1g Ca(OH)2 in 125mL flask fill half with distilled water 1g Ca(OH)2 in 125nL fla

Question

1g Ca(OH)2 in 125mL flask fill half with distilled water 1g Ca(OH)2 in 125nL flask fill half full with .010 M CaCl2 Pre-lab Assignment (25 pts) - must be turned in at the start of lab In this lab, you will be using bromothymol blue as a pH indicator. Look up the behavior and p bromothymol blue from the previous lab on indicators. 1. a. What color change is expected in this lab when OH is titrated with HCI? Be clear about the expected starting and ending colors of the solution in the Erlenmeyer flask b. What is the pH at the equivalence point for the titration? pH at the end point? Explain. c. Based on its pK, explain why bromothymol blue is a good choice for this experiment. In parts of this lab you must remove and filter a saturated Ca(OH)2 solution from the flask. Explain why it is essential that the filtrate be as clear as possible before titrating with the HCI solution 2. 3. In Part D, the saturated solution consists of both Ca(OH)2 and CaCl. Qualitatively, how is the molar solubility of Ca(OH)2 affected by the presence of CaCl2 in the solution?

Explanation / Answer

1 a) pKa of bromothymol blue is 7.1 with pH range of 6.0-7.6. As HCl is added to the Ca(OH)2 solution containing the bromothymol indicator the starting color is blue which changes to green at the equivalence point and finally to yellow at the end point.

b) Since this titration of strong acid vs strong base, result is a neutralization recation forming salt and water. Therfore the pH at equivalence point will be 7. At the end point pH will be less than 7.

c) Since the pH at equivalence point is 7, the indicator with pka close to this is bromothymol blue with a value of 7.1

2) A clear filterate is essential to properly observe the color change .

Related Questions

Navigate

• Browse (All)
• Browse 1
• Subjects

---

---

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