Data: There were two separate sections of data collected: the Preparation Table(Table 1) and the Titration Table(Table 2). This was due to the initial production of the weight buret- the sodium thiosulfate solution and the dropping bottle- represented in Table 1 and the trials that occurred separately(Table 2). The initial mass of the solid sodium thiosulfate pentahydrate was 0.21 grams. Once the ten milliliters of water was added, the mass of the sodium thiosulfate solution as 9.70 grams(Table 1). In Table 2, the initial mass of the weight buret in trial one was 15.23 grams, the final mass of the buret was 14.14 grams.
The cup was then covered and the temperature probe inserted. While the probe was collecting a few initial temperature readings for the solution, 50mL 2M NH4Cl was prepared but not added to the solution. After 3-4 readings were collected, the 2M NH4Cl was added to the solution. The lid was quickly replaced, preventing heat from escaping and not being recorded by the temperature probe. The cup was swirled until the temperature reached a peak and
In the lab, “Properties of Hydrates,” the purpose was to compare the properties of several well observable hydrates and to determine if dehydration is a reversible or irreversible change. The lab consisted of attaining a pea-size sample of each compound, burning it over a bunsen burner, and comparing the starting mass and the mass lost after the combustion. These results are important to be able to identify a variety of different chemicals that contain water molecules as part of their crystalline structure. Some can be removed by heating (resulting in evaporation) and some remain mostly unchanged. In this lab the answer will be found.
Methods: Weight a clean, dry, porcelain evaporating dish on the electric balance and record this mass on an appropriate data table. If the crucible needs to be washed before use, then heat the crucible in the Bunsen burner flame for a few minutes and remove any residual water. Then allow it to cool before continuing. Fill the crucible about 1 gram with the hydrated salt and reweight. Assemble the ring stand, ring, clay triangle, and Bunsen burner
The items that were massed were the evaporating dish, watch glass, and NaCO3. The materials were massed once before and once after being heated in the drying oven. The mass of the evaporating Dish before was 46.57 g; while after being heating was 60.15 g. The mass of the watch glass before was 57.97 g and after was 48.75g. There were two masses taken for the substance NaHCO3- one with the evaporating dish and one without, subtracted out after the lab was concluded. The mass of the substance with the dish was 48.79 g before and 62.33 g after; meanwhile, the mass of the substance without the dish was 2.22 g before and 2.18 g after.
* In the above RB, a calculated amount of 1.2 equivalent amount of PTSH was added during continous stirring. * To the RB a condenser was attached and it was put on refluxing for a time period of 18 hours at a temperature of 80 degrees in an oil bath. * Post refluxing, the condenser was removed and it was left undisturbed for 1 day and then cooled to a temperature of -20 degrees by keeping in the freezer for setting of hydrazone crystals. * Once the crystals were formed, the supernatant was decanted and the crystals were transferred to a beaker where they were washed with cold methanol and then dried. * These dried hydrazone crystals were used in the subsequent steps.
III. Prepare solutions of solutions of sodium chloride in distilled water consisting of the following percentages by weight: 5%, 10%, 15%, 20%, and 25%. Prepare 25mL of each solution. You do not have to prepare a 100g of each to be able to use the percentage composition. The weight determination of the solute should be to the nearest milligram.
15. Dry the evaporating dish. Wait for the dish to cool off then weigh it with the product. Mass of copper wire .2654g Sodium Hydroxide 45mL Sulfuric Acid 25mL Zinc 3.0g Hydrochloric acid 15mL Methanol 10mL Acetone 10mL Calculations In order to find the percent recovered, 100% was multiplied by .2285g divided by .2654g = .086. Mass of copper (beginning) .2654g Mass of copper recovered .2285g Color of Copper oxide Black Conclusions The first attempt of this experiment was unsuccessful because the solution did not turn black after putting the nitric acid into the copper wire.
