MOCK FINALS APPCHEN QUESTIONS

Transcription

1 MOCK FINALS APPCHEN QUESTIONS For questions 1-3 Aluminum dissolves in an aqueous solution of NaOH according to the following reaction: 2 NaOH + 2 Al + 2 H2O 2 NaAlO2 + 3 H2 If 84.1 g of NaOH and 51.0 g of Al react: 1. Which is the limiting reagent? a. Sodium hydroxide b. Aluminum c. Water d. Hydrogen gas 2. How much of the other reagent remains? a g b g c g d g 3. What mass of hydrogen is produced? a g b g c g d g 4. When 15.3 g of sodium nitrate, NaNO3, was dissolved in water in a calorimeter, the temperature fell from C to C. If the heat capacity of the solution plus the calorimeter is 1071 J/ C what is the enthalpy change when one mole of NaNO3 dissolves? a kj/mol b kj/mol c.16.4 kj/mol d.19.3 kj/mol 5. If 10.0 kj of energy is added to a 15.5 g sample of water at 10 C, the water is. ΔHvap water = 40.7 kj/mol, ΔHfus water = 6.01 kj/mol a. Boiling b. Completely vaporized c. Frozen solid d. Still a liquid 6. If 100 ml of HCl gas at 300 K and 200 kpa dissolved in pure water requires ml of the NaOH solution to neutralize in a titration experiment, what is the concentration of the NaOH solution? a M

2 b M c M d M 7. A gas collected when the pressure is 107kPa and the temperature is 27 C has a volume of ml. What will the volume of the same amount of gas be at 26.6 F and 743 torr? a. 206 ml b. 540 ml c. 486 ml d. 513 ml 8. The reaction A products is second order in A. Initially [A] 0 = 1.00M; and after 25 mins, [A] = 0.25M. What is the rate constant for this reaction? a M -1 min -1 b M -1 min -1 c M -1 min -1 d M -1 min Which of the following is the INCORRECT statement? a. The oxidation number of chlorine atoms in Cl2 is zero. b. Oxidation results in an increase in oxidation number. c. The oxidizing agent in a redox reaction is reduced. d. Reduction is a loss of electrons How many grams of Ag(s) could be plated out on the cathode of an electrolytic cell by the passage of 5.0 Amps of current through AgNO3 solution for 1 hour? a. 5.5 x 10-3 g b g c. 5.2 x 10-5 g d. 20 g 11. An ideal gas has an initial volume of 20.0 L and final temperature of 298K. What is the final volume of the gas? a L b L c L d. Cannot be determined 12. A certain reaction proceeds as second order. What is the final concentration at t = 2s if the initial concentration is 2.58M? What is the half life if k = 0.002(Ms) -1? a M, 215s b M, 215s c M, 250s d M, 250s

3 13. What will be the final concentration of the reaction in no. 2 if it will proceed as zero order? a M b M c M d M 14. What is the ph of a solution containing 0.02 M HA and 0.01 M A -? pka of HA = 5.0. a b. 7.0 c. 2.6 d Which of the following is not true? a. A catalyst lowers the activation energy of the reaction. b. The reaction rate can be defined as the increase in the concentration of a product per unit time. c. The reaction rate can be defined as the decrease in the concentration of a reactant per unit time. d. A catalyst speeds up the reaction by completely consuming the catalyst which makes product formation more favorable. 16. A mol compound with the formula C n H 2n+2 is kept under a constant volume 2.0L. This compound has a density of 0.85g/L. What is the formula of the compound? a. CH 4 b. C 2 H 6 c. C 3 H 8 d. C 4 H Consider the reaction A B The rate of the reaction is 1.6 x 10-2 M/s, when the concentration of A is 0.35M. Calculate the rate constant if the reaction is first order in A. a s -1 b s -1 c Ms -1 d Ms What is the ph of a buffered solution of 0.5 M ammonia and 0.5 M ammonium chloride when enough hydrochloric acid is dissolved to make it 0.15 M HCl? The pk b of ammonia is a. 5.62

4 b c d How many kj are required to heat 45.0 g of H 2 O at 25.0 C and then boil it all away? Cp H2O = J /g C a. 116 kj b. 520 kj c. 84 kj d. 98 Kj 20. A 7.85 x 10-5 mol sample of copper-61 emits 1.47 x positrons in 90.0 minutes. What is the decay constant for copper-61? a min -1 b min -1 c min -1 d. Cannot be determined 21. A certain radioactive isotope is considered to be safe when the concentration drops to 0.195% of its original amount. if the concentration of a sample drops from 0.50 M to M in 1.00 years, how long (in years) will it take for the sample to be considered safe? a yrs b yrs c yrs d. 2.7 yrs 22. The radioisotope fluorine-21 had an initial mass of 80 milligrams. 20 milligrams of sample remained unchanged after 8.32 s. What is the half life of F-21? a.) 5.24s b.) 12.8s c.) 3.14s d.) 4.16s 23. The volume of a gas mixture is equal to the sum of the volumes of all constituents at the same temperature and pressure as the mixture. Which law pertains to this statement? a.) Amagat s Law b.) Charles Law c.) Graham s Law d.) Rate Law

5 24. is one whose rate depends on the concentration of a single reactant raised to the second power or on the concentrations of two different reactants, each raised to the first power. a.) First-order Reaction b.) Second-order Reaction c.) Third-order Reaction d.) Double Displacement Reaction Volt is equal to: a.) 1 J / C b.) 1 J / kg c.) 1 kj / s d.) 1 N / m Determine which of the following are true. If Ka is the dissociation constant of a weak acid and Kb is the dissociation constant of its conjugate base a. the bigger the Ka the smaller the Kb b. the smaller the Ka the smaller the Kb c. Ka/Kb = Kw d. both a and b 27. Molality is a. moles solute/kg solution b. moles solute/ kg solvent c. moles solute/ L solvent d. moles solute/ L solution 28. Which of the following salts would give a solution that is NOT neutral? a. NaCl b. NH 4 + Cl - c. Na + CH 3 COO - d. b and c The molar solubility of a generic substance, M(OH)2in 0.10 M KOH solution is 1.0 x 10-5mol/L. What is the Ksp for M(OH)2? a. 1.0x10-3 b. 1.0x10-4 c. 1.0x10-6 d. 1.0x The Kspfor silver carbonate is 8.4 x The concentration of carbonate ions in a saturated solution is 1.50x 10-4M. What is the concentration of silver ions? a. 1.54x10-2 M b. 1.18x10-4 M c. 2.37x10-4 M d. 3.55x10-8 M

6 ANSWERS 1. B 2. A 3. D 4. B 5. A 6. C 7. C 8. C 9. D 10. D 11. D 12. C 13. C 14. D 15. D 16. B 17. A 18. D 19. A 20. B 21. D 22. D 23. A 24. B 25. A 26. A 27. B 28. D 29. D 30. C