Accelerated Chemistry Semester 2 Review Sheet

Transcription

1 Accelerated Chemistry Semester 2 Review Sheet The semester test will be given in two parts. The first part is a performance assessment and will be given the day before the semester test. This will include multiple parts and the questions will focus on interpretation of data, calculations, and short answer explanations for important chemical concepts. The second part given on the semester test day will include approximately 65 multiple choice questions. This part will be given online. No work will need to be shown. You will be given a formula sheet and periodic table to use. I. Unit 6: Thermochemistry a. Kinetic Molecular Theory i. Describe the energy change between system and surroundings by molecular collisions. 1. When 15.0 grams of Methane is burned the temperature of the air increases. Describe why this happens in terms of energy and molecular collisions ii. Describe the transfer of kinetic energy to potential energy by molecular collisions 1. In the above example, describe the energy transfer from potential energy to kinetic energy - iii. Use relationships between pressure, volume, temperature/energy and moles to model changes within a closed system. (ie. Gas laws, gas stoichiometry, and density) 1. Describe the relationships between the following variables a. Pressure and Temperature Explain why. b. Volume and Temperature Explain why c. Pressure and Volume Explain why d. List the values of STP e. Explain how to convert from Celsius to Kelvin f. What is molar volume g. A balloon occupies 10.5 L at 22.0 C and 1.15 atm of pressure. What is the volume at STP? h. A gas in a rigid steel container at 25.0 C exerts a pressure of 125 Kpa of pressure. What is the pressure if the temperature is increased to 150 C.

2 i. What is the pressure of 14.0 grams of Oxygen gas at 25 degrees Celsius in a 3.5 liter container? Report your answer in atm. j. What volume does 33.3 grams of CO 2 occupy at STP? k. Sodium Carbonate decomposes into Sodium Oxide and Carbon Dioxide gas when heated. What is the expected volume of Carbon Dioxide gas at STP when 12.5 grams of Sodium Carbonate decomposes? i. What is the volume of Carbon Dioxide if the temperature was degrees Celsius and the pressure was 775 torr? l. Hydrogen and Iodide gases react to produce Hydrogen Iodide gas. What volume of Hydrogen Iodide would be produced when 5.00 liters reacts with excess iodide gas at 350 degrees Celsius and 1.10 atm of pressure? m. What mass of Butane must be combusted to produce 18.0 liters of CO 2 gas at C and 745 torr?

3 b. Enthalpy i. Compare the energies associated with the reactants and the products for chemical and nuclear processes. 1. Looking at the diagram below describe why the reaction is described as an exothermic process. 2. Name two ways to increase the speed of the reaction below. &. On the graph below draw a catalyzed reaction. ii. Compare and calculate the energy associated with the different states of matter based on the kinetic energy of the state (heating curves/phase diagrams) 1. Label the each of the following on the phase diagram below: a. States of Matter, Triple Point, Critical point. Two specific examples of how to change from a liquid to a gas.

4 2. Draw a heating curve below when 15.0 grams of Ice at -50 degrees Celsius is converted to water vapor at 150 degrees Celsius. On the Y axis plot Temperature on the X axis plot Energy. iii. Describe how the overall energy of the system and surroundings is conserved. (Law of Conservation of Energy) 1. If a system performs 15 J of work on the surrroundings and absorbs 25 joules of heat. What is the overall change in energy of the system? What is the change in energy of the surroundings? a. Explain how this applies to the first law of Thermodynamics iv. Calculate the overall enthalpy change for a system including positive/negative integer meaning. 1. See problems below. v. Use the 2 nd law of Thermodynamics to describe matter 1. In any spontaneous process the entropy of the universe vi. Determine the spontaneity of a chemical process 1. Describe is the following process are spontaneous: a. Ball rolling down a hill b. Freezing of water at 20 degrees Celsius c. Rusting of a nail d. CO 2 and H 2 O combining to form Methane vii. Examples: 1. Describe the meaning of the following signs for G, H, S a. - G + G b. - H + H c. - S + S d. Meaning of G? e. Meaning of H? f. Meaning of S? 2. Predict the sign of H: a. Melting of Ice b. Combustion of Gasoline c. Condensation of Water vapor 3. Predict the sign of S: a. Dissolving of NaCl b. Melting of Ice c. Burning of C 4 H 10