The washings are filtered off into a 100 mL measuring flask; after cooling distilled water is added until the mark is reached (stock solution). In proportion to the expected chloride content aliquot part of this solution, which should preferably contain 50 mg – 100 mg NaCl, taken off, distilled water being added to obtain a quantity of approximately 100 mL. Subsequently 5 mL ferric alum solution, 20 mL 0.1 N AgNO3 solution and 5 mL – 10 mL ether or 1 mL nitrobenzene are added; titration is carried out by means of an ammonium thiocyanate solution 0.1 N, until the red colouring remains after
The ion exchange capacity is measured by the chemical titration [Hasimi A, Stavropoulou A, Papadokostaki KG, Sanopoulou M. Euro Polym J (2008) 4098-107]. In order to measure the IEC values, the dry samples were soaked in 1M aqueous NaCl solution at room temperature for 24 hours to exchange of proton by sodium ions. The ion-exchanged NaCl solution was back titrated with 0.1M NaOH solution using phenolphthalein as an indicator. The protonic conductivity measurements were made through via Nyquist plot using N4L PSM 1735 series LCZ meter with amplitude of 10 mV from 1 Hz to 1 MHz The proton conductivity values are calculated
Then, the pipet was rinsed with distilled water. The bulbs were then attached to the pipette; filling and dispensing water were practiced using both bulbs. Furthermore, the 250-mL beaker was weighed, and its mass was recorded. After that, the Erlenmeyer flask was filled with 100 mL of distilled water. The temperature was recorded.
Part C: Change the amount of the substrate First, the blank was prepared according to table 2 without the enzyme addition. The enzyme was added later after the blank was measured by the spectrophotometer. Table 2: The amount of Sodium Phosphate Buffer pH 7.0, L-Dopa, and enzyme needed in each cuvette. Cuvette 1 Cuvette 2 Cuvette 3 Cuvette 4 Cuvette 5 Sodium Phosphate Buffer PH 7.0 (mL) 2.40 2.20 1.80 1.60 1.10 L- Dopa (mL) 0.20 0.40 0.80 1.00 1.50 Enzyme (mL) 0.40 0.40 0.40 0.40 0.40 For example, to prepare the cuvette 1, 2.40 mL of buffer pH 7.0 was measured by the micropipette P-1000, and was added into cuvette labeled #1 for the second set of cuvette. Next, 0.20 mL of L-dopa was measured by the micropipette P-1000 and was added into
While swirling the phosphoric acid solution in the Erlenmeyer flask, the sodium hydroxide solution was added to it a few drops at a time using a disposable plastic pipette. The After all the sodium hydroxide was transferred, the flask was rinsed with 2 mL of deionized water and added to the flask with the reaction mixture and swirled for an additional minute. A clean, dry evaporating dish with a watch glass was then weighed and recorded to 0.001 g. The reaction mixture was then transferred to the evaporating dish. The flask was then rinsed with 2 mL of deionized water and added to the evaporating dish containing the reaction mixture.
In this lab a mole was used to determine the measurements of all substances. A mole is a unit of measurement that follows the rule of ; 1.00 mole = molar mass = 6.02 x 10^23 atoms/ ions/ molecules / formula units = 22.4 L of any gas at standard temperature and pressure. That formula was used to determine the mass of the anhydrated substance. A anhydrate is a substance with water heated out of it. The purpose of this lab was to determine how many moles of water are
32 100 μL of afore-prepared sample solution and the mixed reference standard were diluted 100 times with ethyl acetate. 50 μL of these dilution solutions were separated on the TLC plate coated with SNISG. The plate was developed with petroleum ether: ethyl acetate (4:1) and the movement of solvent was usually controlled at 1 cm from the upper edge. After completion, the plate was dried until no solvent smell remained. It was sprayed with an ethanol solution containing 10% sulfuric acid, and heated at an infra-red drier until obvious color came up, as shown in Fig.2 (B.ab).