Chemistry 1A Fall 2013 MWF 9:30 Final Test Form A

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1 Chemistry 1A Fall 2013 MWF 9:30 Final Test Form A 1. How many moles of P 4 molecules are in g of phosphorus? A) mol B) x10 4 mol C) mol D) x 10 1 mol E) x 10 1 mol 2. The empirical formula of sugar is CH 2 O and its molar mass is g/mole. If one teaspoon of sugar weighs 3.50 g, how many moles of sugar and how many molecules of sugar are present? A) mole, 7.03 x molecules B) mole, 3.24 x molecules C) mole, 1.17 x molecules D) mole, 3.51 x molecules E) mole, 1.78 x molecules 3. The empirical formula of a group of compounds is CHCl. Lindane, a powerful insecticide, is a member of this group. The molar mass of lindane is How many atoms of carbon does a molecule of lindane contain? A) 2 B) 3 C) 4 D) 6 E) 8 4. How much water must be added to 20.0 ml of a 9.50 M sulfuric acid solution to make a M solution? (Assume volumes are additive.) A) 81.0 ml B) 101 ml C) 376 ml D) 396 ml 5. The following reaction occurs in aqueous acid solution: NO 3 + I! IO 3 + NO 2 In the balanced equation, what is the coefficient of NO 3? A) 2 B) 3 C) 4 D) 5 E) 6 6. The volume of a balloon is 2.74 L at 24.3 C. The balloon is heated to 43.8 C. Calculate the new volume of the balloon. A) 4.94 L B) 2.92 L C) 1.52 L D) 2.57 L E) 2.74 L

2 7. Which gas has the highest density? All gases are at the same temperature and pressure. A) He B) Cl 2 C) CH 4 D) NH 3 E) All the gases have the same density. 8. For which gas do the molecules have the smallest average kinetic energy? A) He B) Cl 2 C) CH 4 D) NH 3 E) The molecules of all the gases have the same average kinetic energy. 9. At a certain temperature, K = 1.0 x 10-4 for the following reaction. N 2 (g) + O 2 (g) 2 NO(g) N 2 and O 2 are both at initial concentrations of 2.5 M. Calculate the concentration of NO after the system reaches equilibrium. A) M B) M C) M D) 1.56 x 10-4 M E) 4.0 M moles of HCl are added to 1.0 L of pure H 2 O. What is the ph? A) 9.0 B) 6.0 C) 7.0 D) The equilibrium constant for the reaction A + H + is given by A) K a B) K b C) K w K a D) HA E)

3 12. The conjugate base of a weak acid is A) a strong base. B) a weak base. C) a strong acid. D) a weak acid. 13. Given that the K a for HOCl is , calculate the K value for the reaction of HOCl with OH, specifically HOCl + OH H 2 O + OCl A) B) C) D) At a particular temperature, the ion-product constant of water, K w, is What is the ph of pure water at this temperature? A) 7.00 B) 6.82 C) 6.26 D) 7.18 E) Calculate [H + ] in a solution that has a ph of 9.7. A) 4 M B) 10 M C) M D) M E) M 16. Find the ph of a solution at 25 C in which [OH ] = M. A) 8.60 B) 5.40 C) 7.40 D) 6.50 E) Calculate the ph of a 1.9 M solution of HNO 3. A) 0.28 B) 0.64 C) 0.28 D) E) For nitrous acid, HNO 2, K a = Calculate the ph of 0.27 M HNO 2. A) 1.98 B) 0.57 C) 2.83 D) 4.54 E) 3.40

4 19. The ph of a M weak acid solution is Calculate K a for this acid. A) B) C) D) E) Calculate [H + ] in a M solution of HCN, K a = A) M B) M C) M D) M E) M 21. In a solution prepared by dissolving mol of propionic acid in enough water to make 1.00 L of solution, the ph is observed to be What is K a for propionic acid (HC 3 H 5 O 2 )? A) B) C) D) Calculate the poh of a 0.70 M solution of acetic acid (K a = ) at 25 C. A) 2.45 B) 9.26 C) 2.72 D) E) Calculate the ph of a solution made by a mixture of the following acids: 0.40 M HC 2 H 3 O 2 (K a = ), 0.10 M HOCl (K a = ), and 0.20 M HCN (K a = ). A) 2.57 B) 3.49 C) 3.92 D) 4.23 E) Which of the following reactions is associated with the definition of K b? 2+ A) Zn(OH 2 ) 6 [Zn(OH 2 ) 5 OH] + + H + B) CN + H + HCN C) F + H 2 O HF + OH D) Cr H 2 O 3+ Cr(OH 2 ) 6

5 25. Calculate the ph of a M solution of KOH. A) 1.32 B) 2.68 C) D) Calculate [H + ] in a solution that is 0.24 M in NaF and 0.46 M in HF. (K a = ) A) 0.46 M B) M C) M D) M E) M 27. For ammonia, K b is To make a buffered solution with ph 10.0, the ratio of NH 4 Cl to NH 3 must be A) 1.8 : 1. B) 1 : 1.8. C) 0.18 : 1. D) 1 : Calculate the ph of a solution prepared by mixing 50 ml of a 0.10 M solution of HF with 25 ml of a 0.20 M solution of NaF. pk a of HF is A) 5.83 B) C) 3.14 D) 7.35 E) How much solid NaCN (M.W. = 49.0 g/mol) must be added to 1.0 L of a 0.5 M HCN solution to produce a solution with ph 7.0? K a = for HCN. A) g B) 11 g C) 160 g D) 24 g E) 0.15 g 30. How many moles of HCl(g) must be added to 1.0 L of 2.0 M NaOH to achieve a ph of 0.00? (Neglect any volume change.) A) 3.0 mol B) 2.0 mol C) 1.0 mol D) 10. mol

6 31. A solution contains 0.34 M HA (K a = ) and 0.17 M NaA. Calculate the ph after 0.05 mol of NaOH is added to 1.00 L of this solution. A) 6.82 B) 6.40 C) 6.58 D) 6.19 E) Calculate the ph at the equivalence point for the titration of 1.0 M ethylamine, C 2 H 5 NH 2, by 1.0 M perchloric acid, HClO 4, which is a strong acid. (pk b for C 2 H 5 NH 2 = 3.25) A) 6.05 B) 2.24 C) 5.53 D) 2.09 E) Silver chromate, Ag 2 CrO 4, has a K sp of Calculate the solubility, in moles per liter, of silver chromate. A) M B) M C) M D) M E) M 34. What is the molar solubility of AgCl (K sp = ) in M sodium chloride at 25 C? A) B) C) D) Calculate the solubility of Cu(OH) 2 in a solution buffered at ph = (K sp = ) A) M B) M C) M D) M