Internal Assessment: Rate of Evaporation
Mr. Frias/4th Period
Wheeler High School
How will changing the molar mass of alcohol affect the rate of evaporation, represented by the change in temperature over time, measured using a temperature probe? Research/Abstract
Alcohol is an organic compound in which the hydroxyl functional group, OH, is bound to a carbon atom. Its carbon center should be saturated; it should have single bonds to three other atoms. The different types of alcohols are determined by the kinds of CH2 groups while the number of CH2 groups there are tells you the volume of the alcohol. The acyclic alcohols are the most basic and one of the most important groups of alcohol. The general formula of acyclic alcohols is: CnH2n+1OH. There are different types of acyclic alcohols. The most commonly used form of acyclic alcohol is ethanol which is a clear, volatile, flammable liquid that boils at 78.4℃. It is used as an industrial solvent, car fuel, and as raw materials in the chemical industry. Ethanol is widely used as a solvent for human contact or consumption, including perfumes, flavorings, colorings, and medicines. Another type of acyclic acid is methanol, and it is also the simplest sort of alcohol. It is a clear liquid that resembles ethanol is odor and properties, but it has a slightly lower boiling point of 64.7℃. Methanol is mainly used as a solvent, antifreeze, raw materials, fuel, or as a denaturant for ethanol. Unlike ethanol, methanol is extremely toxic since one sip of methanol can cause permanent blindness. Two other kinds of acyclic acid are propan-2-ol and butan-1-ol. Just like ethanol, these two types of alcohols can be produced by the fermentation process. Propan-2-ol is a colorless, flammable chemical compound with a strong odor. It is the simplest kind of secondary alcohol which occurs when an alcohol carbons is attached to two other carbons. Butan-1-ol is a primary alcohol with a four carbon structure. Butan-1-ol is part of the group of “fusel alcohols” which has more than two carbon atoms and is soluble in water. It is used as an artificial flavoring that is present in many types of food and beverages such as butter, cream, ice cream, and candy. Pentan-1-ol is a 5 carbon atom. It is a colorless liquid with an unpleasant aroma. This alcohol can be prepared by the fractional distillation of fusel oil. Some uses for pentan-1-ol include being used as a solvent for coating CDs and DVDs, and it is also used as a replacement for gasoline. Each of these acyclic alcohols has a general formula as follows: ethanol is C2H5OH, methanol is CH3OH, propan-2-ol is C3H7OH, butan-1-ol is C4H9OH, and pentan-1-ol is C5H11OH. Evaporation is a type of vaporization that occurs only on the surface of a liquid. For molecules of a liquid to evaporate, they must be located near the surface, be moving in the proper direction, and have sufficient kinetic energy to overcome the liquid phase intermolecular forces. Since the kinetic energy of a molecule is proportional to its temperature, evaporation occurs more quickly at higher temperatures. As the faster moving molecules escape, the remaining molecules have a lower average kinetic energy, so the temperature of the liquid decreases. Also, evaporation tends to occur more quickly on liquids with higher vapor pressure. Alcohol evaporates faster than water because water has extensive hydrogen bonding between its molecules which results in its high boiling point whereas in alcohol, amount of hydrogen bonding is smaller as compared to water. This makes the boiling point of alcohol less than water. A major factor that tells the rate of evaporation is the intermolecular forces between the molecules. The stronger the forces’ keeping the molecules in a liquid state, the more energy needs to escape. Other factors that affect the rate of evaporation include the concentration in the air since air that has a high concentration of the substance will...
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