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University Degree: Chemistry

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  1. Determination of the density of an unknown liquid

    We will use distilled water, for which temperature dependent values of density rH2O are shown in Table 1. The pycnometer is a glass flask with a close-fitting ground glass stopper with a capillary hole through it. This fine hole releases a spare liquid after closing a top-filled pycnometer and allows for obtaining a given volume of measured and/or working liquid with a high accuracy. 1. Let M to be mass of empty pycnometer 2. Let Mw to be mass of pycnometer with distilled water inside 3. Let d be the density of distilled water at temperature T 4.

    • Word count: 1683
  2. SN1 Reaction: Preparation of Cyclohexyl Chloride

    44 % Qualitative Test Results Observation Chromic Acid + Yellow color was still observed but after some time dark greenish precipitate began to form in the bottom of the test tube, although the yellow color was still present, possibly due to low amounts of alcohol in the mixture Silver Nitrate + Formation of tiny white solids when silver nitrate was added DISCUSSION Experiment 8 examined SN1 reactions which are reactions that synthesize alcohols where the rate-determining step in uni-molecular. This reaction contains a leaving group which leaves resulting in a carbocation that is immediately attached by a nucleophile that is commonly a weak base.

    • Word count: 571
  3. Copper Penny Lab Report - measuring density.

    The new displacement of water was recorded to tenths of a milliliter. 6. Again step 1 was repeated using a new set of 20 pennies minted between 1962 and 1982. 7. The set of 20 pennies were added to the graduated cylinder containing 20 mL of distilled water and 15 pennies, now totaling 35 pennies. The displacement of water was recorded to tenths of a milliliter. 8. The water was poured out of the graduated cylinder and the pennies were carefully taken out and dried with a paper towel.

    • Word count: 1407
  4. Forensic Chemistry - Ion Selective Electrode. The objective of experiment is to determine the chloride and nitrate (toxic anions) in samples from the calibration curve

    All in all, the experiment was a success as all the objectives were met. 1. Objective of Experiment The objective of experiment is to determine the chloride and nitrate (toxic anions) in water by reading from the calibration curve which involves the calculation and weighing of NaCl and NaNO3 for the preparation of the stock solutions. 2. Introduction Introduction of Ion Selective Electrodes The term ?ion selective electrode? applies to a range of membrane electrodes which respond selectivity towards one (or several species)

    • Word count: 8853
  5. The objectives of this experiment are to synthesis 1-bromobutane from n-butanol under reflux setup via SN2 mechanism

    The order of reactivity of alkyl halide is CH3X>1o>2o>3o. Since the substrate in this reaction is n-butanol, a primary substrate, it will favor SN2 reaction instead of SN1 reaction. Reflux Just about 80% of the reactions in organic lab involve a step called refluxing. You use a reaction solvent to keep materials dissolved and at a constant temperature by boiling the solvent, condensing it, and returning it to the flask. To execute a reflux, 1. Place the reagents in a round-bottomed flask. The flask should be large enough to hold both the reagents and enough solvent to dissolve them, without being much more than half full.

    • Word count: 3463
  6. The two central objectives of this experiment are the production of Aspirin from esterification of salicylic acid with excess acetic anhydride and obtaining it in a purer state by recrystallisation

    are formed. From this experiment, the percentage yield of ASA is around 49%, the melting point of ASA falls in the rage of 137.9-140.5 0 C. The appearance of ASA (Fig. 1) is an odourless, white, needle-shaped and shiny solid. In conclusion, experiment is a success, despite having low percentage yield. Figure 1: Recrystallised aspirin. 1 . Objective of Experiment The two central objectives of this experiment are the production of Aspirin from esterification of salicylic acid with excess acetic anhydride and obtaining it in a purer state by recrystallisation.

    • Word count: 3360
  7. The aims of this experiment are to measure the heat of decomposition of hydrogen peroxide the heat capacity of calorimeter and calculate the enthalpy of decomposition of hydrogen.

    Enthalpy change is often called a heat of reaction because it is measure of the heat flow into or out of a system at constant pressure. If the products have more enthalpy those reactants, then heat has flowed into the system from surrounding and ?H has a positive sign. Such reactions are said to be endothermic (endo means ?within? so heat flows in). If the products have less enthalpy than reactants, then heat has flowed from the system to the surroundings and ?H has a negative sign.

    • Word count: 5408
  8. The objective of this experiment is to determine how a buffer system resists large changes in pH due to addition of strong acids.

    From the results we have obtained, we notice that buffer with higher concentration has greater buffer capacity as greater volume of acid is needed to swift the pH by the same units and getting a stepper gradient(greater change in pH) for curve compared to a less concentrated buffer solution. Moreover, deionised water has displayed almost negligible buffer capacity as it is poorly dissociated and needed a tiny amount of HCl to change its pH drastically. Conclusively, we state that the greater the concentration of both the weak conjugate base and acid the stronger its buffer capacity.

    • Word count: 4935
  9. Ionic Reactions Experiment.

