Chemistry for Everyone
DeLorenzo's Four Interesting Mysteries Verified Josefina Ma. Ferriols-Pavico Research and Development Management Office, Lyceum-Northwestern University, Tapuac District, Dagupan City, Pangasinan 2400, The Philippines;
[email protected] I am a biochemistry instructor at the Lyceum-Northwestern University in the Philippines, and I was fascinated by the article Four Interesting Mysteries with Seemingly Conflicting Explanations written by Ron DeLorenzo, which appeared in the April 2000 issue of this Journal (1). This paper verifies the four mysteries DeLorenzo discussed, which also served as a springboard for critical thinking. I have always lived with the adage that you don’t accept everything with absolute certitude, and thus I always check my resources. I was eager to share DeLorenzo’s information with my students, who are in their late teens (17 to 19) and enrolled in undergraduate paramedical courses such as Bachelor of Science in Biology, Chemistry, Pharmacy, Medical Technology, Optometry, and Dentistry. Together with my students, I investigated and designed new experiments for my biochemistry laboratory class to enrich my students’ understanding and appreciation of the direct connection between biochemistry and their personal lives. The following is a brief description of the methodologies, the results obtained, the inferences, and the recommendations for each investigation. DeLorenzo’s Mystery No. 1: Why might women become intoxicated more easily than men? DeLorenzo wrote: Women become intoxicated more quickly and suffer harsher consequences from consuming alcohol than men. The reason: women have a greater percentage of body fat compared to men. This leaves fewer polar aqueous fluids in which alcohol can dissolve. Alcohol is polar and readily dissolves in water which is polar. Polar alcohol does not readily dissolve in nonpolar fat.
The insolubility of alcohol in body fat indicates that the alcohol will concentrate itself in the polar aqueous fluids and
thus increase the tendency of females to become intoxicated. To verify if women indeed became intoxicated more quickly than men and to relate this phenomenon with the solubility of alcohol in water and the higher lipid content of women, I devised two experiments.
Experiment 1: Solubility Test Methodology: We tested the solubility of alcohol in water and in oil. Result: Ethyl alcohol dissolved in water, but formed two layers with oil. Upon shaking the alcohol–oil mixture, the two layers formed a temporary emulsion which later separated into two layers again. Inference: The above result supports the statement that the polar alcohol will concentrate itself in the lesser water content in females. Experiment 2: Gender-Related Sensitivity to Alcohol Experiment: We selected three males and three females who had approximately the same build. We measured their blood pressure before drinking, and 30 minutes after drinking a glassful (100 mL) of red wine. After 30 minutes, we asked them if they felt dizzy or felt tremors in their body. We also checked their face for redness or flushing. Each was asked to walk a straight line to test for muscle coordination. Result: The female students did feel intoxicated more quickly than the male students. A graph showing the trend in the blood pressure showed a general reduction in both male (Fig. 1) and female students (Fig. 2), but the lowering was more pronounced in the females. The decrease in the males was about 10 units for the systolic and the diastolic. In the females, the decrease in the systolic ranged from 10 to 30 units while the diastolic remained the same in one, and decreased from 20 to 30 units in the two other females. Both male and female students passed the muscle coordination test without difficulty.
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Figure 2. Blood pressure of three females before and after drinking red wine.
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Chemistry for Everyone
Inference: This experiment indicated that females do get intoxicated more easily than males. Alcohol is a vasodilator, which accounts for the lowering of the blood pressure. The amount of wine (100 mL) that the subjects drank was not enough to adversely affect their muscle coordination. Recommendations: To further improve the experiment, the following are recommended: 1. Warning: Drink in small amounts! Sip is the word. Do not drink the wine in one gulp. A male student, who was not part of the experimental group, sneaked a 100mL drink of the red wine in one gulp and felt dizzy immediately. His classmates took his blood pressure (120/100) and according to the dizzy student, it was higher than his usual blood pressure (100/80). 2. Monitoring: Pulse rate can also be monitored to complement the blood pressure measurements, or in cases where there is no sphygmomanometer available. Instead of walking a straight line, we can take handwriting samples before and after the experiment. Tremors in the hands can show through the handwriting. With the aid of a tape recorder and a stopwatch, test the subjects’ ability to do tongue twisters before and after drinking. Count how many tongue twisters they can do within a span of one minute. 3. Efficacy: To improve the efficacy of the experiment (i.e., to be able to see the results more clearly) the students suggested increasing either the volume of the wine or the strength, or taking it on an empty stomach instead of full. But to play safe, an empty stomach should be avoided.
