2/29/24, 7:25 PM Culminating assignment: Titration lab report Throughout this course you completed a number of lab activity tasks that allowed you to draw on knowledge of chemistry, build on

laboratory skills, reflect on your learning, and make connections between your new learning and your own experiences. Now that you have reached the end of the course, this culminating activity will require you to visit all the skills you built during the lab activities and write a full lab report. Your lab report must include: • Title page (1 mark) Purpose (1 mark) • Materials (2 marks) • Procedure (4 marks) • Results (10 marks) • Analysis (15 marks) • Conclusion (1 mark) • References (1 mark) Culminating assignment: Titration lab report You have practiced how to complete each section of this lab report throughout the course. You may choose to reference the Formal lab report write-up (../locker_docs/sch3u_01.01.05.html?ou=24327639) as a guide to format your lab report. Acid-base titration lab Introduction A titration is an analytical process used to determine the volume and concentration of a solution needed to react with a given amount of another substance. When completing a titration, the solution of a known concentration is called the standard solution (or titrant). The solution of an unknown concentration is known as the analyte. In this procedure, a standard solution will be used to react with a measured volume of the analyte to find the unknown concentration. In this experiment, you will determine the concentration of an acid solution through a neutralization reaction. A neutralization reaction is when an acid and base react to product a salt and water. https://course.ilc.tvo.org//content/enforced/24327639-SCH3U-EN-02-03-ON-(1-D-0823)/course_content/assets/locker_docs/sch3u_01.01.04.html?ou=... 1/5 Culminating assignment: Titration lab report The titration proceeds until the number of moles of the acid (HT) is equal to the number of moles of the base (OH). When this occurs the equivalence point is reached and can be observed by a colour change due to the indicator. At this stage the reaction has reached its endpoint. 2/29/24, 7:25 PM An indicator is any substance in solution that changes colour when it reacts with an acid or a base. In this lab you will be using a phenolphthalein indicator which turns the clear solution to pink as the pH increases and the reaction reaches its end point. Set-up The following set-up describes the apparatus of how a titration is completed. The standard solution (of known concentration) is in a burette, which is glassware used to measure the volume of the solution. The solution you are titrating (unknown concentration) is placed in an Erlenmeyer flask which includes the indicator. In order to accurately read the volume of solution in the burette, note the volume from the bottom of the meniscus. For example, the volume of the following burette would be 18.50 mL. Procedure bottom of the meniscus 18 burette 19 standardized solution Press here for a long description. (../alt/sch3u_01.01.04a.html? ou 24327639) Erlenmeyer flask sample to be titrated (with indicator) ring stand 18.50 mL 1. Prepare a burette by rinsing it with approximately 5 mL of the NaOH solution before emptying and re-filling it with 25.0 mL of the 0.01 M NaOH solution. Use a dry clean beaker to obtain the solution from the stock bottle. https://course.ilc.tvo.org//content/enforced/24327639-SCH3U-EN-02-03-ON-(1-D-0823)/course_content/assets/locker_docs/sch3u_01.01.04.html?ou=... 2/5 2/29/24, 7:25 PM Culminating assignment: Titration lab report 2. Obtain approximately 40 mL of the HCI acid solution whose concentration is unknown in a 100 mL beaker. (Note: This does not need to be an exact measurement, as you will further measure the acid solution later.) 3. Prepare and standardize a volumetric pipette by rinsing the pipette with 1-2 mL of the acid solution before emptying and re-filling it with 10.0 mL of the acid solution. Using a volumetric pipette, transfer the 10.0 mL of the acid solution into a 125 mL Erlenmeyer flask. 4. Add three to four drops of phenolphthalein indicator. 5. Record the initial reading of the burette and dispense the NaOH solution into the flask, swirling during and after each addition. 6. As you near the endpoint of the reaction, the pink colour of the indicator will begin to last longer in solution before it is swirled away. At this stage you are only a few drops away from the endpoint. Begin adding NaOH drop by drop. Some chemists choose to use a wash bottle with distilled water to rinse the remaining solution (this will affect the volume, not the number of moles of acid or base in the flask). 7. Stop adding NaOH when a pink color is obtained that persists for at least 10 seconds. At the endpoint, one drop should change the solution from colorless to pink. Record the final reading of the burette. 8. Record the volume of NaOH by subtracting the initial reading of the burette from the final reading of the burette. 9. Repeat steps 5 to 8 for a total of three trials (you may need to refill the burette if you are running low on solution). Determine the average volume of NaOH from the three trials. Experiment and observations You are not required to perform this experiment at home therefore, you will be using the images provided for each trial to complete your results table. For each of the following trials, identify the volume of NaOH and fill in your results table with the initial burette volume from the first image and the final burette volume shown in the second image. Trial 1: Trial 2: Trial 3: https://course.ilc.tvo.org//content/enforced/24327639-SCH3U-EN-02-03-ON-(1-D-0823)/course_content/assets/locker_docs/sch3u_01.01.04.html?ou=... 3/5 2/29/24, 7:25 PM standardized solution 0.0 mL Measurement 25.0 mL 25.0 mL 2 32 25.0 mL standardized solution 0.0 mL 6 ‒‒‒‒‒‒‒‒ 12 standardized solution 0.0 mL 2.3 mL Culminating assignment: Titration lab report Volume of HCl (mL) Initial burette volume of NaOH (mL) 6.8 mL 11.1 mL | ********* Trial 1 After the titration is complete standardized solution 0.0 mL 25.0 mL Trial 2 After the titration is complete standardized solution 0.0 mL 25.0 mL 6 25.0 mL 12 After the titration is complete standardized solution 0.0 mL 15 16 6.8 mL ||||||||| Results and calculations When you are collecting your data, make sure you accurately fill in the following table. Use the appropriate significant digits. 11.1 mL Trial 3 15.5 mL https://course.ilc.tvo.org//content/enforced/24327639-SCH3U-EN-02-03-ON-(1-D-0823)/course_content/assets/locker_docs/sch3u_01.01.04.html?ou=... 4/5 2/29/24, 7:25 PM Measurement Final burette volume of NaOH (mL) Volume of NaOH (mL) Average volume of NaOH (mL) Culminating assignment: Titration lab report Trial 1 Trial 2 Trial 3 Discussion and analysis Complete the following discussion questions as a part of your lab report. 1. Write the balanced equation for the reaction involved in this experiment (include state symbols). (1 mark) 2. Determine the average volume of NaOH used. (1 mark) 3. Calculate the moles of NaOH used. Show your work. (2 marks) 4. Calculate the moles of HCl used. Show your work. (2 marks) 5. Calculate the unknown concentration of the acid HCl. Show your full solution using the GRASS method. (3 marks) 6. While performing a titration, many chemists use a wash bottle and distilled water to wash down any solution that may have splashed higher up. This would increase the volume of the acid in the flask. Will it have an effect on the results, why or why not? (2 marks) https://course.ilc.tvo.org//content/enforced/24327639-SCH3U-EN-02-03-ON-(1-D-0823)/course_content/assets/locker_docs/sch3u_01.01.04.html?ou=... 5/5