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Unformatted text preview: 1-1 Ch. 1Determining the % Volume of Alcohol in WineObjectives To determine the alcohol content of wine and compare to the bottle claim To measure the density of the distillate alcohol To learn a technique called distillation to separate liquids by their boiling points To practice good lab skills that will be used throughout the remainder of the semester To provide an introduction to Excel spreadsheets and data manipulation IntroductionMany companies are interested in evaluating their products or consumer goods by quantitative analysisin order to ensure that these products contain the correct amounts of substances written on the label. Quantitative analysis is a process used by analytical chemists to provide data about the quantitiesor relative proportionsof substances present in a mixture. By contrast, analytical chemists may also be interested in collecting data by qualitative analysis; this process obtains data about the identityof a substance rather than how much of that substance is present. Wine is an alcoholic drink made by the fermentation of grapes after the addition of yeast. The byproduct from this fermentation reaction is the active ingredient in wine, called alcohol (specifically, ethanol or ethyl alcohol which can also abbreviated as EtOH). Wine is a mixture of predominantly water, ethanol, sugar, and other added flavor ingredients. Wine usually contains between 7 15% alcohol (average is 11%). In this experiment, you will be analyzing wine by quantitative analysisto determine the amountof alcohol in wine and compare it to the label percentage. You will be using a technique called distillationto separate the liquid alcohol (boiling point of EtOH = 78 oC) from the liquid water (H2O boiling point = 100 oC) due to their differing boiling points. Ethanol is a clear, colorless liquid at ambient temperature. It has a lower boiling point than water and will distill at a lower temperature than water. Distillationis a process of vaporizing a liquid and condensing the vapor (called the distillate) into another container. To do Chapter One1-2 this, heat is applied to a liquid mixture to promote the liquid of interest into the gas phase (vapor); the vapor then condenses in another container when the vapor is cooled through a cold-water condenser. Distillation is an ancient technique that is still frequently used today to purify or separate compounds; additionally, it is used to determine the boiling points of new or unknown substances. For a given amount of applied heat, substances that have lower boiling points will typically boil (become gas) sooner than substances that have higher boiling points; hence, components with lower boiling points will distill before substances with higher boiling points. Figure 1 shows a diagram of a distillation apparatus. Figure 1 shows a diagram of a distillation apparatus....
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- Fall '11