MC_Chem1B_Sp09_LabQuiz2

Multiple Choice
Identify the choice that best completes the statement or answers the question.

____	1.	An aqueous solution with a pH of 3.00 is diluted from 2.0 L to 4.0 L. What is the pH of the diluted solution?
a.	1.50	
b.	1.73	
c.	3.00	
d.	3.30	
e.	6.00	

____	2.	Which of the following half-reactions has been assigned a standard reduction potential, E°, of 0.00 Volts?
a.	2 H2O(l) + 2 e- ® H2(g) + 2 OH-(aq)	
b.	O2(g) + 4 e- ® 2 O2-(aq)	
c.	Hg2Cl2(s) + 2 e- ® 2 Hg(l) + 2 Cl-(aq)	
d.	Li+(aq) + e- ® Li(s)	
e.	2 H+(aq) + 2 e- ® H2(g)	

____	3.	If the pH of a 0.1 M acid is 5.2, the pKa of the acid is:
a.	-9.4	b.	9.4	c.	3.5	d.	11.6	e.	5.5	

____	4.	When 10mL of a 0.1 M BaCl2 solution is mixed with 10mL of 0.1M NaIO3 solution,which ion in what concentration would still be present in the equlibrium solution after precipitate of Ba(IO3)2 is formed? Assume Ksp of Ba(IO3)2 to be very low.
a.	0.25 M Ba2+	b.	0.025 M Cl-	c.	0.1 M IO3-	d.	0.1 M Na+	e.	0.025 M Ba2+	

____	5.	In testing unknown solution for Group III cations, a student boiled the mixture with 6M NaOH and H2O2 solution for a minute and then with NH3 solution for another minute. When the solution was then centrifuged, a colored precipitate remained and the supernate was yellow in color. The unknown solution may contain the following ions:
a.	Fe3+, Ni2+	b.	Ni2+	c.	Cr3+	d.	Cr3+, Al3+	e.	 Al3+	

____	6.	You need to make a buffer solution by mixing an 0.1 M unknown acid (Ka = 1.8 x10-4) and 0.1 M NaOH solutions. How many  milliliter (mL) of the NaOH solution would you add to 20.0mL of the acid to prepare a buffer of pH = 3.4?
a.	19.9	b.	9.0	c.	3.4	d.	1.2	e.	6.2	

____	7.	Which of the following combinations would be best to buffer an aqueous solution at a pH of 2.0?
a.	H3PO4 and H2PO4-, Ka1 = 7.5 ´ 10-3	
b.	HNO2 and NO2-, Ka = 4.5 ´ 10-4	
c.	CH3CO2H and CH3COO-, Ka = 1.8 ´ 10-5	
d.	H2PO4- and HPO42-, Ka2 = 6.2 ´ 10-8	
e.	NH4+ and NH3, Ka = 5.7 ´ 10-10	

____	8.	What is the pH of a buffer that results when 33 g NaHCO3 is mixed with 100.0 mL of 2.50 M NaOH and diluted with water to 250 mL? (Ka for HCO3- = 4.8 ´ 10-11)
a.	8.20	
b.	10.07	
c.	10.12	
d.	10.32	
e.	10.56	

____	9.	The Ksp of AgBr is 5.4 ´ 10-13 at 25 °C. Calculate the molar solubility of AgBr in 0.015 M NaBr(aq) at 25 °C.
a.	8.1 ´ 10-15 mol/L	
b.	3.6 ´ 10-11 mol/L	
c.	1.1 ´ 10-8 mol/L	
d.	7.3 ´ 10-7 mol/L	
e.	4.9 ´ 10-5 mol/L	

____	10.	At 15 °C, the water ionization constant, Kw, is 4.5 ´ 10-15. What is the H3O+ concentration in neutral water at this temperature?
a.	2.0 ´ 10-29 M	
b.	4.5 ´ 10-15 M	
c.	6.7 ´ 10-8 M	
d.	1.5 ´ 10-7 M	
e.	2.2 M	

____	11.	Which one of the following aqueous solutions will have a pH of 10.00 at 25 °C? (Kw = 1.0 ´ 10-14)
a.	1.0 ´ 101 M HCl	
b.	1.0 ´ 102 M HNO3	
c.	1.0 ´ 10-4 M HBr	
d.	1.0 ´ 10-4 M NaOH	
e.	1.0 ´ 102 M KOH	