Mystery No. 2: Why might alcohol consumption enhance cigarettes’ carcinogenic effects? Experiment: We obtained two used cigarette butts and peeled off the paper coating. One brown butt was inserted in a test tube containing alcohol and the other was placed in a test tube containing only water. We then tested for the presence of the alkaloid nicotine in the solvents using Mayer’s test and Wagner’s test (preliminary tests for the presence of alkaloids). Result: The solution in the test tube containing alcohol turned brown immediately, demonstrating that the tar easily dissolves in alcohol. The solution in the test tube containing water as solvent took more time before it turned brown. The brown color of the alcoholic medium was more intense than that of water. For the Mayer and Wagner tests, precipitation was observed in the alcoholic extract, whereas slight to negligible precipitation was observed in the aqueous solution. The formation of a precipitate was a qualitative indication for the presence of an alkaloid. Inference: This indicates that nicotine, which is an alkaloid, is more soluble in alcohol than in water. Thus, smoking and drinking alcohol can increase the solubility of cigarette tar in the cigarette smoke, easing the transport and passage of the tar into the body of the smoker.
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Mystery No. 3: Why do latex birth control devices used with oil-based lubricants permit unwanted pregnancy and promote the spread of HIV more than latex condoms used with water-based lubricants? Experiment: A latex condom was cut into 12 pieces (2.5 × 2.5 cm). Three pieces served as the control, and the rest were immersed for five minutes in various lubricants. Three pieces were immersed in a beaker of water and another three in saliva, both sets to represent water-based lubricants. The last three pieces were immersed in a beaker of mineral oil to represent oil-based lubricant. After five minutes, the pieces were patted dry and placed on a ruler to measure if the lubricant affected the length. The pieces were then held at both ends, pulled, and stretched out over the ruler to measure the effect on the mechanical strength of the latex. Result: The pieces of latex immersed in water and in saliva floated on the surface with the ends coiled inward, whereas those in oil were spread out and sank to the bottom of the beaker. After five minutes, the lengths of the control pieces immersed in water were unchanged. A slight expansion in the length of the latex piece immersed in saliva was noted. These were all able to stretch to twice their original length without snapping and to spring back to form. The latex pieces immersed in mineral oil for 5 minutes increased in length from 2.5 cm to 3.5 cm. Stretching the oil-immersed pieces proved catastrophic: two of them snapped, and the third was able to stretch to twice its length but was not able to spring back to its original length. The oil-immersed pieces were also thinner than those in the water control group. Inference: The experiment was able to demonstrate the reduction of the mechanical strength and elasticity of the latex condom immersed in an oil-based lubricant. Mystery No. 4: Why does red meat go well with red wine and white meat goes best with white wine? DeLorenzo attributes this to the tannic acid present in red wine, which acts as a surfactant in cleaning the tongue desensitized by the fat from the red meat. White meat has less fat and does not need the action of the tannic acid. Experiment: We tested the solubility of a pea-sized mass of solid tannic acid in alcohol and in oil. Result: The tannic acid dissolved in both the oil and the alcohol. Inference: This supports DeLorenzo’s statement that the fats from the red meat will be dissolved by the tannic acid. Tannic acid in red wine can emulsify the oil with the alcohol and help dissolve the fats. In the test for the solubility of alcohol in oil, the oil and alcohol were immiscible and produced only a temporary emulsion. The test tube with alcohol represented white wine and showed the inability of white wine to emulsify the fats. Tannic acid in alcohol represented red wine and showed the ability of red wine to emulsify the fats present in red meat. This may also lend insight into why red wine is a more healthful drink in reducing heart diseases and cholesterol levels than white wine.
Journal of Chemical Education • Vol. 79 No. 10 October 2002 • JChemEd.chem.wisc.edu
Chemistry for Everyone
Student Response
Acknowledgments
The response of the students to the new experiments was overwhelming. They appreciated the new insights and the connection to real life situations. Most of all they enjoyed drinking the red wine. They were squeamish with the latex experiment; for most of them, this was their first encounter with this latex contraceptive device. They were amazed at how quickly the oil could weaken the condom. They also realized that laboratory experiments need not be too academic and that even the seemingly innocent solubility tests do have a vital relevance in our personal lives. These future biologists, chemists, pharmacists, optometrists, and dentists took part in suggesting improvements to the experiment. Personally, I grew another dimension in trying out these new experiments. Though simple they bring with them profound knowledge and insights.
I thank the following people who contributed to the completion of this paper. David Livingstone Ramos, Assistant Professor of the Natural Sciences Department, for his repeatedly providing personally used cigarette butts at the expense of his health; Reynald Bautista, a persevering Lycean B.S. Pharmacy student for performing the Mayer and Wagner confirmatory tests for alkaloids, and the many curious, adventurous, and observant students in my biochemistry laboratory. I also thank Francisco T. Duque for selecting to provide our library with this wonderful Journal, among other journals. Literature Cited 1. DeLorenzo, R. J. Chem. Educ. 2000, 44, 475–476.
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