Acid & Base Review

A) B)C) D)

1. Which compound is an electrolyte?

A) pH of KCl(aq)B) pH of KCl(s)C) electrical conductivity of KCl(aq)D) electrical conductivity of KCl(s)

2. Which laboratory test result can be used to determine if KCl(s) isan electrolyte?

A) NH3(g) B) H2O( )C) NH4+(aq) D) OH–(aq)

3. Given the equation representing a reversible reaction:

NH3(g) + H2O( ) NH4+(aq) + OH–(aq)According to one acid-base theory, the reactant that donates an H+ ion in the forward reaction is

A) hydrogen ions B) hydronium ionsC) hydroxide ions D) oxide ions

4. When dissolved in water, an Arrhenius base yields

A) ammonia and methane B) ammonia and a saltC) water and methane D) water and a salt

5. According to the Arrhenius theory, a base reacts with an acid toproduce

A) CaO B) HCI C) K2O D) NH3

6. Which compound is an Arrhenius acid?

A) a salt B) a hydrocarbonC) an Arrhenius acid D) an Arrhenius base

7. When one compound dissolves in water, the only positive ionproduced in the solution isH3O+ (aq). This compound is classified as

A) hydroxide B) hydroniumC) hypochlorite D) perchlorate

8. Given the equation:

HCl(g) + H2O( ) X(aq) + Cl–(aq)Which ion is represented by X?

A) CH3OH B) CH3Cl C) LiOH D) LiCl

9. Which substance is an Arrhenius base?

A) changes litmus from red to blueB) changes phenolphthalein from colorless to pinkC) produces hydronium ions as the only positive ions in an

aqueous solution

D) produces hydroxide ions as the only negative ions in anaqueous solution

10. According to the Arrhenius theory, an acid is a substance that

A) decreases 1 pH unit B) decreases 10 pH unitsC) increases 1 pH unit D) increases 10 pH units

11. When the hydronium ion concentration of a solution is increasedby a factor of 10, the pH value of the solution

A) 1.0 B) 0.20 C) 3.0 D) 20

12. A solution with a pH of 2.0 has a hydronium ion concentrationten times greater than a solution with a pH of

A) 1 B) 2 C) 3 D) 11

13. What is the pH of a 0.001 M HNO3 solution?

A) 6, which is acidic B) 8, which is basicC) 6, which is basic D) 8, which is acidic

14. The [H3O+] of a solution is 1 × 10–8. This solution has a pH of

A) acidic and has a pH of 4B) acidic and has a pH of 10C) basic and has a pH of 4D) basic and has a pH of 10

15. The H3O+ ion concentration of a solution is 1 × 10–4 mole perliter. This solution is

A) a solution in which bromthymol blue is blueB) a solution in which bromcresol green is blueC) a solution in which phenolphthalein is pinkD) a solution in which methyl orange is red

16. Based on the results of testing colorless solutions withindicators, which solution is most acidic?

A) bromthymol blue B) bromcresol greenC) litmus D) thymol blue

17. Which indicator would best distinguish between a solution witha pH of 3.5 and a solution with a pH of 5.5

A) B)C) D)

18. According to one acid-base theory, a base is an

A) H2O( ) B) NH3(g)C) NH4+(aq) D) OH–(aq)

19. Given the equation representing a reaction at equilibrium:

NH3(g)+ H2O( ) NH4+ (aq) + OH–(aq)

The H+ acceptor for the forward reaction is

A) HSO4– and SO42– B) HSO4– and HPO42–

C) SO42– and H2PO4– D) SO42– and HPO42–

20. Given the reaction:

HSO4– + HPO4 2– « SO42– + H2PO4

Which pair represents an acid and its conjugate base?

Acid & Base Review

Base your answers to questions 21 and 22 on the information below and on your knowledge of chemistry.

The pH of various aqueous solutions are shown in the table below.

21. State how many times greater the hydronium ion concentration in the HCl(aq) is than the hydronium ion concentration inthe HC2H3O2(aq).

22. Complete the table by writing the color of thymol blue in the NaCl(aq) and in the NaOH(aq) solutions.

A) H2O B) HCl C) H3O+ D) Cl–

23. Given the reaction:

H2O + HCl « H3O+ + Cl–

The Brönsted-Lowry base for the forward reaction is

A) H2SO4 B) H3O+ C) HSO3– D) SO42–

24. Which is the conjugate acid of HSO4–?

A) CaCl2 B) CaH2 C) HClO D) HClO2

25. Which compound is produced when HCl(aq) is neutralized byCa(OH)2(aq)?

A) KCl(aq) B) CaO(aq)C) NaOH(aq) D) H2SO4(aq)

26. Which solution reacts with LiOH(aq) to produce a salt andwater?

A) base + acid ® salt + waterB) base + salt ® water + acidC) salt + acid ® base + waterD) salt + water ® acid + base

27. Which word equation represents a neutralization reaction?

A) 4Fe(s) + 3O2(g) ® Fe2O3(s)B) 2H2(g) + O2(g) ® 2H2O( )C) HNO3(aq) + KOH(aq) ® KNO3(aq) + H2O( )D) AgNO3(aq) + KCl(aq) ® KNO3(aq) + AgCl(s)

28. Which equation represents a neutralization reaction?

Acid & Base Review

Base your answers to questions 29 and 30 on the information below and on your knowledge of chemistry.

