Need help! Pas Name Section Experiment 22 Data and Observations: Properties of A

Question

Need help!

Pas Name Section Experiment 22 Data and Observations: Properties of A. Acid-Base Indicators Color of methyl violet in water dh anle 2. Reagent causing color change 3. Reagent causing shift back Explain, by considering how changes in H' will cause Reaction 4 to shift to right and left, why the reagents in Steps 2 and 3 caused the solution to change color. Note that Reactions 3 and 4 must both go to equilibrium after a reagent is added. B. Solubility Equilibrium; Finding a Value for Kup 2. Vol 0.30 M Pb(NO): = 5.0 mL moles Phe-Isrx vrstock)I-1.5 x 10-i moles Observations: No reactiC ml: moles Cir added Li tions in bot water dssalasd in cold water rbtne d moles 3. Vol. 0.30 M HCI used cold water tr 5. Volume of H,O added to dissolve PbCl mL Total volume of solution mL a. Explain why PbCl, did not precipitate immediately on addition of HCI. (What condition must be met reper + by IPb] and (Cl] if PbCl, is to form?) (continued on following page

Explanation / Answer

A) Acid -base indicators:

Discussion:

Methyl violet shows green color in the pH range 0-1.6 (acidic medium) and its color is blue-violet in basic medium ,pH>1.6,In neutral medium like water with pH ,its color is violet.

If In indicates the indicator methyl violet then in acidic medium its form is HIn and in basic medium its form is In-

HIn (green) <--->H+ +In-(violet) [acid -base equilibrium]

On adding acid, 6M HCl, more H+ is added to the system.As more product component gets added ,so the equilibrium shifts to the left (reverse direction) producing more HIn (green).[Le Chatlier's principle]

On adding base , 6M NaOH, H+ is consumed by OH-,so H+ concentration decreases.

H+ (aq)+OH- (aq)-->H2O(l)

As product component decreases ,so the equilibrium shifts to the right (forward direction) producing more In- (violet).[Le Chatlier's principle]

Answers:

1) violet

2)6M HCl (color changes to green)

3) 6M HCl

explained above

Related Questions

Navigate

• Browse (All)
• Browse N
• Subjects

---

---

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