Question

Name: CHE 121 Lab: Titration Purpose: To determine the M of an unknown NaOH solution and then to determine the M of vinegar, Reaction 1: HCI + NaOH NaCl + H2O Procedures 1 Rinse all burets and flasks with tiled water. Discard washin sink 2 Rinse buret with 5 ml of Base Discard in waste container 3. Fill buret with Base. Record starting volume 4 Add 10 ml of distilled water to deared flask 5. Pipet eactly 10.0 ml of acid to flask with water 6. Add 2 drops of Indicator 7. Add NaOH base slowly. Swirl. Add base until 1 drop turns the solution very faint pink. 8. Record the volume of the base. 9. Do another trial. Use the ending value of the base as the new trials starting value 10 Add water, acid and indicator to flask as before. 11 Titrate to a faint pink. Record volumes. 12 Do a third trial 1.20 M HCI This is sample data from a previous lab Data Table: Trial 1 Trial 2 HCI ml 10.00 ml 10.00ml Start NaOH ml 10.00 ml 8.31 ml End NaOH ml 8.31 ml 15.95 ml used NaOH ml 8.31 ml 7.64 ml Calculations: 1. Calculate the average ml NaOH used in the 3 trials Trial 3 10.00ml 15.95 ml 23.78 7.83 ml 2. Using stoichiometry for neutralization, calculate the Molarity of your NaOH solution. Nacl + H20 (start with HCI) HCl + 10.00 ml 1.20M NaOH ave ml from #1 ?M 3. Using the M of NaOH from #2 as (OH-], what is the [H3O+] (use kw-[H3O+][OH-], solve for [H3O+]) 4. What is the pH using the [H3O+] in #3 (use pH--log [H3O+]