During a laboratory activity, a student places 25.0 mL of HCl(aq) of unknown concentration into a flask. Thestudent adds four drops of phenolphthalein to the solution in the flask. The solution is titrated with 0.150 M KOH(aq)until the solution appears faint pink. The volume of KOH(aq) added is 18.5 mL.

29. Complete the equationfor the neutralization reaction that occurs during the titration.

30. Determine the concentration of the HCl(aq) solution, using the titration data.

31. Base your answer to the following question on the information below.

In a titration, 20.0 milliliters of 0.15 M HCl(aq) is exactly neutralized by 18.0 milliliters of KOH(aq).Compare the number of moles of H+(aq) ions to the number of moles of OH–(aq) ions in the titration mixture when theHCl(aq) is exactly neutralized by the KOH(aq).

Base your answers to questions 32 through 34 on theinformation below.

Some carbonated beverages are made by forcing carbon dioxidegas into a beverage solution. When a bottle of one kind ofcarbonated beverage is first opened, the beverage has a pHvalue of 3.

32. After the beverage bottle is left open for several hours, thehydronium ion concentration in the beverage solution decreasesto of the original concentration. Determine the new pH ofthe beverage solution.

33. Using Table M, identify one indicator that is yellow in a solutionthat has the same pH value as this beverage.

34. State, in terms of the pH scale, why this beverage is classified asacidic.

Acid & Base Review

Base your answers to questions 35 through 37 on the information below.

In liquid water, an equilibrium exists between H2O( ) molecules, H+(aq) ions, and OH-(aq) ions. A personexperiencing acid indigestion after drinking tomato juice can ingest milk of magnesia to reduce the acidity of thestomach contents. Tomato juice has a pH value of 4. Milk of magnesia, a mixture of magnesium hydroxide and water,has a pH value of 10.

35. What is the color of thymol blue indicator when placed in a sample of milk of magnesia?

36. Identify the negative ion found in milk of magnesia.

37. Compare the hydrogen ion concentration in tomato juice to the hydrogen ion concentration in milk of magnesia.

Base your answers to questions 38 through 40 on the information below.

Soil pH can affect the development of plants. For example, a hydrangea plant produces blue flowers when grown inacidic soil but pink flowers when grown in basic soil. Evergreen plants can show a yellowing of foliage, called chlorosis,when grown in soil that is too basic. Acidic soil can be neutralized by treating it with calcium hydroxide, Ca(OH)2, commonly called slaked lime. Slakedlime is slightly soluble in water.

38. Write an equation, using symbols or words, for the neutralization of the ions in acidic soil by the ions released by slakedlime in water.

39. An evergreen plant has yellowing foliage. The soil surrounding the plant is tested with methyl orange and bromthymolblue. Both indicators turn yellow in the soil tests. State, in terms of pH value, why the yellowing of the plant is not due tochlorosis.

40. Compare the hydrogen ion concentration to the hydroxide ion concentration in soil when a hydrangea plant produces pinkflowers.

Answer KeyAcid and base review

1. D

2. C

3. B

4. C

5. D

6. B

7. C

8. B

9. C

10. C

11. A

12. C

13. C

14. B

15. A

16. D

17. B

18. A

19. B

20. A

21. 1022.

23. A

24. A

25. A

26. D

27. A

28. C

29. – – –

30. –0.111 M –0.11 M–0.1 M

31. —The numberof moles of H+(aq)ions equals thenumber of moles ofOH–(aq) ions. —The numberof hydrogen ions isthe same as thenumber of hydroxideions.

32. – 633. – bromthymol blue –

bromcresol green –thymol blue

34. – The beverage isacidic because its pHvalue is below 7. – ApH of 3 is in the acidrange on the pHscale.

35. blue36. OH–(aq) or OH–

or hydroxide ion37. –The H+ ion

concentration intomato juice is 106

times greater. –Thehydrogen ionconcentration intomato juice isgreater than that inmilk of magnesia.–Milk of magnesiahas a lowerconcentration of H3O+ ions.

38. Examples: H3O+(aq)+ OH-(aq) ® 2H2O() ; H+ + OH- ® HOHhydrogen ions +hydroxide ions ® water; hydroxideions + hydroniumions ® water

39. Examples: – The pHis between 4.4 and6.0, which indicatesan acidic soil. – ThepH of the soilsurrounding the plantis below 6.0. – Forchlorosis, the soil pHmust be above 7.

40. Examples: – Thehydroxide ionconcentration isgreater than thehydrogen ionconcentration. – TheH3O+ concentrationis less than the OH-

concentration. [OH-]> [H3O+]