Tear this page out of your laboratory manual and submit it to your TA with your

Question

Tear this page out of your laboratory manual and submit it to your TA with your answers. B. Post-Lab Assessment Questions: Why is it important for all of your glassware to be clean and dry before performing a titration? Why are air bubbles in the burette tip a possible source of error in a titration experiment? How do you remove air bubbles from the burette tip? Dr. Sweeney is research chemistry who recently discovered an old bottle labeled perchloric acid (HClO_4) in the back of his research laboratory. After verifying that the contents of the bottle were indeed HClO_4 Dr. Sweeney was interested in determining the concentration of HClO_4 in the bottle. To determine the concentration of HClO_4 Dr. Sweeney performed a titration using 20 mL of HClO_4 and phenolphthalein. Dr Sweeney determined that it took 24 mL of 0.040 M NaOH to reach the endpoint of the titration. a) What did Dr. Sweeney observe to indicate the endpoint in his titration? b) Write the chemical equation th

Explanation / Answer

Q1.

we must have a clean glassware in order to prevent "contamination" and "pollution" of other materials. Specially if they are reactive. If they are not, we will have inaccurate reading of volume and mass which will later interfere with our calculations.

They must be dry to avoid humidity, since water favours lots of reactions such as oxidation, hydration, etc...

Q2.

The bubbles account for volume, which is actually air and not the titrant ( liquid inside the burette), therefore, we will account for a higher mass(volume) than it actually is

We can remove bubbles via:

- Tapping until air bubbles go to the top

- allowing some volume to go out, so the bubbles oof air go out as well

Please consider posting multiple questions and subquestions in different set of Q&A. According to Chegg's guidelines, we are not allowed to answer to multiple questions in a single set of Q&A

Related Questions

Navigate

• Browse (All)
• Browse T
• Subjects

---

---

Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.