Chemistry: Molecular Nature of Matter and Change, 6th Edition (Silberberg)

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1			A buffer is prepared by dissolving 4.00 g benzoic acid (C6H5COOH, Ka = 6.3 x 10-5) and 4.00 g sodium benzoate (C6H5COONa) in enough water to prepare 1.00 L of solution. Calculate the pH of this buffer.
			A)	4.13
			B)	4.20
			C)	4.27
			D)	4.40
			E)	5.05
2			Calculate the [NH3]/[NH4+] ratio in an ammonia-ammonium chloride buffer with a pH of 9.00. (Kb for NH3 = 1.8 x 10-5)
			A)	0.56/1.00
			B)	0.74/1.00
			C)	0.86/1.00
			D)	1.12/1.00
			E)	1.30/1.00
3			A buffer is prepared by adding 0.30 mol CH3COONa to 2.0 L of a 0.10 M CH3COOH solution. Calculate the pH after 0.030 mol HCl are added to the buffer. (Ka for CH3COOH = 1.8 x 10-5)
			A)	1.52
			B)	3.57
			C)	4.81
			D)	5.13
			E)	6.34
4			What is the pH of a buffer prepared by adding 180 mL of 0.100 M NaOH to 200 mL of 0.100 M acetic acid? (Ka for CH3COOH = 1.8 x 10-5)
			A)	3.79
			B)	4.34
			C)	4.74
			D)	5.04
			E)	5.70
5			Consider the titration of 50.00 mL of 0.1000 M HBr with 0.1000 M KOH. Calculate the pH after 49.00 mL of the base has been added to the 50.00 mL of HBr.
			A)	2.0
			B)	3.0
			C)	4.0
			D)	6.0
			E)	7.0
6			Calculate the pH at the equivalence point for the titration of 0.20 M aniline (C6H5NH2) with 0.20 M HCl. (Kb for aniline = 3.8 x 10-10)
			A)	2.6
			B)	2.8
			C)	5.2
			D)	9.4
			E)	11.1
7			Citric acid, H3C6H5O7, is a triprotic acid, with Ka1 = 7.5 x 10-4, Ka2 = 1.7 x 10-5, and Ka3 = 4.0 x 10-7. 1.00 x 10-3 mol of aqueous citric acid is titrated with 0.100 M NaOH. Predict the pH of the titration mixture after the addition of 15.0 mL of the NaOH solution.
			A)	2.68
			B)	3.12
			C)	3.95
			D)	4.77
			E)	6.40
8			An aqueous solution of a weak acid, HA, is titrated with NaOH solution. The pH at the midpoint of the buffer region is 4.5. What is the Ka of the acid?
			A)	3.2 x 10-5
			B)	3.2 x 10-10
			C)	1.8 x 10-3
			D)	7.0 x 10-7
			E)	4.5
9			Which of the following best describes the acid/base properties of normal rainwater, in the absence of any man-made pollutants?
			A)	very acidic
			B)	slightly acidic
			C)	neutral
			D)	slightly basic
			E)	may be basic or acidic
10			Given that the solubility of Ag2CrO4 is 0.0287 g/L, what is the value of its Ksp?
			A)	Ksp = 3.9 x 10-17
			B)	Ksp = 6.5 x 10-13
			C)	Ksp = 8.7 x 10-5
			D)	Ksp = 7.5 x 10-9
			E)	Ksp = 2.6 x 10-12
11			The solubility of AlF3 is 6.7 g AlF3 per liter of solution. What is the value of the solubility product constant for AlF3?
			A)	1.9 x 10-2
			B)	6.0 x 10-3
			C)	1.1 x 10-3
			D)	4.0 x 10-4
			E)	4.1 x 10-5
12			How many grams of AgCl will dissolve in 1.0 L of water? (Ksp for AgCl = 1.7 x 10-10)
			A)	1.2 x 10-12 g
			B)	2.4 x 10-8 g
			C)	4.5 x 10-5 g
			D)	1.8 x 10-3 g
			E)	1.4 x 10-2 g
13			Calculate the pH of a solution necessary to just begin the precipitation of Mg(OH)2 when [Mg2+] = 0.001 M. (Ksp for Mg(OH)2 = 1.2 x 10-11)
			A)	11
			B)	10
			C)	9
			D)	8
			E)	4
14			In qualitative analysis, the metals of Ion Group 1 can be separated from other ions by precipitating them as chloride salts. A solution initially contains Ag+ and Pb2+ at a concentration of 0.10 M. Aqueous HCl is added to this solution until the Cl- concentration is 0.10 M. What will the concentrations of Ag+ and Pb2+ be at equilibrium? (Ksp for AgCl = 1.8 x 10-10; Ksp for PbCl2 = 1.7 x 10-5)
			A)	[Ag+] = 1.8 x 10-11 M; [Pb2+] = 1.7 x 10-6 M
			B)	[Ag+] = 1.8 x 10-7 M; [Pb2+] = 1.7 x 10-4 M
			C)	[Ag+] = 1.8 x 10-11 M; [Pb2+] = 8.5 x 10-5 M
			D)	[Ag+] = 1.8 x 10-9 M; [Pb2+] = 1.7 x 10-3 M
			E)	[Ag+] = 1.8 x 10-9 M; [Pb2+] = 8.5 x 10-6 M
15			Silver chloride is relatively insoluble in water (Ksp for AgCl = 1.8 x 10-10) but it is soluble in aqueous ammonia, due to the formation of the complex ion Ag(NH3)2+. How many moles of AgCl will dissolve in 1.00 L of solution containing 6.0 moles of free NH3? (Kf for Ag(NH3)2+ = 1.7 x 107)
			A)	9.1 x 10-6 mol
			B)	2.9 x 10-4 mol
			C)	0.0091 mol
			D)	0.084 mol
			E)	0.33 mol