5 4. Under what conditions of enthalpy and entropy is a process typically spontaneous? a. If a spontaneous process produces a decrease in entropy, what drives this process? b. A certain process has a - H and a - S. Under what conditions would this process be spontaneous? 5. On page 975 of your book use table R-11 to calculate the H rxn for the following reactions a. Combustions of methane CH 4 b. Ba(s) + 2HCl (aq) BaCl 2 (aq) + H 2 (g) 6. Calculate the H rxn when 10.0 grams of Magnesium is placed in ml of HCl. The temperature increased from 22.0 C to 29.5 C. Assume the Density of the solution is 1.0 g/ml and the specific heat of water to be 4.18 J/g C. 7. Given the bond enthalpy table below, Calculate the H rxn for the following reactions. H 2 + Cl 2 2HCl Bond H-H H-Cl Cl-Cl Bond Enthalpy 436 KJ/mol 431 KJ/mol 242 KJ/mol 8. Calculate G for a reaction if the H is -125 KJ/mol and the S is -350 J/mol*K at 25 degrees Celsius. Is the reaction spontaneous at this temperature? Why?

6 c. Earth Systems i. Identify overall changes in energy as it relates to the earth s climate over time (natural and man-made over decades, centuries, millennia) 1. Review video II. ii. Determine whether the relationships in energy changes are causal or correlational iii. Use logical arguments to evaluate cost benefits and design solutions related to energy resources UNIT 7: Rates and Equilibrium a. Collision Theory i. Relate the amount of energy and number of collisions to the rate of the reaction ii. Explain the collision theory of chemical process 1. Describe the collision theory 2. Describe at least 3 ways to increase the frequency of collisions 3. When increasing the frequency of collisions what happens to the rate? iii. Determine the rate laws and rate mechanisms (initial methods) iv. Examples 1. The following three-step mechanism is proposed for the reaction. Step I: O3 + NO O + NO3 Step II: O+ O3 2 O2 Step III: NO3 + NO 2 NO2 Write the overall reaction: Identify any intermediates: Identify any catalysts Write the rate expression: If the first step is the rate determining step - write the rate law expression below 2. If the following reaction occurred is a single elementary step write the rate law expression: I (aq) + ClO (aq) OH IO (aq) + Cl (aq) 3. Use the information in the table below to write the rate-law expression for the reaction, and explain or show work how you obtained your answer. O3(g) + NO(g) O2(g) + NO2(g) Experiment Number Initial [O3] (mol L - 1 ) Initial [NO] (mol L -1 ) Initial Rate of Formation of [NO2] (mol L -1 s -1 ) x

7 x x x 4. Given the following data write the rate law expression: 2 NO + Cl 2 NOCl 2 [NO] [Cl 2 ] Rate M/sec b. LeChatelier s Principle i. Describe what happens at the molecular level using Lechatelier s Principle 1. For the reaction between N 2 O 4 (g) 2 NO 2 (g) 1. Describe the direction of shift when: i. N 2 O 4 is removed ii. NO 2 is added iii. Volume is increased on the system iv. Addition of a cayalyst ii. Relate amount of product produced due to stresses applied on the system 1. For the endothermic reaction between N 2 (aq) + 3H 2 (aq) 2NH 3 (aq) 1. Describe the change in concentration of ammonia when the following stresses are applied. i. Addition of Nitrogen Gas ii. Decrease in temperature iii. Increase in pressure iv. removal of hydrogen gas iii. Describe an equilibrium system for a chemical process 1. Define an equilibrium system 2. What is needed to be present for a system to be in equilibrium 3. Write the equilibrium expression for the following reaction 2 A(s) + 3 B (g) - 3 C(l) + 2D(g)

8 4. For the reaction between Nitrogen and Hydrogen to produce Ammonia (NH 3 ), Calculate the equilibrium constant when the concentrations of Ammonia is.250 M and the concentration of Nitrogen and Hydrogen gasses is.100m apiece. Write the expression first. i. What is the meaning of the Keq value? ii. What does the Keq value tell you about the speed at which equilibrium is established? 5. For the following equilibrium CO(g) + 2H 2 (g) CH 3 OH(g), calculate the concentration of Hydrogen gas if the Keq is 10.5 and the concentration of CO is.125 M and the concentration of CH 3 OH is.350 M. iv. Relate favorability to equilibrium constants 1. For the following equilibrium values determine if products or reactants are favored x v. Determine and calculate solubility product constants 1. Define Ksp (solubility product constant) 2. Explain the meaning of the small value of Ksp 3. What types of values would you see for Ksp? Explain. 4. The Ksp for Magnesium Sulfide is 1.6 x what is the concentration of Magnesium ion? 1. What is the effect of adding sodium sulfide to this system? Why 5. The concentration of Chloride ions was measured to be 1.2 x 10-5 mol/l at 500 K for a solution of AgCl.(s) What is the Ksp at this temp.

