Simple and Fractional Distillation of Cyclohexane and Toluene Purpose: The purpose of this experiment was to become familiar with the processes of simple and fractional distillation. In this experiment a mixture of two volatile compounds, cyclohexane and toluene, were separated with the process of distillation. Distillation relies on each compound having distinct and separate boiling points. The pure products were analyzed with gas chromatography to determine the success of the distillation. Introduction: Distillation is the process of heating a liquid until it boils, then condensing and collecting the resulting hot vapors.
By using this method of distillation a mixture is heated to a temperature at which several fractions of the compound is evaporated the distillate is then condensed and collected. Generally the component parts have boiling points that differ by as little as 20-30°C under a pressure of one atmosphere. However, cyclohexene and cyclohexanol have boiling points of 83°C and 161°C, respectively, and fractional distillation was used to separate the starting material from the desired product. The mixture is heated and boiled and the vapors produced are condensed and the distillate is collected and then tested by GC analysis. The Agilent 7890A Gas Chromatography System separates chemicals based on the ease with which they evaporate into a gas, also known as the volatility.
As it was uncapped some of the heat would have been lost to the air and as one of our assumptions was that the heat released by the reactions was used only to heat the water the value calculated will be off. The consequence of this source of error would be the measurement of a lesser final temperature and therefore the heat of reaction calculated would also be less. Another source of error could be due to the use of a white Styrofoam cup and the dissolving of white sodium hydroxide pellets. It would be easy to miss if the reaction had yet to fully take place meaning the final temperature recorded would be lower and heat of reaction calculated would be lower. A final possible source of error could be that not a precisely even amount of HCl and NaOH were used for the neutralization reactions in part two and three.
The half reactions for this system are: Oxidation of 〖Fe〗^(2+): 〖Fe〗^(2+)→ 〖Fe〗^(3+)+1e^- Reduction of 〖MnO〗_4^-: 〖MnO〗_4^-+8H_3 O^++5e^-→ 〖Mn〗^(2+)+12H_2 O Which produces the following overall equation: 〖MnO〗_4^-+8H_3 O^++5〖Fe〗^(2+)→5〖Fe〗^(3+)+〖Mn〗^(2+)+12H_2 O Equilibrium is initially obtained at a very slow rate, therefore the titration is carried out in the presence of excess sulphuric acid (H_2 〖SO〗_4) at a high temperature; in order to drastically increase the rate at which equilibrium is attained. Potassium permanganate acts as its own satisfactory indicator since the reagent 〖MnO〗_4^- anion appears to be an intense purple colour while the product 〖Mn〗^(2+) cation has a colourless appearance. However, the end point must be read quickly as the permanganate end point gradually fades due to the 〖MnO〗_4^- reacting with the 〖Mn〗^(2+) that was formed during the titration. When performing the titration, one must be cautious as side reactions can occur and these side reactions must be prevented using appropriate chemical measures. If an insufficient amount of acid was
n (3) Solutions of aqueous sodium hydroxide and hydrochloric acid react to form water and aqueous sodium chloride. co NaOH(s) → Na+(aq) + OH–(aq) ∆H1 = ? Chemistry with Vernier py In this experiment, you will use a Styrofoam-cup calorimeter to measure the heat released by three reactions. One of the reactions is the same as the combination of the other two reactions. Therefore, according to Hess’s law, the heat of reaction of the one reaction should be equal to the sum of the heats of reaction for the other two.
The reddish color of bromine is discharged upon addition to an alkene as the bromine reacts, making this reaction a useful qualitative test for unsaturation when the reaction has gone to completion. The mixture will still be stirred for thirty minutes, regardless of the change in color; since there is a production of an intermediate, the reaction goes by an SN2 mechanism and is dictated by second order kinetics. The dissipation of color will only indicate that the bromine in solution has reacted and not necessarily that the rest of the solution has gone to completion. While this solution is being stirred, the molecules of the mixture are coming in contact and the bromination reaction is occurring. The electrons of the polarizable pi bond in the alkene E-stilbene acts as a nucleophile, a chemical species that donates an electron pair, and attacks one of the bromines in the dibromide molecule, which then causes the sigma bond to break as well.
Energetics Aim: To measure the energy released from the complete combustion of a known mass of alcohol or paraffin wax, to heat water. Hypothesis: The combustion of alcohols is exothermic. In this experiment the energy is released from burning a known mass of alcohol in order to heat a known amount of water. A comparison of various alcohols and paraffin wax (methanol, ethanol, propanol, butanol, octanol and candle) as fuels can be made by calculating the quantity of energy transferred to the water. In this experiment, the amount of energy (heat) involved in a chemical change will be determined.
The products of a combustion reaction are carbon dioxide and water. I also found out that it takes skill to light a match and that it’s difficult to keep gas where you want it to be without a sealed container. There are many sources of error. The first source of error was that if you blow on the candle too hard, the wax vapor blows away and the flame doesn’t jump. The next source of error is that if you don’t put in the limewater and stopper quickly enough, the carbon dioxide escapes and the water won’t turn chalky.
There was a low efficiency rate for this experiment; energy was most likely wasted into the surrounding environment when the burner was alight. Possible ways to improve this experiment would be to possibly do the experiment in a more enclosed space, so as to disallow any heat escaping into the surrounding atmosphere. A fume cupboard would be suitable (when it is not turned on) as there is less movement in the air to move the energy from its intended target. The thermal energy was not only going into the water, but the can of the calorimeter became hot too, meaning that the thermal energy was transferred into the metal surrounding the water, and not just the
The smaller amount will ‘limit” how much the reactant can produce. A percent yield in a chemical equation is used because chemical reactions do not predict amount of a substance. The percent yield is usually determined by the mass that is in the chemical reaction. A percentage will be produced from using the formula; This percentage is the calculation of your success of producing a product compared to the total amount of a product that can be produced. The familiar volcano experiment that we all know, mixing baking soda and vinegar, is used to create a bubbly reaction.