Add 50.00 mL of the base to the burette. Record the initial burette reading.

  

Add 50.00 mL of the base to the burette. Record the initial burette reading. Step 2: Conducting Your Experiment Select and hold the burette containing the base, and move it over the top of the flask containing the unknown acid. A measurement box will appear. Begin by adding the base to the unknown acid at 5.00 mL increments (watch the pH readings in the panel at the left). Record each increment of base added to the unknown acid, along with the corresponding pH. As you approach the colour change, reduce the amount of base to 1.00 mL increments, then 0.50 mL increments. Note: you can use even smaller increments to get more precise results. Once you have identified the endpoint, repeat the procedure but go past the endpoint. Continue adding base at your selected increment until the pH is approximately 11. Step 3: Graphing and Analyzing Your Results Use your data to calculate the concentration (i.e. molar concentration) of the unknown acid. Graph your titration curve. Place the volume of base on the x-axis and the pH of the unknown acid solution on the y-axis. Find the equivalence point on your graph, and use the volume at this point to calculate the concentration of the unknown acid. When the colour of the solution changes to pink, you have passed the endpoint. However, this gives you a good idea where the endpoint is: it is the volume just before the solution changes colour. In your discussion, comment on the two ways of calculating the acid concentration. Also include a description of how the number of moles of base affected the pH of the unknown solution. STEP 4: COMMUNICATING YOUR RESULTS Once you have completed your test(s), communicate your results in a lab report. Your lab report should include the following sections: purpose/objective, materials, procedure, observations, results, discussion, and conclusion. Note: there is no testable question/hypothesis for this experiment. In its place, simply report the purpose or objective of the experiment. Assessment Details Your submission should include the following: Your report Your titration curve The equivalence point for your titration