.1 0.2 0.3 0.4

1

2

3

4

5

Numbers in grams

Series1

Series1 0.139 0.283 0.175 0.108 0.314

1 2 3 4 5

Results

Our results were accurate as far as numbers go. We were able to successfully accomplish what this experiment was intended to do. We went through the process of weighing the salicylic acid and filter paper to determine the synthesis of acetylsalicylic acid.

We did our lab successfully. We followed directions correctly. We also made sure our measurements were accurate.

In Context to Purity

This was our foundation to see if our sample were pure. The more accurate we were in our measurements the more accurate it is for our sample to be pure. If were off at this stage it would throw the complete process of purity off. So this was basically the beginning.

Determination of Melting Points

Materials

Chemical Material: Equipment:

samples of solid organic compounds Mel-Temp apparatus

soap Thermometer

water Pestle

Watch glass

Capillary tubes (9)

Procedures

1) Your instructor will tell you which compound to use for practice. Place a small amount - no more than a few grains - of the practice compound on a watch glass. Use a pestle to gently grind it into a fine powder.

2) Take the pestle over to the sink - away from any heat source - and rinse any excess compound off the pestle with soap and water. Dry the pestle thoroughly with a paper towel and bring it back to your lab station.

3) Push the open end of the capillary tube into the compound on your watch glass. Some of the compound will now be in the top of the tube. Gently tap the closed end of the tube on the bench top. This will pack the compound down in the closed end of the tube. Repeat this a couple of times until you have about 0.5 cm of the compound in the bottom of the tube (about half the width of your little finger, unless you have tiny hands).

4) Place the capillary tube in the chamber of the Mel-Temp apparatus and turn on the unit. Start with a setting of 1 or 2 and increase the power only in small increments as needed, and never above 5. Heating your compound slowly is the key to getting good results!

Procedures (Page 2)

5) Observe the sample chamber frequently to make sure you don’t miss the melting point of your material. Heat the compound slowly and record the temperatures at which the compound begins to melt and the temperature when all of it has melted.

6) Use the table on the data sheet to identify your practice compound.

7) After everything has had a chance to cool down a bit, repeat the above procedure for an unknown compound. Make sure you record which sample you have!

Data

• The standard melting point range of

acetylsalicylic acid is 135-136 degrees

Celsius.

Results

By looking at the standard melting point for acetylsalicylic acid. We have concluded that ours was a tad off. It began to melt a little earlier and it stopped almost at the melting point according to our data sheet.

In Context to Purity

The boiling point of a substance is the temperature at which it can change its state from a liquid to a gas throughout the bulk of the liquid. A pure compound will have a definite melting point; therefore the identity of a substance can be determined or the purity of a substance can be determined. Ours was a little off making it impure to be aspirin since it was not a distinct melting point.

Relative Purity Test

Materials

Chemical Material: Equipment:Salicylic acid Test tube

Walgreen sample

Pure Aspirin

Arlesia and Astiney’s sample

Chemistry One sample

Iron (III) Chloride

Procedures

Test the product for relative purity as follows. Place a few crystals of salicylic acid in one test tube; in a second and third, place a little crushed commercial aspirin; in the fourth test tube, add a few crystals of your prepared aspirin and in a fifth test tube, add a few crystals of the chemistry I aspirin sample. Now add a few drops of iron (III) chloride to each tube and shake to mix the contents. Observe and record the results.

Data

Chemical Compound Color Observed after Iron (III) Chloride addition

Salicylic acid Violet/ Purple

Commercial 1: Walgreen Cloudy clear with pellets

Commercial 2: Pure Purple/ Lavender

A&A Aspirin Translucent Pink

Chemistry I Aspirin Translucent pink yet vague

Results

Many phenols (R-OH) produce colored coordination compounds with iron (III) ions. These complex anions are composed of 6 molecules of the phenol combined with 1 iron (III) ion. Since salicylic acid has a phenolic- OH group, it produces the positive (purple) test with iron (III) chloride. When SA reacts completely to produce ASA, the phenolic group is replaced with an acetate (acetyl) group, so the iron test would be negative. Of course, students will not get 100 % yield, so some SA remains to make their sample purple in the iron test. Thus since our sample did not turn purple, we instantly found out that our sample was impure.

In Context to Purity

Being that using the iron (III) chloride would be an indication of purity, the solution turning purple is a dead give away of being pure.