    3. Set up a 96 well plate and arranged all chemicals needed to perform experiment. I then constructed a table to record all observations and possible precipitates viewed. 4. I placed two drops of cobalt (II) nitrate into 7 wells under row A in the well plate. (Two drops in each of the seven wells) 5. I then followed the same procedure as with the cobalt (II) nitrate with 4 more substances in 4 different rows. 2 drops copper (II) nitrate in seven wells of row B, iron (III) nitrate in row C, barium nitrate in row D, and nickel (II)

    • Word count: 1584
  10. Steam Distillation of (S)-(+)-Carvone from Caraway Seeds and (R)-(- )-Carvone from Spearmint Leaves. Analysis of Products by Infrared Spectroscope and TLC

    The mole fraction can be determined by dividing the number of moles of X by the sum of the number of moles of all components: Nx= (nX)/(nX + nY + nZ + ?). When there are two or more volatile components then the total vapor pressure is equal to the sum of the partial vapor pressures: Ptotal = Px + Py + Pz +? otherwise known as Dalton?s law only it includes more than one component. Enantiomers are compounds that have the same molecular formula and structure, but they differ in the placement of molecules around an asymmetrical carbon atom called a stereocenter.

    • Word count: 4239
  11. Separation of Liquids by Simple Distillation and Analysis by Gas Chromatography

    When performing simple distillation, three fractions are collected. First is when the temperature remains close 77° C; second, when a rapid increase in temperature is observed and third, when the temperature remains close to 126° C. These fractions are then used for gas chromatography. Ethyl Acetate Butyl Acetate Figure 1: Structures of Ethyl Acetate and Butyl Acetate Distillation is a laboratory method to separate and purify a mixture of compounds. There are many kinds of distillation techniques such that simple distillation and fractional distillation. However, this lab is based on simple distillation following Gas – Liquid Chromatography (GLC).

    • Word count: 3066
  12. Inorganic

    Both compounds are ionic conductors and can transfer voltage through their constituent ions. The purpose of the experiment performed over two days spread out over two weeks, were multiple. One, was the formation of the previously mentioned compounds, Cu2HgI4 and Ag2HgI4. The second, was to measure the purity of the compounds through measuring the thermochromatic temperature change, leaving the final objective to measure the ionic conductivity of Ag2HgI4. EXPERIMENTAL For Cu2HgI4, 0.164 grams of KI (dissolved in approximately 5 mL of H2O), 0.229 grams of HgI2 were added to a 25 mL Erlenmeyer flask.

    • Word count: 1565
  13. Objective: To isolate benzoic acid from the toluene-benzoic acid mixture by liquid-liquid extraction and purify the benzoic acid by recrystallization.

    Melting points determination is able to find out the physical properties of a compound and also the purity. The narrow a melting point range, the pure compound is obtained. Procedures: Extraction of benzoic acid 30 mL of the stock toluene-benzoic acid mixture was transferred into a separatory funnel and the exact volume of the solution was recorded. 15 mL of 10% aqueous sodium hydroxide was added into the separatory funnel and the lower aqueous layer was collected into a conical flask. A small amount of the lower layer (<0.5 mL) was allowed to remain in the separatory funnel.

    • Word count: 1933
  14. Experiment - determination of the valency of magnesium

    The watch glass was invert and placed over the magnesium. 4. The beaker was carefully filled with (tap) water until the level was approximately 0.5-1.0cm above the end of the funnel stem. The burette was completely filled with 0.5MHCl. The beaker was inverted and placed in the water in the beaker, and the end of the burette was placed over the stem of the funnel, no air enters was ensured and clamp it into position. 5. The excess of water was removed with a pipette until the level was just above the stem of the funnel. 6. About 100cm3 of 0.5M HCl was added to the beaker, a glass stirring rod was used to ensure complete mixing such that the HCl reached the magnesium.

    • Word count: 1244
  15. The purpose of this experiment was to determine the equilibrium constant of the reaction between iron (III) chloride (FeCl3) and potassium thiocyanate (KSCN) through the use of spectrophotometry.

    In this state, the concentrations of the products and reactants are constant or stable. When in equilibrium, there is no net change in the amounts of the products and reactants if not disturbed by any means. For this reason, the proportion of the concentrations of the products over the reactants raised to their respective coefficients is also constant. This proportionality is known as the equilibrium constant, Keq. For the reaction in this experiment, Fe(aq)3++SCN(aq)-?FeSCN(aq)2+ [1] The equilibrium expression is, Keq= [FeSCN2+]eq[Fe3+]eq[SCN-]eq [2] The product, FeSCN2+, is a blood red complex that absorbs visible light.

    • Word count: 2075
  16. CALORIMETRY EXPERIMENT - In this experiment the students were tasked to experimentally verify the Hrxn of different reactions

    111.6 125.6 2 2.0 -279 279 139.5 6 1 2.5 -279 279 111.6 125..6 2 2.0 -279 279 139.5 7 1 1.7 -279 279 164.1 151.8 2 2.0 -279 279 139.5 8 1 3.5 -279 279 79.7 73.05 2 4.2 -279 279 66.4 9 1 2.5 -279 279 111.6 125.6 2 2.0 -279 279 139.5 10 1 3.0 -279 279 93 93.0 2 3.0 -279 279 93 The data gathered by the students regarding the calibration of their respective calorimeters are shown in Table 1.

    • Word count: 1638
  17. EXPERIMENTAL DESIGN: Measurement of Density and Determination of Partial Molar Volume, and the Effects of Concentrations to Surface Tension and Viscosity of Cyclohexane-Benzene Binary System

    It is also hypothesized that there is no significant difference between the changes in concentration and the surface tension of the liquid. Furthermore, it is to prove that the data of the partial molar volume of the system is acceptable that there is a significant difference between the observed and expected value of the partial molar volumes of the system. The study aims to create a partial molar volume versus the mole fraction of benzene graph, to determine the partial molar volume of benzene-cyclohexane system at different concentrations using density measurement, and to compare it to a standard value predetermined by another experimental report.

    • Word count: 4337

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