Chemistry I Practice Exam

Transcription

1 Chemistry I Practice Exam Name Multiple Choice: Choose the best answer that completes each statement. Put all answers on your answer sheet. 1. The mass of one mole of NaCl is a..53 g b g c g d g 2. The molar mass for Mn(NO 3 ) 2 is a g b g c g d g 3. Which of the following is equal to one mole of any substance? a x b x c x d x ow many moles are in.0 g of CO 2? a. 0.5 b. 1.0 c. 1.5 d ow many grams are in 2.35 moles of ZnCl 2? a. 136 g b. 320 g c g d. 6.0 g 6. ow many moles of P are in 2.4 x atoms of P? a. 1.0 b. 2.0 c. 3.0 d Which of the following contain equal number of atoms? a. 47. g Ti and g Zn c g Ti and g Zn b. 22 g Ti and 30 g Zn d. 47. moles Ti and moles Zn. The relative amounts of the elements in a compound are expressed as the? a. empirical formula c. limiting reactant b. percent composition d. theoretical yield 9. A formula with the lowest whole-number ratio of elements in a compound a. empirical formula c. ionic formula b. molecular formula d. covalent formula

2 10. At STP, 1 mol of any gas occupies what volume? a L b. 22.4L c L d. 146 L 11. If the empirical formula of a compound is C, then a molecular formula of this compound could be a. C 4 b. C 2 c. C 2 4 d. C The percent composition of carbon in acetone, C 3 6 O, is a b c d The empirical formula of a compound is C 2 F. The molecular weight of this compound is 66.0 g. The molecular formula of the compound is: a. C 4 F 4 b. C 4 4 F 4 c. C 2 4 F 2 d. C 2 F 14. The data table below gives the temperature and pressure of four different gas samples, each in a 2-liter container. Temperature and Pressure of Gas Samples Gas Sample Temperature Pressure (K) (atm) e Ne CO C Which two gas samples contain the same total number of particles? a. C4 and CO2 b. e and CO2 c. C4 and Ne d. e and Ne 15. The percent composition by mass of magnesium in MgBr2 (molar mass = 14 grams/mole) is equal to 24 a. x b. x 100 c. x 100 d. x Given the balanced equation representing the reaction between propane and oxygen: C 3 + 5O 2 3CO O According to this equation, which ratio of oxygen to propane is correct? a. 5gO2 1gC 3 b. 5molO2 1molC 3 c. 10gO2 11gC 2 d. 10molO2 11molC The substance that controls the quantity of product that can be formed in a chemical reaction is a. limiting reactant c. actual yield b. theoretical yield d. percent yield

3 1. The maximum amount of product supposed to be formed from a chemical reaction. a. limiting reactant c. actual yield b. theoretical yield d. percent yield 19. Given the balanced equation representing a reaction: F2(g) + 2(g) 2F(g) What is the mole ratio of 2(g) to F(g) in this reaction? a. 1:1 b. 1:2 c. 2:1 d. 2:3 20. Given the balanced equation representing a reaction: 4N3 + 5O2 4NO + 62O What is the minimum number of moles of O2 that are needed to completely react with 16 moles of N3? a. 16 mol b. 20. mol c. 64 mol d. 0. mol 21. The equation for the production of chalk, calcium carbonate is the following CaCl 2 + Na 2 CO 3 CaCO NaCl When 1.00 mole of CaCl 2 reacts with 2.00 mole of Na 2 CO 3 which of the following acts as the limiting reactant? a. CaCl 2 b. Na 2 CO 3 c. CaCO 3 d. NaCl 22. Using the following equation find the number of grams of calcium hydroxide which can be produced starting with 25.0 grams of calcium nitride. Ca 3 N 2 (s) O (l) 3 Ca(O) 2 (s) + 2 N 3 a g b g c g d g 23. According to the equation, N 2 O 3 (g) (g) 2N 3 (g) O(g) how many moles of N 3 (g) could be formed from the reaction of 0.22 mol of N 2 O 3 (g) with 0.7 mol of 2 (g)? a mol b mol c mol d. 1.1 mol Use the following information and balanced equation to answer the next four questions. An important equation used to produce ammonia is as follows: N 2 (g) (g) 2 N If 56.0 g of nitrogen is reacted with 15.0 g hydrogen which substance is the limiting reactant? a. N 2 c. N 3 b. 2 d. 2 O

