Question

Part IV. 1. Zn(OH)2 (s) ⇌ Zn (aq) + 2 OH (aq) (This is the lab procedure)

2+ 2-
2. Zn (aq) + 4 OH (aq) ⇌ Zn(OH)4 (aq)

2+
3. Zn (aq) + 4 NH3 (aq) ⇌ Zn(NH3)4 (aq)

1. In a test tube add 2 mL 0.1M Zn(NO3)2. Add one drop of 6M NaOH and stir. Record your observations.

r. What is happening as NaOH is added?

2. Add more 6M NaOH dropwise until a change is observed. Record your observations.

s. What happened to the solid? What is now in the solution? Explain how the equilibrium of the complex ion reaction affected the equilibrium of the solid Zn(OH)2.
3. In a new test tube add 2 mL 0.1M Zn(NO3)2. Add one drop of 6M NH3 and stir. Record your observations. Add 2mL more 6M NH3 until a change is observed. Record your observations.

t. What happened to the solid? What is now in the solution? Explain how the equilibrium of the complex ion reaction affected the equilibrium of the solid Zn(OH)2. 4. In another new test tube add 2 mL 0.1M Zn(NO3)2. Add one drop of 6M NaOH and stir. Record your observations. Add 6M HCl dropwise until a change is observed. Record your observations.
.

5. In a test tube add 2 mL 0.1M Mg(NO3)2. Add one drop of 6M NaOH and stir. Record your observations.

u. What is happening as HCl is added? How is HCl affecting the equilibrium of Zn(OH)2?

2+ – Mg(OH)2 (s) ⇌ Mg (aq) + 2 OH (aq)

v. What is happening as NaOH is added?

6. Add 6M NaOH dropwise for 10 drops. Did a change happen? Record your observations.

w. What happened to the solid? Did magnesium (II) ion form a complex ion like Zn? How do you know? What is your evidence?

7. . In a new test tube add 2 mL 0.1M Mg(NO3)2. Add one drop of 6M NH3 and stir. Record your observations. Add 2 mL more 6M NH3. Record your observations.
x. What happened to the solid? Did magnesium (II) ion form a complex ion like Zn? How do you know? What is your evidence?

8. In another new test tube add 2 mL 0.1M Mg(NO3)2. Add one drop of 6M NaOH and stir. Record your observations. Add 6M HCl dropwise until a change is observed. Record your observations..

y. What is happening as HCl is added? How is HCl affecting the equilibrium of Mg(OH)2?

Part IV. - I need help having these questions answered.

Write the relevant (3) Zn equilibrium reaction(s) here: (0.75)

15.What happened as NaOH was added in a single drop to a Zn+2 solution? (0.25)

16. What happened to the Zn(OH)2 as excess NaOH was added? What is now in the solution? Using your observations as evidence and your understanding of LCP, explain how the equilibrium of the complex ion reaction affected the earlier equilibrium of the solid Zn(OH)2. Explain BOTH reactions equilibrium shifts. (0.75)

17. What happened as NH3 was added drop by drop to the Zn+2 solution? What happened when excess NH3 was added? What is now in the solution? Using your observations as evidence and your understanding of LCP, explain how the equilibrium of the complex ion reaction affected the earlier equilibrium of the solid Zn(OH)2. Explain BOTH reactions equilibrium shifts. (0.75)

18. What happened as HCl was added to the Zn(OH)2 equilibrium? What did the HCl react with? How did this reaction change the equilibrium position of reaction 1? (0.5)

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Write the relevant Mg equilibrium reaction here: (0.25)
19. What happened as NaOH was added in a single drop to a Mg+2 solution? (0.25)

20. What happened to the Mg(OH)2 as more NaOH was added? Did Mg2+ form complex ion with OH-? Which way did equilibrium shift? (0.75)

21. What happened as NH3 was added by drop to the Mg+2 solution? What happened when excess NH3 was added? Did Mg2+ form complex ion with OH-? Which way did equilibrium shift? (0.75)

22. What happened as HCl was added to the Mg(OH)2 equilibrium? How did HCl affect the equilibrium of Mg(OH)2? Which way did equilibrium shift? (0.25)