South Pasadena AP Chemistry Name 10 States of Matter Period Date UNIT TEST PRACTICE The following formulas may be helpful. v rms = 3 R T MM v A v B = MM B MM A Part 1 Multiple Choice You should allocate 25 minutes to finish this portion of the test. No calculator should be used. A periodic table and data table will be provided. Select the answer that best responds to each question. 1. A crystalline solid displays the following properties: Has a melting point of 775 C. Does not conduct electricity as a solid. Is soluble in water. Which of the following could be this solid? (A) CaCl 2 (B) Diamond (C) Zn (D) P 4O 10 4. Consider the compounds, SO 2, CO 2, PbO 2. When listed in order of increasing strength of interparticle forces, the list would be (A) CO 2 < SO 2 < PbO 2 (B) PbO 2 < CO 2 < SO 2 (C) SO 2 < PbO 2 < CO 2 (D) CO 2 < PbO 2 < SO 2 2. Boron is introduced into a crystal of silicon, which allows the silicon to significantly increase its electrical conductivity. Which of the following explains this result? (A) Boron has a sea of electrons that allows silicon to conduct electricity better. (B) Boron has fewer valence electrons than silicon, which creates positive holes that can be filled to conduct electricity. (C) Boron has more valence electrons than silicon, so the excess electrons allow the material to conduct electricity better. (D) Boron s electronegativity is high, so it pulls electrons more strongly than silicon. 3. Which of the following substances would be expected to have the highest melting point temperature? (A) Iodine, I 2 (B) Mercury, Hg (C) Silicon dioxide, SiO 2 (D) Tetraphosphorous decoxide, P 4O 10 enzyme nucleotide 5. The figure above shows the side of an enzyme (shown in solid and dashed lines) with specific amino acids bound to a nucleotide. What is the interaction that shows how the nucleotide and enzyme bind shown at the indicated arrow? (A) Hydrogen bonding (B) Hydrophillic interactions (C) Hydrophobic interactions (D) Ion-dipole interaction
6. A typical phase diagram for a substance is given below. At what point on the diagram do gas and liquid exist at equilibrium? Pressure (A) A (B) B (C) C (D) D Temperature 7. A 50 ml sample of an unknown liquid is placed in an evacuated closed container and allowed to reach equilibrium. Which of the following increases the vapor pressure of the liquid in the container? (A) Increase the temperature of the sample. (B) Add more of the liquid to the container. (C) Transfer the liquid to a container with twice the volume. (D) Pump an inert gas into the container. 8. Which of the following properties is expected to be lower for hydrazine (N 2H 4) than for nitrogen tetroxide (N 2O 4)? (A) Enthalpy of Vaporization ( H vap) (B) Normal Boiling Point (C) Vapor Pressure (D) All of these are expected to be higher for hydrazine 9. A 0.50 mol sample of F 2 (g) is introduced into an evacuated container. In a two-stepped process, the Kelvin temperature of the sample is tripled, and then the volume is halved. Which of the following one-step changes to the original sample would result in the same final pressure as the two-stepped process? (A) Add 1.5 mol F 2 (g) (B) Add 2.0 mol F 2 (g) (C) Add 2.5 mol F 2 (g) (D) Add 3.0 mol F 2 (g) 10. What is the ratio of the root mean square speed of He (g) at 100 C to that of He (g) at 50 C? (A) (B) (C) (D) 2 1 2 1 323 373 373 323 11. Equal masses of helium and neon gases are placed in a container at 25 C. Which of the following are true? I. The partial pressures of helium and neon are equal. II. The average kinetic energy of helium and neon are equal. III. The room mean square speed of helium and neon are equal. (A) I only. (B) II only. (C) II and III only. (D) I, II, and III. 12. What is the molar mass of a gas if, at STP, it has a density of 2.86 g/l? (A) 8 g/mol (B) 16 g/mol (C) 32 g/mol (D) 64 g/mol 13. He gas is considered the most ideal of all real gases. Which reason(s) account for this statement? I. He has a filled electron shell. II. He exhibits very weak IMFs. III. He has a very small atomic radius. (A) I only (B) I and II only (C) II and III only (D) I, II and III 14. Compared to pure water, salt water has a higher (A) Boiling point temperature (B) Freezing point temperature (C) Vapor pressure (D) None of these are higher for salt water than for water
15. Green spinach leaves were ground up and mixed with ethyl alcohol. A sample of this mixture was then placed on chromatography paper, which is placed in a test tube with a small amount of ethyl alcohol. The results of the experiment after 20 minutes is shown below. Which of the following might be concluded about the pigment circled that traveled 5.5 cm? (A) It is less soluble in ethyl alcohol and less adsorptive to the chromatography paper than the other pigments. (B) It is less soluble in ethyl alcohol and more adsorptive to the chromatography paper than the other pigments. (C) It is more soluble in ethyl alcohol and less adsorptive to the chromatography paper than the other pigments. (D) It is more soluble in ethyl alcohol and more adsorptive to the chromatography paper than the other pigments.
