CHEMISTRY 12 – APPLICATIONS OF ACIDS AND BASES Review KEY

F1) Demonstrate an ability to design and analyse a titration experiment

1. Calculate the pH resulting from mixing 35.0 mL of 0.200 M HCl with 75.0 mL of 0.150 M NaOH. (3 marks)

2. What mass of Ca(OH)2(s) must be added to 750 mL of 0.250 M HCl to

create a solution with a pH = 3.150? (3 marks)

3. Write the net ionic reaction that occurs when NaOH is titrated with HNO3.

4.

5. What does the term end point mean?

6. What is a standardized solution?

7. When titrating HCl with NH3, what indicator should be used and why?

8. In the reaction:

H2SO4 + 2NaOH → Na2SO4 + 2H2O

an equivalence point occurs when 22.74 mL of 0.1893 M NaOH is added

to a 25.00 mL portion of H2SO4.

a. What is the [H2SO4]?

b. What indicator would you choose for the reaction and why?

9. A 25.00 mL of an H3PO4 is titrated using 0.1472 M NaOH. The results

obtained are:

Trial 1 Trial 2 Trial 3

Final Volume 37.89 46.82 39.50

Initial Volume 1.25 10.58 3.24

Calculate the [acid].

10. What is the approximate pH value at the equivalence point for the

following titrations. Draw the titration curves you would see.

A. HCN and KOH

B. HClO4 and LiOH

C. NH3 and HCl

11. Explain why the pH for the titration of CH3COOH and NaOH will not be at

pH 7 at the equivalence point

F2) Describe an indicator as an equilibrium system

12. What is the transition point of an indicator?

13. Consider the following equilibrium for an indicator that changes at a pH of

6-8:

HInd + H2O <—> Ind- + H3O+

yellow blue

a. What colour will be in an acid? Why?

b. What colour will it be in a base? Why?

F3) Perform and interpret calculations involving the pH and Ka for an indicator

14. What is the Ka for the indicator phenolpthalein?

15. Which of the following is/are true at the transition point of an indicator?

A. Ka = [HInd]

B. [HInd] = [Ind-]

C. pH = [HInd]

D. Ka = [H3O+]

E. Ka = Kb

F. pH = pKa

F4) Describe the hydrolysis of ions in salt solutions

16. What hydrolysis reaction will occur when the salt NH4Cl is dissolved in water?

F5) Analyse the extent of hydrolysis in salt solutions and predict whether a salt

solution would be acidic, basic, or neutral (compare Ka and Kb values, if

necessary)

17. Consider the salt NaH2PO4.

a. Write the dissociation reaction

b. Write the hydrolysis reaction

c. Determine if the salt forms an acidic, basic, or neutral solution.

F6) Describe buffers as equilibrium systems

18.

19. Explain the answer to the above question

F7) Describe the preparation of buffer systems

20. Describe how you would make a buffer.

F8) Predict what will happen when oxides dissolve in rain water

21.

22. Which of the following combinations will form a buffer solution.

A. HI and NaI

B. HF and KF

C. NH4Cl and NH3

D. HCN and NaCl

E. KHCO3 and H2CO3

23. What is the approximate pH of normal rainwater? Why?

24. List 2 gases responsible for acid rain and their sources.