____	12.	Which salt forms a 0.10 M aqueous solution with the lowest pH?
a.	MgCO3	
b.	NaCl	
c.	NaF	
d.	NH4Cl	
e.	K3PO4	

____	13.	The following reaction occurs spontaneously.

2 H+(aq) + Ca(s) ® Ca2+(aq) + H2(g)

Write the balanced reduction half-reaction.
a.	2 H+(aq) + 2 e- ® H2(g)	
b.	2 H+(aq) ® H2(g) + 2 e-	
c.	H2(g) ® 2 H+(aq) + 2 e-	
d.	Ca(s) + 2 e- ® Ca2+(aq)	
e.	Ca(s) ® Ca2+(aq) + 2 e-	

____	14.	Write a balanced half-reaction for the reduction of ClO3-(aq) to Cl2(g) in an acidic solution.
a.	2 ClO3-(aq) + 6 H+(aq) + 10 e- ® Cl2(g) + 6 OH-(aq)	
b.	2 ClO3-(aq) + 12 H+(aq) + 5 e- ® Cl2(g) + 6 H2O(l)	
c.	2 ClO3-(aq) + 10 e- ® Cl2(g) + 6 H2O(l) + 3 O2(g)	
d.	2 ClO3-(aq) + 12 H+(aq) + 10 e- ® Cl2(g) + 6 H2O(l)	
e.	2 ClO3-(aq) + 18 H+(aq) ® Cl2(g) + 6 H3O+(aq)	

____	15.	Use the standard reduction potentials below to determine which element or ion is the best oxidizing agent.

Br2(l) + 2 e- ® 2 Br-(aq) E° = +1.08 V
Hg2+(aq) + e- ® Hg(l) E° = +0.86 V
Ni2+(aq) + 2 e- ® Ni(s) E° = -0.25 V

a.	Br2	
b.	Br-	
c.	Hg2+	
d.	Ni2+	
e.	Ni	

____	16.	Consider the following half-reactions:

F2(g) + 2 e- ® 2 F-(aq) E° = +2.87 V
Cu2+(aq) + 2 e- ® Cu(s) E° = +0.34 V
Sn2+(aq) + 2 e- ® Sn(s) E° = -0.14 V
Al3+(aq) + 3 e- ® Al(s) E° = -1.66 V
Na+(aq) + e- ® Na(s) E° = -2.71 V

Which of the above elements or ions will oxidize Sn(s)?
a.	Cu(s) and Al3+(aq)	
b.	F-(aq) and Cu(s)	
c.	F2(g) and Cu2+(aq)	
d.	Al(s) and Na(s)	
e.	Al3+(aq) and Na+(aq)	

____	17.	To titrate 100 mg of ascorbic acid in water, 23.52 mL of an iodine solution of unknown strength is needed to reach starch end point. What is the molarity (M) of iodine solution?
a.	4.84x10-2	b.	1.21x10-3	c.	1.21x10-2	d.	2.42x10-2	e.	2.42x10-3	

____	18.	If 100 mL of an orange juice needed 9.58 mL of 0.0242 M iodine solution to reach starch end point, then what is the concentration of vitamin C in the orange juice expressed as mg vitamin C per 100 mL of the juice (mg/100mL)?
a.	8.19x10+1	b.	4.07x10+3	c.	4.07x10-1	d.	4.07x10+1	e.	4.07x10-3	

MC_Chem1B_Sp09_LabQuiz2
Answer Section

MULTIPLE CHOICE

	1.	ANS:	D	PTS:	1	OBJ:	17.3 Water and the pH Scale

	2.	ANS:	E	PTS:	1	OBJ:	20.4 Standard Electrochemical Potentials

	3.	ANS:	B	PTS:	1

	4.	ANS:	E	PTS:	1

	5.	ANS:	D	PTS:	1

	6.	ANS:	E	PTS:	1

	7.	ANS:	A	PTS:	1	OBJ:	18.2 Controlling pH: Buffer Solutions

	8.	ANS:	E	PTS:	1	OBJ:	18.2 Controlling pH: Buffer Solutions

	9.	ANS:	B	PTS:	1	OBJ:	18.4 Solubility of Salts

	10.	ANS:	C	PTS:	1	OBJ:	17.3 Water and the pH Scale

	11.	ANS:	D	PTS:	1	OBJ:	17.3 Water and the pH Scale

	12.	ANS:	D	PTS:	1	OBJ:	17.4 Equilibrium Constants for Acids and Bases

	13.	ANS:	A	PTS:	1	OBJ:	20.1 Oxidation-Reduction Reactions

	14.	ANS:	D	PTS:	1	OBJ:	20.1 Oxidation-Reduction Reactions

	15.	ANS:	A	PTS:	1	OBJ:	20.4 Standard Electrochemical Potentials

	16.	ANS:	C	PTS:	1	OBJ:	20.4 Standard Electrochemical Potentials

	17.	ANS:	D	PTS:	1

	18.	ANS:	D	PTS:	1