Standardization of Pipette

Materials

Pipette

Procedures

Take your pipette and count the number of drops it takes to make 1 mL. Repeat twice more.DO NOT loose your pipette or you will be

standardizing a new pipette.

Data

Number of Drops per 1mL

Trial 1 32

Trial 2 30

Trial 3 35

Calculations

Formula for Average # of drops per 1 mL = T1 + T2 + T3 / 3

Average: 32

Formula for # of mL per drop: 1drop * 1 mL

1 # of drops

1 drop : 1/32 or 0.03125

Results

In conclusion, we found that in standardizing the pipette, we were able to calculate any numbers of drops necessary for this lab. In the three trials we conducted, the numbers varied. But that could be in response to erroneous counting, miscalculations or a number of other reasons. The risk of losing the pipette was our biggest problem; losing it would mean performing the lab all over again.

In Context to Purity

Being that we under went a series of trials with our next lab. We needed to make sure that each drop is accounted for. We needed to make sure that our results were as accurate as possible and one way is to ensure that we are using one pipette that will give us around the same number of drops every time.

Spectrophotometric Analysis of Aspirin

Materials

Chemical Material: Equipment:

Chalk Spectrophotometer 20-D

water 4 Cuvettes

Paper towels

Procedures (Part 1: Making Standards)

1. Mass 403 mg of pure in a 250 mL Erlenmeyer Flask. Add 10 mL of a 1 M NaOH solution to the flask, and heat until the contents begin to boil.

2. Quantitively transfer the solution to a 250 mL volumemetric flask, and dilute with distilled water to the mark.

3. Pipet a 2.5 mL sample of this aspirin standard solution to a graduated cylinder to . Dilute to the mark with a .02 M iron (III) solution. Label this solution “A” and place it in a 250 mL Erlenmeyer flask.

4. Prepare similar solutions with 2.0, 1.5, 1.0, and .5 mL portions of the aspirin standard. Label these “B, C, D, and E.”

Procedures (Part II: Making an unknown from a tablet)

1. Place one aspirin tablet in a 250 mL Erlenmeyer flask. Add 10 mL of a 1 M NaOH solution to the flask, and heat until the contents begin to boil.

2. Quantitively transfer the solution to a 250 mL volumetric flask, and dilute with distilled water to the mark.

3. Pipet a 2.5 mL sample of this aspirin tablet solution to a 50 mL volumetric flask.

Procedures (Part III: Making an unknown from the product of the Micro scale

Synthesis of Acetylsalicylic Acid lab.)

1. Mass all of the acetylsalicylic acid product and record the mass in the data section. Place it in a 125 mL Erlenmeyer flask. Add 10 mL of a 1 M NaOH solution to the flask, and heat until the contents begin to boil.

2. Quantitatively transfer the solution to a 250 mL volumetric flask, and dilute with distilled water to the mark.

3. Pipet 10 mL sample of this aspirin solution to a 50 mL volumetric flask. Dilute to the mark with a 0.02 M iron (III) solution. (When adding 0.02 M iron (III) solution, the color should be obviously purple. If it is not, stop adding the 0.02 M iron (III) solution, and alert your instructor.) Label this solution "unknown," and place it in a 125 mL Erlenmeyer flask.

Procedures (Part IV: Testing the Solutions.)

1. Turn on the spectrophotometer by twisting the front left knob clockwise. Allow the spec to warm up for 15 minutes.

2. Adjust the wavelength to 530 nm using the large knob on top of the spec.

3. With the sample compartment empty, set the instrument to 0%T using the zero control knob (front left knob).

4. Using a Kimwipe, wipe off the cuvet containing the blank (0ppm), and place this cuvet in the sample compartment, being sure to properly align it. (The line on the cuvet should match up with the notch on the instrument.) Close the cover.

