CHAPTER 17 		

1. (3 pts.)  When the following salts are dissolved in 
	water, predict whether the resulting solution 
	will be acidic (A), basic (B), or neutral (N).

A   B	N	a. KCN (Ka for HCN = 4.9 x 10-10)

A   B	N	b. NaNO3

A   B	N	c. CH3NH3Cl (Kb for CH3NH2 = 4.4 x 10-4)


2. (3 pts.)  Calculate the Ka for HCN if the pH of a 1.5 M solution 
	is 4.60.









3. (3 pts.)  Calculate the pH of a 0.75 M solution of NH3.

	[Kb for NH3 = 1.8 x 10-5]




4. (3 pts.)  Circle T (true) or F (false):

T  F  a. The pH of a 0.1 M solution of HNO3 is 1.

T  F  b. The acetate ion is a stronger base than water.

T  F  c. The compound C5H5N is an example of a weak acid.

5. (1 pt.)  What is the conjugate base of NH3?_______________


6. (1 pt.)  What is the conjugate acid in the following reaction?

H-(aq) + H2O(g) ---> H2(g) + OH-(aq)___________________________

7. (4 pts.)  Calculate [H+] in a 0.10 M NaBrO solution.

		(Ka for HBrO is 2.0 x 10-9)

















8. (2 pts.)  Write an equation for the reaction of each in water.

a. NaC7H5O2__________________________________________________



b.HNO2__________________________________________________


			KEY		
1. (3 pts.)  When the following salts are dissolved in water, 
	predict whether the resulting solution will be acidic 
	(A), basic (B), or neutral (N).

 A  (B)	 N	a. KCN (Ka for HCN = 4.9 x 10-10)  

			   (CN- is conjugate base.)

 A   B  (N)	b. NaNO3(NO3- is anion of strong acid; not basic.)

(A)  B	 N	c. CH3NH3Cl (Kb for CH3NH2 = 4.4 x 10-4)

		(CH3NH3+ is similar to NH4+; acidic)


2. (3 pts.)  Calculate the Ka for HCN if the pH of a 1.5 M solution 
	is 4.60.

pH = 4.60		HCN ---> H+ + CN-		Ka = [H+][CN-]/[HCN]
										   
[H+] = 2.5 x 10-5 M = [CN-]     [HCN] = 1.5 M
  
Ka = (2.5 x 10-5)2/ 1.5 M = 4.2 x 10-10
						


3. (3 pts.)  Calculate the pH of a 0.75 M solution of NH3.

	[Kb for NH3 = 1.8 x 10-5]


	NH3 + H2O ---> NH4+	+ OH-

Initial	0.75		 0	   0

Change	 -x 		 x  	   x 

Equil.	0.75-"x"         x	   x

Ignore "x" in the 0.75 - "x" term because "x" is small(insignificant) compared to 0.75!!

Kb = [NH4+][OH-]/[NH3] = 1.8 x 10-5

Kb =  x2/0.75  = 1.8 x 10-5

x2 = 1.35 x 10-5

x = 3.7 x 10-3 M = [OH-]

pOH = 2.43

pH = 14 - 2.43

pH = 11.57

4.	(3 pts.)  Circle T (true) or F (false):

"T"  F  a. The pH of a 0.1 M solution of HNO3 is 1.  

		(HNO3 is a strong acid.)

"T"  F  b. The acetate ion is a stronger base than water.

 T  "F"  c. The compound C5H5N is an example of a weak acid.

5. (1 pt.)  What is the conjugate base of NH3?	  NH2-  

		NH3 ---> NH2- + H+


6. (1 pt.)  What is the conjugate acid in the following reaction?

	H-(aq) + H2O(g) ---> H2(g) + OH-(aq)	  H2  
	base     acid	     C.A.    C.B.


7. (4 pts.)  Calculate [H+] in a 0.10 M NaBrO solution.
  (Ka for HBrO is 2.0 x 10-9)	Kb =Kw/Ka=1.0 x 10-14/2.0 x 10-9
		

	BrO- + H2O ---> HBrO  +    OH-
I	0.10 M		  0	   0
C	  -x              x 	   x 
E	0.10 - "x"        x	   x

Ignore "x" in the 0.10 - "x" term because "x" is small(insignificant) compared to 0.10!!

Kb = [HBrO][OH-]/[BrO-] = 5.0 x 10-6

  x2/0.10  = 5.0 x 10-6; 

x = 7.1 x 10-4 M = [OH-]

[H+]/[OH-] = Kw = 1.0 x 10-14/7.1 x 10-4 =

1.4 x 10-11M

8.(2 pts.)  Write an equation for the reaction of each in water.

WB 	a. NaC7H5O2 BASIC	  C7H5O2- + H2O ---> HC7H5O2 + OH-  

WA	b. HNO2 ACIDIC		  HNO2 ---> H+  +  NO2-