For every 20 drops of solution you will add 0.1g of zinc to the new test tube. Repeat steps 3 and four until the solution is clear. If there ever exists too little of the solution to get enough drops, add up to 1mL of distilled water to the solution. 4. Once the solution is clear, retrieve at least ten drops of the solution and place them in a new test tube.
After that, dissolve the sample in 2 mL of deionized water and shake the test tube for 1 to 1 ½ minutes to dissolve the solid. Place another dry test tube in a 50mL beaker and weigh it. Find a bottle of barium iodide and record the name and molar mass. Then, weight out either anhydrous barium iodide or barium iodide dehydrate into this test tube and dissolve is it in 2 mL of deionized water. Pour the contents of one of the test tubes into the other and a reaction should occur and you should see a white precipitate of barium sulfate form.
Materials and Methods Part 1 For the cation elimination test first 10 drops of potassium, iron (III), zinc (II), copper (II), and cobalt (II) were added to 5 centrifuge tubes and the color was recorded. Then for the metal hydroxide test, 6 M NaOH was added drop wise till a precipitate was formed. Each solution except potassium formed a precipitate, so then 10 additional drops of NaOH were added to the remaining solutions. Tubes were cleaned with distilled water and 6 M HCL. Next was the ammonia test 10 drops of each metal solution were added to new centrifuge tubes and 15 M NH4OH was added until the solution changed color or a precipitate was formed.
William Flores-Paz Monitoring Acid-Base Titrations with a pH meter October 30, 2013 Introduction The purpose of this experiment was to record the volume of HCl and acetic acid with a NaOH with a known molarity. This data would allow us to create a graph so we could compare the two titration curves. We would then use these curves to calculate the unknown molarities. HCl + NaOH >H2O + NaCl This equation shows the relationship between the acid and the base then the reaction goes forward and they are titrated creating salt and water. This particular reaction is a strong acid and a strong base which means that when the reaction reaches the equivalence point, the moles of the acid and the base are equal and the solution is neutral so the pH should be around 7.0 depending on the final volume of each solution.
Procedure: 1. Fill a beaker two-thirds full of water and add approximately 20 drops of IKI. Write down the solution's color and record the mass of the bag. 2. Do an initial Benedict's test on the 15% glucose/1% starch and the beaker solutions for glucose by putting some of the solution and a roughly equal amount of blue Benedict's solution in a test tube, placing the test tube in boiling water for 90 seconds, and observing whether or not the solution changes color from blue.
The first test tube will be control, the second will be substrate and indicator dye, the third will be dilute extract, the fourth will be the same contents as the second, the fifth will be medium concentration of extract, the sixth will be the same contents as the second, and the seventh will be concentrated extract. 3) Add stock solutions to each tube using the corresponding graduated 5 ml pipette or dispensing device. 4) Adjust the spectrometer to zero absorbance at 500nm. Pour contents of test tube 1 into a cuvette. ) Make sure to keep time, read the spectrometer, and record the data.
Why is this necessary? Obtain an appropriate amount of 5.00 M NaCl and fill your 25 mL buret. Pipet a 20.00 mL aliquot of 0.100 M acetic acid solution into a 100 mL beaker, add a magnetic stirring bar, and then set up the titration apparatus as indicated in Figure 1. Record the initial pH and then begin titrating. You will titrate in 0.25 mL intervals for the first 2 ml and then in 1 mL intervals until a total of 6 mL of 5.00 M NaCl has been delivered.
Then allow test tubes to remain at various temperatures for 5minutes, remove the test tubes and add 2cm of catechol and shake to allow them mix. Finally the record the results. As temperature increases the rate of enzyme activity increases until it reaches its optimum point, in this graph the optimum point is 20-60 oC, This is the point where enzymes works best if temperature increases above the optimum point the rate of enzyme activity decreases until the point where the enzymes are denatured, the color intensity gets darker as temperature increases. Effects of pH on Enzyme Activity pH directly has an effect on the active site, and is therefore important to have proper pH,however high or lower ph. affect the enzyme activity, to get enzymes working there should be proper ph.
Suggest two reasons for this change. Task 2 Press back but not clear and change the number of chips to 10 but leave the acid concentration at 1.0 mol/dm3 . Click start and take readings approximately every 3 seconds (by clicking the take readings button) until the mass reaches 0.0 g. Stop the reaction immediately. Plot these results on the same grid as the results of your first experiment. How does the rate of reaction in Task 2 compare with the rate in Task 1?
Kobs is the slope on the graph plotting Vol of NaaS2O3 against time. Specific hydrogen ion catalysis Kobs = KH+[H+] This is used when a strong acid is being used in the reaction as it acid fully dissociated and there is no A- value. This is the equation used for reactions (i), (ii) and (iv) as they used HCl as the acid. General acid catalysis Kobs = KH+[H+] + KHA[HA]. This is used when a weak acid is being used in the reaction as it acid does not fully dissociated and there is an A- value.