5. Set the mode to absorbance. Using the trans/abs control knob (front right knob) set the absorbance to 0.000.

6. Record the absorbance of the 0ppm solution – this should be a cuvet of iron buffer.

7. Obtain absorbance readings for each of the other standard solutions. Record the results on the data sheet.

8. Measure and record the absorbance of the unknown. Record it on the data sheet.

Data (Page 1)

Solution Absorbance

T1 T2 T3

A -.016 -0.19 -.015

B -.065 -.057 -.062C -.101 -.097 -.099

D -.133 -.130 -.135

E .043 .048 .048

Unknown A .058 .057 .055

Unknown B -.027 .080 .076

Unknown C .067 .075 .074

Data (Page 2)

Averages of AbsorbanceSOLUTION AVERAGE

A -.016666

B -.061333

C -.400333

D -.132666

E -.190333

UNKNOWN A -.056666

UNKNOWN B -.061

UNKNOWN C -.072

Results

In completing this lab we were able to deduce the amount of aspirin as a specific kind of product. We were also able to decipher the purity of acetylsalicylic acid made in the Synthesis lab discussed earlier.

To better this lab we would have to ensure the first we had the sufficient chemicals and equipment for the task at hand. Another way would be to execute our measurements more carefully.

In Context to Purity

The wavelength associated with the complementary color is known as the wavelength of maximum absorbance,. A spectrophotometer is used to provide light of certain energy and to measure the absorption of that light. By comparing our sample to the other samples provided we were able to compare our absorbance and transmittance to other aspirin sample.

What does it mean to pure?

According to www.answers.com/ purity is a quantitative assessment of

homogeneity or uniformity. It can also mean being undiluted or

unmixed with extraneous material.

Is ours pure?

Why?

When performing the spectrophotometric analysis of aspirin lab, we accidentally over-diluted our aspirin sample. While pouring the distilled water into the volumetric flask, we

passed 50mL. We were supposed to be diluting the aspirin sample to a certain extent, but to over dilute it would mean damage the whole

lab. And that’s exactly what we did…There are many other factors as to why our lab

could have failed.

How can we improve it?

In order to improve this lab we will definitely need to measure our chemicals more carefully. This can only result in a better more efficient result from our lab. Another way to advance this lab would be to follow our procedures more precisely and to the point. We should also be allotted more time to perform such tedious labs. More time would mean less time to make mistakes.

Abstract

Purpose: The lab is about purity and the synthesis and analysis of aspirin. We want to see the purity of a store brand sample (Walgreen), our sample, Chemistry One sample, pure sample, and salicylic acid. Each has a slight variation in chemical composition which will allow for comparison to a known standard and allow for the analysis of purity. Methods: First the acetylsalicylic acid was made. Then Chemistry One students aspirin was created following the same procedures as Chemistry Two students. The other compounds were given to us by our instructor. We took these samples and performed a series of labs. One was Mel-Temp where we melted our compounds. We then had a pipette to standardize to ensure accuracy. We also used a relative purity test to quickly see if our compounds were pure. We used the spectrophotometers to compare absorbance levels- another way of checking for purity. Results and Conclusions: Our sample did not show purity. We came to this judgment by the series of experiments we performed. From the standard melting point range which was provided, we saw that the standard temperature and ours were pretty accurate and the Chemistry One sample was way off. The Walgreen sample was closer to the range than ours and pure was too complicated to see. With the relative purity test only two were clearly purple. The purple hue symbolized that it was pure. Ours was translucent pink. It was evident that it was not pure. Having a standardized pipette is very important to make sure that each drop that is made is accounted for. The spectrophotometer was used to detect the absorbance and transmittance levels of our samples. It is our belief that our lab went wrong at the very beginning where we made our sample and the very end where we may have diluted our mixture too much. The relative purity test initially indicated the purity of the samples from the beginning.

Percent and Theoretical yield

Percent yield is very important the efficiency of a particular laboratory of individual reaction.• THEORETICAL

C7H6O3 + C4H6O3 C9H804 + C2H4O2

.139g .3mL .108

.1395g .3mL .2g

.1375g x 1 mol S.A. x 1mol A.A. x 22.4L A.A. x 1000mL A. = 22.16mL Limiting reactant

1 139g S.A. 1 mol S.A. 1 mol A.A. 1L A.A. **NEED

.3mL A.A. x 1L A.A. x 1mol A.A. x 1mol A.S.A. x 180g A.S.A. =.0024g A.S.A. Theoretical

1 1000mL A.A. 22.4L A.A. 1 mol A.A. 1mol A.S.A.

.108 x 100 =4500% Percent yield10024

References

•Science in motion•Wikipedia

•www.answers.com/purityr=67 •www.ask.com

•www.google.com•Encarta

•The World Book Encyclopedia•The American Encyclopedia

The Scene of the Crime

Questions?????