9 III. UNIT 8: Properties of Water a. Water i. Describe properties of water including autoionization, ph, heat capacity, density and polarity, phase diagrams. 1. Write the equation for the autoionization of water, write the Kw expression, what is the numerical value and explain the meaning of the Kw. 2. Which of the following solutes would dissolve in water? Why? a. NaBr b. NH 3 c. C 3 H 8 d. SCl 2 3. Which of the following solutes would dissolve in Benzene? (C 6 H 6 ) Why? a. KCl b. C 2 H 6 c. CBr 4 4. Which of the following solutes when placed in water are considered electrolytes? Why? Label them as strong or weak electrolytes if they will conduct. a. H 2 SO 4 b. NaOH c. CaI 2 d. C 12 H 22 O 11 e. CH 3 OH f. NH 4 NO 3 5. Calculate the Molarity when 25.0 grams of Sodium Sulfate is placed in enough water to make ml of solution. 6. Describe how to make a 250ml of a.250m solution from solid KCl. a. Describe how you would take the.250 M solution above and make ml of a.100m solution of KCl.

10 7. Describe the procedure to make ml of a 2.00 M HCl solution from a 12.0 M stock solution. ii. Explain the effects of energy transfer as it relates to temperature, air movement and the availability of water iii. Describe the mechanical effects of water on earth s materials. (erosion, expansion, transportation) iv. Describe the chemical effects of water on earth s materials. (solubility, oxidation, colligative properties, viscosity) 1. Describe a unsaturated, saturated and supersaturated solution 2. Use the graph below to describe the level of saturation when grams of KNO 3 is dissolved in 100 ml of water at 60 degrees Celsius. What is the saturation level when the solution is carefully cooled to 20 degrees Celsius? 3. What is a colligative property? List the colligative properties studied in class. 4. What substance below will have the highest boiling point? Why? a..150m NaCl b. H 2 O c..200 M C 12 H 22 O 11 d..100 M AlCl 3 i. Of the above solutions which are electrolytes and why? 5. Which solution has the lowest freezing point? Why? a..100 M KBr b. H 2 O c..250 M C 3 H 7 OH d..100 M MgCl 2

11 6. Calculate the new freezing point of a 1.25 m aqueous solution of Calcium Chloride solution. The Kf is 1.86 C/m. The formula is T f =K f mi 7. Calculate the new boiling point of a 2.50m aqueous solution of glucose. The K b is.56 C/m. The formula is T b =K f mi 8. What is the ph of a 1.0 x 10-3 M HCl solution 9. What is the ph of a 1.0 x 10-3 M KOH solution 10. What is the Hydrogen (H 3 O+) and Hydroxide ion concentration in a solution with a ph of What is the ph of a.0025 M Calcium Hydroxide solution 12. What is the ph of a.025 M solution of Acetic Acid with a Ka of 1.8 x What is the Kb of a.500 M solution of methylamine with a ph of v. Analyze the role of water and its future environmental effects vi. Use titrations to determine the concentration of different analytes dissolved in water. 1. List the strong acids and bases 2. What is the characteristic of strong acids and bases 3. Weak acids and bases dissociate. 4. Definea. Bronsted Acid b. Bronsted Base c. Arrhenius Acid d. Arrhenius Base

12 5. Write the dissociation of HS - forming H 3 O +. Label the acid, base, conjugate acid, and conjugate base. 6. Write the dissociation for HS - forming OH -. Label the acid, base, conjugate acid, and conjugate base. 7. What are the products of any neutralization reaction? & 8. Write the balanced chemical equation for when Calcium Hydroxide is mixed with Nitric Acid. (HNO 3 ) ml of 1.50 M Sulfuric acid reacts with 6.89 ml of sodium hydroxide to produce a color change. What is the molarity of NaOH at the equivalence point a. What indicator range would you choose to perform the above titration? 10. Calculate the molarity of 5.50 ml of KOH necessary to neutralize 7.65 ml of a 1.33M solutions of nitric acid. b. Global Impacts i. Use global climate models to describe changes over time on multiple scales ii. Analyze data to predict the future effect of changes in physical/chemical parameters (temperature, precipitation, sea level, ocean ph) on the atmosphere, geosphere, hydrosphere, and cryosphere and its ability to be reversed iii. Evaluate the data to determine different factors such as bias, sample size, uncertainty, etc and how it relates to validity.