4 25. Calculate the number of grams of reactant in excess. a g b g c g d g 26. What is the theoretical yield of N 3? a g b g c. 6.0 g d. 5.0 g 27. The actual yield of N 3 from this reaction is 33.5 g, what is the percent yield? a. 39.4% b. 49.3% c. 67.0% d. 9.5% 2. For a gas with temperature and number of moles are held constant, Boyle s law describes a situation in which: a. volume and pressure have no relationship b. volume increases with increasing pressure c. volume decreases with decreasing speed d. volume decreases with increasing pressure 29. The letters STP stand for: a. solid, time, and pressure b. solid, temperature and pressure c. standard time and pressure d. standard temperature and pressure 30. The tendency of molecules to move towards areas of lower concentration until the concentration is uniform throughout. a. diffusion b. effusion c. ideal gas d. pressure 31. As the temperature of a fixed volume of gas increases, the pressure will a. vary inversely b. decrease c. be unchanged d. increase 32. A gas has a volume of 300 ml at a pressure of 105 kpa. The volume at standard pressure is a. 57 ml b. 105 ml c. 311 ml d. 29 ml 33. Oxygen gas at 293 K and 100. kpa occupies 500.mL What volume will the gas occupy at 303 K if the pressure does not change. a. 471 ml b. 43 ml c. 503 ml d. 517 ml 34. The ideal gas law states that: P V a. = nrt b. = nrt c. PV = nrt d. PT = nrv V P 35. What volume will 10.0 g of Ne occupy at STP? a..21 L b L c L d. 44. L

5 36. Which of the following gas molecules have the greatest average velocity (speed)? a. CO 2 b. N 3 c. Cl 2 d. CN 37. Calculate the partial pressure of oxygen gas is a mixture of three gases, O 2, N 2, and CO 2, when the total pressure is 100 kpa and the sum of the partial pressures of N 2 and CO 2 is 50 kpa. a. 25 kpa b. 50 kpa c. 75 kpa d. 100 kpa 3. A real gas will behave ideally at a. low temperatures and low pressures b. low temperatures and high pressures c. high temperatures and low pressures d. high temperatures and high pressures 39. All of the following statements are basic assumptions of the kinetic theory except: a. gas molecules travel in a perfectly chaotic motion b. gas molecules in an ideal gas have no volume c. gas molecules in an ideal gas do not exert attractive forces d. collisions between particles are perfectly elastic e. the kinetic energy of the gas is proportional to the temperature 40. At which temperature would e have the greatest kinetic energy? a. 25 o C b. 37 o C c. 273 K d. 29 K 41. ow many total moles of KNO 3 must be dissolved in water to make 1.5 liters of a 2.0 M solution? a mol b. 2.0 mol c. 3.0 mol d. 1.3 mol 42. Which of the following is soluble? a. CaCl 2 b. BaSO 4 c. AgBr d. Al(O) Which of the following is insoluble? a. NaCl b. KNO 3 c. CoSO 4 d. CaCO The concentration of a solution in moles per liter is called its. a. molar mass b. molarity c. volume mass d. ppm 45. ow many grams are needed to prepare 500 ml of a 2.50 M NaCl solution? a g b. 5.5g c g d. 146 g

6 46. What is the total amount of heat required to vaporize 1.00 g of 2 O (l) at 100 o C and 1 atm. vap = 40.7kJ/mol a. 4.1 J b. 334 J c. 373 J d J The potential energy diagram for the reaction of carbon and hydrogen is shown to the right with the reaction below: 2 C (s) + 2 2(g) kj C 2 4(g) 47. Which section of the diagram represents the rxn? b d 4. Which section represents the activation energy? c 49. Calculate the amount of energy required to form 2.0 moles of C 2 4. a kj c kj b kj d kj a. 50. The diagram represents. a. an exothermic reaction where energy is released b. an exothermic reaction where energy is absorbed c. an endothermic reaction where energy is released d. an endothermic reaction where energy is absorbed 51. What is required for a chemical reaction to occur? a. standard temperature and pressure c. effective collisions between reactant particles b. a catalyst added to the reaction system d. an equal number of moles of reactants and products 52. Increasing the temperature of a liquid solvent when dissolving a solid solute a. always increases the rate at which a solid solute dissolves b. often increases the amount of solid solute that can dissolve c. both a and b d. neither a and b 53. Which equation represents the radioactive decay of 226 Ra by an alpha emission? a Ra Rn b Ra Ac e c. Ra Fr + 0 e e d. Ra Ra + 1 n 0

7 54 Beta particles are: a. rapidly moving helium nuclei b. electromagnetic radiation more energetic than X-rays c. electrons which move at tremendous speeds d. particles with the same mass as an electron but has a positive charge 55. Given the diagram representing a reaction: Which phrase best describes this type of reaction and the overall energy change that occurs? a. fission and energy is released c. fusion and energy is released b. fission and energy is absorbed d. fusion and energy is absorbed Given the nuclear equation: 99 Es + X 1 n Md which particle represents X? 4 a. 2 e b. 0 1e c. 1 n d. 0 e If 1 of an original sample of Kr-74 remains after 34.5 minutes, what is the half life of Kr-74? a minutes b minutes c minutes d minutes 5. Nuclear fusion a. takes place in the sun c. produces nonradioactive products b. is when two smaller nuclei form a larger nuclei d. all of the above 59. Iodine-131 has a half-life of days. If the amount of iodine-131 in a sample is 64.0g, how much will remain after 40 days? a g b..0 g c. 4.0 g d. 2.0 g 60. Which of the following is true concerning gamma radiation? a. The mass number of the radioisotope decreases by four. b. The atomic number of the radioisotope decreases by two. c. The atomic number of the radioisotope increases by one. d. Neither the mass number nor the atomic number changes.