Acids     Quiz #7         pH Relationships, Amphiprotic Calculations

1.         In water, the hydrogen phosphate ion, HPO42-, will act as

A.        An acid because Ka < Kb

B.        An acid because Ka > Kb

C.        A base because Ka < Kb

D.        A base because Ka > Kb

2.         A student records the pH of 1.0 M solution of two acids

 Acid pH X 4.0 Y 2.0

Which of the following statements can be concluded from the above data?

A.        Acid X is stronger than acid Y

B.        Acid X and acid Y are both weak

C.        Acid X is diprotic while acid Y is monoprotic

D.        Acid X is 100 times more concentrated than acid Y

3.         When added to water, the hydrogen carbonate ion, HCO3-, produces a solution,

which is

A.        basic because Kb is greater than Ka

B.        basic because Ka is greater than Kb

C.        acidic because Ka is greater than Kb

D.        acidic because Kb is greater than Ka

4.         The concentration, Ka and pH values of four acids are given in the following table

 ACID Concentration Ka pH HA 3.0 M 2.0 x 10-5 2.1 HB 0.7 M 4.0 x 10-5 2.3 HC 4.0 M 1.0 x 10-5 2.2 HD 1.5 M 1.3 x 10-5 2.4

Based on this data, the strongest acid is

A.        HA

B.        HB

C.        HC

D.        HD

5.         Which of the following 0.10 M solutions is the most acidic?

A.        AlCl3

B.        FeCl3

C.        CrCl3

D.        NH4Cl

6.         Which of the following acid-base indicators has a transition point between pH 7

and pH 9?

A.        Ethyl red, Ka = 8 x 10-2

B.        Congo red, Ka = 9.0 x 10-3

C.        Cresol red, Ka = 1.0 x 10-8

D.        Alizarin blue, Ka = 7.0 x 10-11

7.         Which of the following would be a typical pH of lemon juice?

A.        1.0

B.        3.0

C.        6.8

D.        7.2

8.         What is the [KOH] in a KOH solution that has a pH = 13.00?

A.        0.10 M

B.        0.56 M

C.        1.0 M

D.        1.0  x  10-13 M

9.         What is the [H3O+] in 0.70 M HCN ?

A.        0.70 M

B.        1.9  x  10-5 M

C.        1.0  x  10-7 M

D.        3.4  x  10-10 M

10.       The S2- ion is a base with an equilibrium constant of 0.77, what is the Ka value

for HS-?

A.        1.3  x  10-14

B.        9.1  x  10-8

C.        1.1  x  10-7

D.        7.7  x  1013

11.       Which of the following is true as a result of the predominant hydrolysis of

NaHCO3?

Solution                       Reason

A.        basic                            Ka  >  Kb

B.        basic                            Ka  <  Kb

C.        acidic                          Ka  >  Kb

D.        acidic                          Ka  <  Kb

12.       Consider the ionization of water:   H2O  +  H2O       H3O+   +   OH-

What happens to the pH when 0.1 M NaOH is added to water?

A.        pH increases since [H3O+] increases.

B.        pH increases since [H3O+] decreases.

C.        pH decreases since [H3O+] increases.

D.        pH decreases since [H3O+] decreases.

13.       Which of the following amphiprotic ions will act predominantly as a base in

solution?

A.        HSO3-

B.        HSO4-

C.        H2PO4-

D.        HPO42-

14.       Which of the following statements is true for a alkaline solution at 25 0C ?

A.        pH  <  7.0

B.        pOH  >  7.0

C.        [H3O+]  >  [OH-]

D.        [H3O+]  <  [OH-]

15.       What is the [OH-] in 0.025 M HCl ?

A.        2.5  x  10-16 M

B.        4.0  x  10-13 M

C.        2.5  x  10-2 M

D.        2.5  x  10-12 M

16.       Which of the following statements is true for an acidic solution at 25 0C ?

A.        pH  >  7.0

B.        pOH  <  7.0

C.        [H3O+]  <  [OH-]

D.        [H3O+]  >  [OH-]

17.       What is the [H+] in 0.025 M NaOH?

A.        2.5  x  10-16 M

B.        4.0  x  10-13 M

C.        2.5  x  10-2 M

D.        2.5  x  10-12 M

18.       What [H3O+] results when 25 mL of  1.0 M HCl is mixed with 10 mL of

2.0 M KOH ?

A.        0.70 M

B.        0.00 M

C.        0.10 M

D.        0.14 M

19.       What is the pH of 0.70 M HCN ?

A.        0.70 M

B.        1.9  x  10-5 M

C.        5.32

D.        4.73

20.       Consider the following indicator equilibrium:

HInd +  H2O     H3O+   +      Ind-

yellow                                       blue

What is the result of adding FeCl3 to this indicator?

Equilibrium Shift         Colour

A.        left                               blue

B.        left                              yellow

C.        right                             blue

D.        right                             yellow

21.       An indicator changes colour when 1.0 M HCl is added.  If the indicator has a

Ka =  1.0  x  10-10, determine the indicator and the pH at its transition point.

Indicator                      pH

A.        phenolphthalein           4.0

B.        phenolphthalein           10.0

C.        thymolphthalein           4.0

D.        thymolphthalein         10.0

22.       What is the Kb value for HC6H5O72- ?

A.        1.0  x  10-14

B.        5.9  x  10-10

C.        2.4  x  10-8

D.        4.1  x  107

23.       What is produced when MgO is added to water?

A.        the metal Mg

B.        the acid HMgO

C.        the base Mg(OH)2

D.        the amphiprotic species HMgO2

24.       Which of the following is a major source of NO2(g), which contributes to

the problem of acid rain?

A.        a smelter

B.        an air conditioner

C.        a nuclear power plant

D.        the automobile engine

25.       The indicator bromothymol blue can be described by the following equilibrium

equation:

HInd +  H2O     H3O+   +      Ind-

yellow                                      blue

A base is added to the above indicator. After equilibrium has been re-established,

how do the H3O+ and the colour of the solution compare with the original

equilibrium?

H3O+                Colour of Solution

A.        decreases       turns blue

B.        decreases        turns yellow

C.        increases         turns blue

D.        increases         turns yellow

26.       The indicator bromothymol blue can be described by the following equilibrium

equation:

HInd +  H2O     H3O+   +      Ind-

yellow                                      blue

An acid is added to the above indicator. After equilibrium has been re-established,

how do the H3O+ and the colour of the solution compare with the original

equilibrium?

H3O+                Colour of Solution

A.        decreases        turns blue

B.        decreases        turns yellow

C.        increases         turns blue

D.        increases        turns yellow

27.       What is the Ka value for the indicator neutral red?

A.        1  x  10-14

B.        4  x  10-8

C.        7.4

D.        14.0

28.       What is a common source of SO2(g) ?

A.        automobiles

B.        a car battery

D.        oxidation of iron

29.       What is the [H3O+] in 0.70 M HCN ?

A.        0.70 M

B.        1.9  x  10-5 M

C.        1.0  x  10-6 M

D.        2.4  x  10-10 M

30.       What is the value of pKw for water at 25 0C ?

A.        1.0  x  10-14

B.        10  x  10-7

C.        7.00

D.        14.00