Part 2 Free Response You should allocate 30 minutes to finish this portion of the test. You may use a scientific calculator. A periodic table and data table will be provided. Respond to each part of the questions completely. Be sure to show your work clearly for questions that involve calculations. (From AP Chemistry 1994 #3) 16. A student collected a sample of hydrogen gas by the displacement of water as shown by the diagram above. The relevant data are given in the following table. (a) Calculate the number of moles of hydrogen gas collected. P H2 = P atm P vap,h2o = 745 mmhg 23.8 mmhg = 721 mmhg 1 atm = 0.949 atm 760 mmhg n H2 = PH2 V (0.949 atm) 90.0 ml 1 L R T = 1000 ml 0.08206 atm L = 0.00349 mol (25 + 273 K) mol K (b) Calculate the number of molecules of water vapor in the sample of gas. n H2O = PH2O V R T = 745 mmhg 1 atm 760 mmhg 90.0 ml 1 L 1000 ml 0.08206 atm L = 0.00361 mol H 2O (25 + 273 K) mol K N H2O = 0.00361 mol H 2O 6.022 10 23 molecules H 2O = 2.17 10 1 mol H 2O 21 molecules H 2O (c) Calculate the ratio of the average speed of the hydrogen molecules to the average speed of the water vapor molecules in the sample. v H2 v H2O = MM H2O MM H2 = 18.016 g/mol 2.016 g/mol = 2.99 1 (d) Which of the two gases, H 2 or H 2O, deviates more from ideal behavior? Explain your answer. H 2O deviates more from ideal behavior because it is larger in size and has stronger IMFs than H 2. H 2O has hydrogen bonding, while H 2 has only weak London dispersion forces.
17. Consider the graph shown for the vapor pressure of diethyl ether ((C 2H 5) 2O), ethanol (C 2H 5OH), and water. (a) For the three liquids: (ii) Rank the three liquids in increasing strength of inter-molecular forces. Diethyl ether < ethanol < water (iii) Explain how the rank in part (i) can be inferred from the vapor pressure of the liquids shown in the graph. Substances with weaker IMFs have higher VP. At a particular temperature (e.g. 20 C), diethyl ether has the highest VP (460 torr) so it has the weakest IMF, while water has the lowest VP (20 torr), so it has the strongest IMF. (iv) Explain how the rank in part (i) can be justified using the inter-molecular forces. Diethyl ether has only dipole-dipole interactions, whereas ethanol and water have hydrogen bonding. Because hydrogen bonding is stronger than dipole-dipole interactions, diethyl ether has the weakest IMF among the three. Because water has the ability to form two hydrogen bonding interactions, its hydrogen bonding is stronger than that of ethanol, which can only form one hydrogen bond. (v) One molecule of ethanol is shown below. Draw another molecule and show the attractive intermolecular forces between them.
(b) 20 ml liquid diethyl ether is placed in a closed container at 20 C. After awhile, some diethyl ether remains. (i) Describe what would be observed with the volume of the liquid diethyl ether over time. The volume of the liquid diethyl ether would decrease as it evaporates. When the pressure reaches the equilibrium vapor pressure, the volume of the liquid diethyl ether would stop changing. (ii) Sketch the graph of the pressure of the container over time. 700 600 500 400 300 200 100 0 Time Pressure (torr) (iii) Write the equilibrium constant expression, K p, for the process observed, and find its value. Use pressure units in atm. (C 2H 5) 2O(l) (C 2H 5) 2O(g) K p = P = 450 torr (C2H 5) 2O 1 atm 760 torr = 0.592 (c) A sample of liquid ethanol is placed in a 5.0 L container at 30 C. After an hour, all of the ethanol has been evaporated. What is the greatest volume of liquid ethanol that could have been placed in a container? The density of liquid ethanol is 0.789 g/ml. Because all of the ethanol has evaporated, the maximum pressure would be P vap = 100 torr 1 atm = 0.132 atm. 760 torr n = P V R T = (0.132 atm)(5.0 L) (0.08206 atm L mol K )(30 + 273 K) = 0.0265 mol C 2H 5OH = 1.54 ml 46.07 g C 2H 5OH 1 mol C 2H 5OH 1 ml 0.789 g C 2H 5OH
South Pasadena AP Chemistry Name 10 States of Matter Period Date UNIT TEST BLUEPRINT Part 1: Multiple Choice Format: 15 questions, four answer choices: (A)-(D) Expected time: 25 minutes Allowed resources: Periodic Table, Equations and Constants. No calculators. Q Lesson Topic Objective 1 8.1 Properties of Solids Describe the physical properties of various types of solids. 2 8.1 Descriptions of Solids Describe how attractive and repulsive forces influence the hardness and brittleness of ionic solids. Describe an interstitial or substitutional allow using a particulate representation. Explain how doping a family 14 element can create a semiconductor. 3 8.1 Types of Solid Classify a solid based on its chemical formula and identify the inter-particle force involved. 4 8.1 IMFs Compare the strength of intermolecular forces between molecular compounds. 5 8.2 Biomolecules Show how intermolecular forces are important in determining the structure of biomolecules. 6 8.2 Phase Diagrams Interpret a phase diagram. 7 8.2 Vapor Pressure Explain how vapor pressure is related to the boiling point. 8 8.2 Properties of Liquids Use physical properties to compare the intermolecular forces of liquids. 9 8.2 Gas Laws Relate how physical properties of a gas sample changes when pressure, temperature, or volume changes. 10 8.2 Temperature Molecular Speed Describe the temperature as the average kinetic energy of a sample. Compare the average speeds of various gases at a given temperature. 11 8.2 Partial Pressures Determine the partial pressure of a gas in a mixture of gases. 12 8.2 Ideal Gas Law Determine the properties of a gas sample using the ideal gas law. 13 8.2 Real Gases Describe when and how an gas deviates from ideal behavior. 14 8.3 Colligative Properties Describe how the physical properties of a solution deviates from those of a pure substance (i.e. boiling point, freezing point, vapor pressure). 15 8.3 Separation Techniques Explain how distillation and chromatography can be used to separate components of a mixture based on physical properties. Part 2: Free Response Format: o 1 long question (5-8 parts) o 1 short question (2-4 parts) Expected time: 30 minutes Allowed resources: Periodic Table, Equations and Constants, and scientific calculators. Topics: Any