Distillation Distillation is used to remove impurities from a mixture – one component of which must be a liquid. Boiling points are utilized in determining the identity of the unknowns. Types of distillation include
Nora Azmani IB3G Chemistry HL Dr. Petersen Date of submission: 01/12/2014 Comparing the Enthalpy Changes of Combustion of Ethanol (CH3CH2OH) and Butanol(CH3CH2CH2CH2OH) in order to determine which one of them that is the more efficient as a fuel. Objective The purpose of this lab is to determine the fuel efficiency of the two alcohols Ethanol and Butanol, by comparing their respective enthalpy changes. The most efficient fuel will be the one with the highest enthalpy change of combustion. The enthalpy changes will be determined by examining the effect the alcohols have on the water’s temperature change. Balanced Equations for the Combustion reactions of Ethanol and Butanol: Ethanol combustion: CH3CH2OH(l)+ 3O2 (g) --> 2 CO2 (g) + 3
Data Table 1. Comparing the temperature of each liquid every 30 seconds Time (sec) Temperature of the water (°C) Temperature of the isopropyl alcohol (°C) Temperature of the ethyl alcohol (°C) 30 34.6 43.1 37.0 60 45.3 63.8 55.1 90 54.8 80.2 74.3 120 64.0 80.5 76.8 150 72.4 80.5 76.8 180 79.7 80.5 76.7 210 86.8 80.4 76.6 240 93.4 80.3 76.4 270 97.7 80.2 76.4 300 98.5 80.2 76.3 330 98.8 80.2 76.2 360 98.0 N/A 76.2 390 98.0 N/A 76.1 420 97.9 N/A 76.1 450 98.2 N/A 76.1 480 97.9 N/A 76.1 510 97.7 N/A 76.1 540 97.6 N/A 76.1 570 97.5 N/A 76.1 600 97.5 N/A 76.2 Table 2. Boiling points of the three different liquids Liquid Boiling Point (°C) Water 98.9 Isopropyl Alcohol 80.6 Ethyl Alcohol 76.9 Table 3. Polarities of the three different liquids Liquid Polarity
This distillation is performed in one step. Furthermore, fractional distillation consists of a fractionating column in addition to the other apparatus. Fractional distillation is used when two compounds' boiling point differs by less than 40 C so that a better separation occurs. Figure 5 is a graph of
This is due to the boiling points of the two compounds are too close for an effective simple distillation. A simple distillation only works when the boiling points of the two compounds are separated by at least 50 °C (CITATION). Meanwhile, the boiling points of the compounds of the mixtures are 82.3 °C for 2-pronanol and 117 °C for 1-butanol (National Center for Biotechnology Information). As well, while fractional distillation is more difficult due to the added fractionating column and insulation, it allows for better separation and condensation of the individual compounds. This ensures that only the compound with the lower boiling point is completely condensed before the compound with the higher boiling point begins to condense.
The drying agent was discarded when the mixture was filtered. The dichloromethane in the mixture was evaporate when the mixture was heated on a hotplate of 120 degrees C. It was heated until it stopped bubbling and a small oil layer remained. Petroleum ether (15 mL) was added, mixed, and cool in an ice bath. The product was vacuum filtrated, keeping the precipitate. The precipitate was further dried by utilizing a drying
This is because the the lower member is a very polar molecule therefore the very polar alcohol/carboxylic acid would react with the very polar water molecules. In this experiment, 1-butanol is slightly soluble in water but ethanoic acid is very soluble in water. The reason why the higher members which is 1-butanol in this case have non-polar and polar bond and they are only slightly soluble in water is because the non-polar 1-butanol is dominant to the very polar water molecule, hence making it a non-polar
The chromatogram confirmed the identity of the lower boiling point solvent as acetone, and the higher boiling point solvent as toluene. The unknowns were correctly identified due to the clear presence of two plateaus in the experimental data. The hot plate was not turned on too high or too low to not obtain one of the three samples, and a sufficient number of values were taken in each part of the distillation before the mixture evaporated away to obtain approximately accurate data for boiling points. The ratio calculated for the volume of solvents in the mixture was .506/.488, where the composition of the mixture was 50.6% acetone, and 48.8% toluene. These two values did not add up to 100% because the GC also recorded some impurities,
• The solution was then heated gently until the solution begins to distil and that is when the first temperature was recorded. • Samples were collected every (3 mL) using sample vials and the temperature was recorded during each fraction. • The distillation was stopped when (3 mL) of the solution was left in the distillation flask because letting it boil
Fractional distillation is a separation technique used to separate two liquids with different boiling points and keep the liquid. To do this, we set it up just like the distillation lab with the 10-15mL in the test tube over the fire and the tube leading the the test tube in the beaker. The first time you go through, the same test tube is left in the whole time but you must record the temperature around every 10-15 seconds using your labquest. You then find two places where the temperature is consistent for a few seconds, this is your plateau. The second time you go through, change out the test tubes as soon as you get to your first plateau, this liquid is liquid one.