Purpose: The purpose of this lab is to titrate an unknown solid acid (KH2PO4) with a standardized sodium hydroxide solution. After recording and plotting the data, the acid’s equivalence point will be recorded once the color changes. Using the equivalence point, the halfway point will be calculated, which is used to determine the acid’s equilibrium constant. The acid’s calculated equilibrium constant will be compared with the acid’s established pKa value. Eventually using the NaOH and the acid’s consumed moles, the equivalent mass will be determined.
Extra care was taken to not touch the plate with bare skin. Five spots were labeled on the line and each amino acid standard was spotted on the plate using a capillary tube. The standards included leucine, alanine, phenylalanine, and lysine. The final spot was an unknown mixture of three amino acids. After allowing the spots to dry, the plate was placed in the developing jar and allowed to develop.
Measure rate of CO2 produced in the upside down 250 graduated cylinder (you will see that the water levels begin to decrease from the top of the cylinder. The gas at the top of the cylinder is CO2) 14. One individual will be watching the increase of CO2 and controlling the timer, while the other will be holding the test tube and recording the increase of CO2 15. At every 15 second interval, record the volume of CO2 gas produced in the cylinder, into a table, until you have reached 180 seconds (you must perform three trials for each concentration of HCL) 16. Carefully pour out all of the HCL that was in the conical flask and thoroughly rinse CaCO3 chips and conical flask with tap water 17.
A solution to this error would have been to use more precise scales like scales that measure to 3 decimal places rather than to 1 decimal place to get a more exact value instead of a less accurate measurement. A final source of error that was made during the experiment is the concentration of the products used were low so there might have been other thing in the vinegar to add mass to the final solution. A solution to this error could have been to use a more concentrated acetic acid because the vinegar could have other products that could ruin your calculations in the end if it did not dissolve with the
E. Discussion: In order to synthesize the polymer, Nylon 6,10, we had to complete a few steps to create the chemical reaction that combined sebacoyl chloride and hexamethylenediamine. First we measured the mass of the two graduated cylinders when they were empty, and measured it again after they were filled with sebacoyl chloride and hexamethylenediamine. We did this in order to find the measurements of the reactants. When we measured the graduated cylinder when they were emptied, one weighed at 10.99 grams while the other weighed at 10.94 grams. Even though they were the same kind of cylinder, I believe that a systematic error might have caused the second cylinder’s weight to be slightly affected, causing the weight to be lowered by 0.05 grams.
Then five millilitres of sample “A” were placed in the test tube labeled “A”. This was then repeated with the next three samples. Each sample was visually observed and the colour of each was recorded. Next 20 drops of Benedict’s solution were added to each test tube and the test tubes were lowered into a hot bath at a temperature of approximately 80 degrees Celsius. All colour changes were recorded.
The retention factor for each dye was calculated. F or each of the Kool-Aid flavors, 2.0 g was weighed out from the packet and 5mL of water was mixed in with them each. mL of 0.1% NaCl solution was added to 100mL of bottled water. The six chromatography strips
Grishma Patel Chloroplast Pigments and Colored Light Absorption Summary The purpose of executing this lab was to see how different wavelengths and colors of light are absorbed by chloroplast pigments. The goal was to see the variations of light dependant reactions of photosynthesis based on different types of light. Spinach was used by grinding it with acetone and acquire the thylakoids used in the experiment. DCIP was used in this experiment as the oxidizing agent that will turn blue to clear when in contact with light. The experiment required us to test first the relationship between wavelength of light and absorbance.
The 10.00 mL graduated cylinder was refilled with deionized water and was poured into the same 500 mL plastic bottle. Using a 50 mL graduated cylinder, the remaining 480.0 mL of deionized water was added to the 500 mL plastic bottle. The lid was secured over the bottle and the contents were then shaken thoroughly. A piece of tape was placed onto the bottle with the groups names, and space for the concentration of NaOH and standard deviation to be written at the end of the experiment. After 0.1 M NaOH solution was prepared, the next step is to standardize the NaOH solution by using titration.
This test tube lacked hydrogen peroxide in order to keep the reaction from occuring. In two test tubes labeled “Substrate”, we mixed 0.2 ml of hydrogen peroxide with 0.1 ml guaiacol and 4.7 ml of distilled water. We also labeled two test tubes “enzyme” using a glass marking pen and filled them with 1.0 ml of turnip extract and 4.0 ml of distilled water. After the test tubes were prepared, we put the blank test tube into a cuvette and put it into the spectrophotometer in order to zero it out. While one group member set the spectrophotometer to zero, another mixed one enzyme test tube with one substrate tube and observed a change in it’s color.
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
To begin, one must test for monosaccharides. Glucose is necessary, and is needed to be placed into a test tube at a quantity of 5 mL. 3 mL of Benedict’s solution is then added. The test tube is then placed in a beaker of boiling water for five minutes or until the color changes. If the color changes, then it is known that monosaccharides are present in the solution.
Set the wavelength to 470 nm, this is to measure the tetraguaiacol. Set the spectrophotometer to zero by using a blank. The blank should contain 13.3 mL of distilled water, 0.2 mL of guaiacol, and 1.5 mL of enzyme extract in a clean test tube. After, transfer a portion of this mixture into a cuvette, cover the top of the cuvette with Parafilm and then place the cuvette into the spectrophotometer and set it to
First Professor Greenberg assign a labeled unknown acid solution, then we recorded the solution’s identity and bottle code. Next, we obtained an Erlenmeyer flask for the titration. Rinse it with DI water. Next we are to dispense from the buret at least mL of the designated acid into the flask. Record the initial and final volume readings on the buret in laboratory notebook data table.