Formation of an Alkene by Alcohol Dehydration Essay Example for Free

Formation of an Alkene by Alcohol Dehydration Essay Beer’s Law is an empirical relationship that relates the absorption of light to the properties of the material through which the light is travelling. In turn, absorbance is proportional to concentration and the higher the concentration, the higher the absorbance. This experiment incorporated Beer’s Law and is focused on determining the stress that various alcohols have on biological membranes. Using five solutions of differing alcohol concentration for each of the three alcohols; methanol, ethanol, and 1-propanol and a small slice of beet, the stirred solution was placed into a plastic cuvette and then into a spectrophotometer and the absorbance of alcohol solutions were determined in order to conclude which alcohol and concentration of alcohol had the greatest effect on biological membranes. The results showed that the most non-polar of the alcohols being tested, 1-proponal, caused the greatest damage to the biological membrane, the beet cell’s vacuole. INTRODUCTION The boundary between any cell and its environment is the plasma membrane, composed of a matrix of phospholipids molecules with many different kinds of proteins. Membranes have different properties and a variety of functions, in large part determined by the specific proteins within the membrane. The purpose of this experiment is to observe the effects of various alcohols on biological membranes, to determine the stress that various alcohols have on biological membranes and to conclude which concentration of alcohol has the greatest effect on biological membranes. The central plant vacuole of plant cells contains water and solutes, including water-soluble pigments. Its membrane, the tonoplast, is normally poorly permeable to water. The central plant vacuole of the root cells of beet contains a water-soluble red pigment, betacyanin, which gives the beet its characteristic color. Since the pigment is water-soluble and not lipid soluble, it remains in the vacuole when cells are healthy. If the tonoplast and the plasma membrane are damaged, the vacuole’s contents will leak out into the surrounding environment. Membrane disruption generally occurs when the cell is dead. Methanol, ethanol and 1-propanol are very similar alcohols, differing only in the number of carbon and hydrogen atoms within the molecule. One possible reason why these alcohols are so toxic to living organisms is that they might damage membranes. The polarity of methanol, ethanol, and 1-propanol comes from the OH group where the electrons are affected. The longer the R group the less the attraction. If 1-propanol is the most non-polar alcohol of the alcohols being tested, then 1-proponol will cause the greatest damage to the biological membrane, the beet cell’s vacuole. The effect of three different alcohols, methanol, ethanol, and 1-propanol, were tested on the beet vacuole membranes in this experiment. A measure of absorbance was collected using a conductivity probe. If a beet cell’s vacuole membrane (the tonoplast) was damaged, the red pigment, betacyanin, leaked out of the cell. The more red pigment that leaked out into the surrounding environment and the more intense the pigment, the greater the absorbance and the amount of cellular damage sustained by the beet. RESULTS The absorbance of methanol, ethanol, and 1-propanol were collected after the alcohol solutions of differing concentrations were placed in the plastic cuvette and then into the spectrophotometer. The absorbance of methanol, ethanol, and 1-proponal followed a general trend; the absorbance of the alcohol increased in relation to the rise in concentration of each alcohol solution. Figure 1. The graph depicts five solution of differing alcohol concentrations for each of the three alcohols; methanol, ethanol, and 1-propanol. The alcohol with the highest measurement of absorbance was the non-polar 1-proponal. (Figure 1) DISCUSSION The results (Figure 1), in general, support the original hypothesis that if 1-propanol is the most non-polar alcohol of the alcohols being tested, then 1-proponol will cause the greatest damage to the biological membrane, the beet cell’s vacuole. Hence, 1-proponal had the highest absorbance. The polarity of methanol, ethanol, and 1-propanol comes from the OH group, where the electrons are effected. The longer the R group the less the attraction between the molecules. In turn, methanol, ethanol, and 1-propanol are arranged from most polar to non-polar. At concentrations of 20% methanol, 10% and 20% ethanol, and 20% 1-propanol, the absorbance did not follow the general trend of data. This is due to sources of error in this experiment. There proved to have many sources of error in this experiment given the data gathered in this study and the evidence to this point. Sources of error include the size and surface area of the beat, cross contamination, and puncturing the beet during the stirring of solution. If the size and surface area of the beet slices were not uniform, bigger slices of beets had the potential to secrete a larger quantity of red pigment and a greater intensity in color in turn, increasing the absorbance. If the alcohol solutions were not stirred in order from lowest concentration to highest concentration, cross contamination would have occurred. If lower concentrations of alcohol are diluted with higher concentrations of alcohol, the absorbance of the lower concentration of alcohol will increase. If the beet was punctured during the stirring process, a greater amount of red pigment leaked out into the surrounding environment and in turn, the absorbance is increased. Beer’s Law is an empirical relationship that relates the absorption of light to the properties of the material through which the light is travelling. Beer’s Law is represented as A = ? bc (1) Where A is equal to the absorbance, ? is equal to the molar absorbtivity, b is equal to path length, and c is equal to concentration. In turn, absorbance is proportional to concentration and the higher the concentration of the red pigment that leaks out into the surrounding environment, the higher the absorbance of the alcohol.