chem
...and 4 with the HCl buret, using HCl solution to rinse and fill it. 6. For trial 1 record the initial reading of each buret, estimating to the nearest 0.01mL in the Data Table. For consistent results, have your eyes level with the top of the liquid each time your read the buret. Always read the scale at the bottom of the meniscus. 7. Draw off about 10mL of NaOH solution into an Erlenmeyer flask. Add some distilled water to increase the volume. Add one or two drops of phenolphthalein solution as an indicator. 8. Begin the titration by slowly adding the HCl from the buret to the Erlenmeyer flask while mixing the solution by swirling it as show in Figure B. Stop frequently and wash down the inside surface of the flask using your wash bottle. 9. When the pink color of the solution begins to disappear at the point of contact with the acid, add the acid drop by drop, swirling the flask gently after each addition. When the last drop added cause the color to disappear from the whole solution and the color does not reappear, stop the titration. A whit sheet of paper under the Erlenmeyer flask makes it easier to detect the color change. 10. Add NaOH solution dropwise just until the pink color returns. Add HCl again, dropwise, until the color just disappears. Go back and forth over the end point several times until one drop of the basic solution just brings out a faint pink color. Read the burets to the nearest .01mL, and record these final readings in your data table. 11. Discard the liquid in the flask, rinse thoroughly with distilled water, and run a second and third trial. 12. Record the know concentration of the standard HCl solution in the data table. 13. Clean all apparatus and your lab station. Return all the equipment to its proper place. Dispose of chemicals and solutions in the containers designated by your teacher. Do not pour any chemicals down the drain or in the trash unless your teacher directs you to do so. Wash your hands thoroughly before you leave the lab and after all work is finished. Data/Observations: HCL NaOH Trial Initial Volume (mL) Final Volume Initial Volume Final Volume 1 5.51mL 8.59mL 5.59mL 19.59mL 2 8.59mL 10.58mL 8.24mL 20.47mL 3 7.35mL 14.73mL 10.11mL 43.63mL Molarity of HCl 0.1 M HCl Calculations: 1) Trial 1: Volume of HCl= 8.59mL – 5.51mL = 3.08mL Trial 2: Volume of HCL= 10.58mL – 8.59mL = 1.99mL Trial 3: Volume of HCL= 14.73mL – 7.35mL = 7.38mL 2) Trial 1: Volume of NaOH = 19.59mL – 5.59mL = 14mL Trial 2: Volume of NaOH = 20.47mL – 8.24mL = 12.23mL Trial 3: Volume of NaOH = 43.63mL – 10.11mL = 33.52mL 3) Converting formula of mL à L : _____mL x 1_L = ______L 1000mL Trial 1: Moles of acid = 0.1 M x 0.00308L = 3.08 x 10 mol HCl Trial 2: Moles of acid = 0.1 M x 0.00199L = 1.99 x 10 mol HCl Trial 3: Moles of acid = 0.1 M x 0.00738L = 7.38 x...