Ch. 16 Acid Base Homework

 20 points

Check out pages 483-491 for additional help on how to do these problems

 

Determining the pH of a STRONG ACID solution based on its [ ]:

                1.  Remember that STRONG ACIDS completely dissociate in water. 

2.  Therefore, the [strong acid] = [H3O+]

3.  Remember that pH = -log[H3O+]

 

For Questions 1-5: 

a.  Name each of these STRONG ACIDS

b.  Determine the pH of the following concentrations of STRONG ACIDS

1.  [HCl] =  0.01 M          b.  2

2.  [HBr] =  0.05 M          b.  1.3

3.  [HI] = 1.00 M              b.  0

4.  [HNO3] = 12.0 M        b.  – 1.08

5.  [H2SO4] = 6.00 M        b.  – 0.77

 

For Questions 6-10, determine the [of a STRONG ACID] based on its pH:

6.  pH = 1.00        = 0.1M

7.  pH = 4.00        =1x 10-4 M

8.  pH = -0.34       = 2.19 M

9.  pH = -1.00       = 10 M

10.  pH = 13.0      =  1 x 10-13

 

Determining the pH of  WATER (example:  testing your swimming pool):

                1.  Remember that H2O(l)  + H2O (l)  <-> H3O+ (aq)  +  OH- (aq).

                2.  Remember that kw  must always equal 1.00 x 10-14. And that H2O(l) is not part of the kw.

                3.  So, kw = 1.00 x 10-14. = [H3O+] [OH-].

                4.  Remember Le Chatelier’s principle which says if you increase  [H3O+], then you will have

to decrease [OH-] in order to keep the kw at 1.00 x 10-14.  And vice versa.

5.  Remember that pH of a solution is equal to –log [H3O+]

 

 For Questions #11-17

a.  Find the pH of these solutions given the [H3O+] and say if the solution is acidic or basic.

b.  Find the [OH-] in each of these solutions

c.  Find the pOH in each of these solutions.

11. [H3O+]:  1.00 x 10-5                 a.  5                   b.  1x 10-9                           c.   9

12. [H3O+]:  1.00 x 10-3                a.   3                   b.  1x 10-11                         c.  11

13. [H3O+]:  1.00 x 10-10              a.  10                  b.  1x 10-4                           c.  4                     * what do you get

14. [H3O+]:  1.00 x 10-13              a.  13                  b.  1x10-1                             c.  1                         when you add pH

15. [H3O+]:  2.67 x 10-1                a.   0.57              b.  3.75x 10-14                  c.  13.4                     and pOH?

16. [H3O+]:  5.89 x 10-7                a.   6.23              b.  1.70x 10-8                   c.   7.77

17. [H3O+]:  3.89 x 10-12              a.   11.4              b.  2.57x 10-3                   c.   2.59

 

For Questions #18-24:

a.  find the [H3O+] based on the following pH’s

b.  find the [OH-] in each of these solutions.

c.  Find the pOH in each of these solutions.

18.  pH =  1.00            a.  1x 10-1  M                       b.  1x 10-13  M                           c. 13                 

19.  pH =  3.00            a.  1x 10-3     M                    b.  1x 10-11 M                 c.  11

20.  pH =  4.00            a.  1x 10-4         M                b.  1x 10-10 M                 c. 10

21.  pH =  5.87            a.  1.35x 10-6M                  b. 7.41x 10-9 M               c.  8.13

22.  pH =  3.91            a.  1.23x 10-4M                   b. 8.13x 10-11 M            c. 10.1

23.  pH =  28.0            a.  1.00x 10-28M                 b.  1x 1014 M                 c.  -14

24.  pH =  19.0            a.  1.00x 10-19M                b.   1x 105 M                   c.  -5

Finding the pH of some WEAK ACIDS (Please look at the ka’s listed for weak acids next to each problem.)

                1.  Remember Ka = [products]/[reactants] and only include (aq) and (g) in the Ka.

                2.  H2O is ALWAYS a LIQUID

                3.  [B-] = the concentration of the conjugate base – example:  Conjugate base of HF is F-

                4.  Unless otherwise specified (and it won’t be), you can assume that [H3O+] = [B-]

                5.  Remember that pH = -log [H3O+]

 

For questions #25-30: 

a.  Write the Ka expression and set it equal to the numerical value you find below

b.  Solve for [H3O+]

c.  Solve for pH

 

25.  Assume you have 0.01 M of HF                   (Ka = 6.6 x 10-4)                 b.  2.56x 10-3 M             c.  2.59

26.  Assume you have 0.23 M of HCOOH          (Ka = 1.8 x 10-4)                 b.  6.43x 10-3 M             c.  2.19

27.  Assume you have 4.00 M of CH3COOH      (Ka = 1.8 x 10-5)                 b.  8.49x 10-3 M             c.  2.07

28.  Assume you have 8.50 M of H2CO3                  (Ka = 4.4 x 10-7)                            b.  1.93x 10-3 M             c.  2.71

29.  Assume you have 0.50 M of HSO3-                   (Ka = 6.2 x 10-8)                            b.  1.76x 10-4 M             c.  3.75

30.  Assume you have 0.90 M of HclO              (Ka = 2.9 x 10-8)                   b.  1.62x 10-4 M             c.  3.79

 

For questions #31-35:  Using the following pH values, find the concentration of the acid in question.

You can use the Kas from the previous set of problems.

 

31.  pH = 3.00.  Find the [HF]                          1.52x 10-3 M

32.  pH = 4.00.  Find the [HCOOH]                 5.55x 10-5 M

33.  pH = 5.88.  Find the [CH3COOH]             9.65x 10-8 M

34.  pH = -0.86.  Find the [H2CO3]                   1.19x 108 M

35.  pH = 12.0.  Find the [HSO3-]                     1.61x 10-17 M

 

For Questions #36-40, Write the balanced equation for mixing these acids and bases together

                1.  Remember that Acid + Base ß-à  Salt + Water

 

36.  Hydrochloric Acid + Potassium Hydroxide

37.  Sulfuric Acid + Magnesium Hydroxide

38.  Sulfurous Acid + 1 mole of Sodium Hydroxide

39.  Hydrochloric Acid + Sodium Hydroxide

40.  Acetic Acid + Sodium Hydroxide

 

For Questions 41-45, you are going to titrate in a certain amount of base into each acid listed in the equations in #36-40.  Predict the exact amount of base (in mL) needed to neutralize each acid.

                1.  When you have an equal number of moles of acid in the reactant as you do base in the reactant, you can assume you have neutralized the pH.

 

41.  You have 100 mL of a 1.0 M solution of Hydrochloric acid.  How many mL of 0.05 M Potassium hydroxide will you need to add to neutralize the pH?   2,000mL

42.  You have 200 mL of a 2.5 M solution of Sulfuric acid.  How many mL of 1.0 M Magnesium hydroxide will you need to add to neutralize the pH?    500mL

43.  You have 275 mL of a 3.0 M solution of Sulfurous acid.  How many mL of 1.50 M Sodium hydroxide will you need to add to neutralize the pH?    550mL

44.  You have 380 mL of a 3.5 M solution of Hydrochloric acid.  How many mL of 3.00 M Sodium hydroxide will you need to add to neutralize the pH?      443.3mL

45.  You have 650 mL of a 4.0 M solution of Acetic acid.  How many mL of 2.50 M Sodium hydroxide will you need to add to neutralize the pH?       1,040mL

 

From the Book:  Don’t forget to do these.  This is where students lose points!

Problems 1-2 p. 503