PRACTICE TEST
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PRACTICE TEST 1) Thirty feet of water exert a pressure of 1 atm. Calculate the pressure (in kPa) exerted on a diver at a depth of 50.0 feet on a standard day? a) 101.3 kPa b) 270.1 kPa c) 760 kPa d) 168.8 kPa e) none of these 3) A container of gas is cooled while the pressure and volume are required to remain constant. What else must happen? a) gas must be allowed to enter the container b) gas must be allowed to leave the container c) gas need not enter or leave the container d) I’m not sure but can I smash the container after this test? 4) A leak proof air filled balloon is placed in a car at a temperature of 20C. During the day the temperature inside the car decreases to -10C. The volume of the balloon will ____________ while the density of the gas inside the balloon will_____________. a) increase / stay the same b) decrease / stay the same c) increase / increase d) decrease / increase e) decrease / decrease ab) increase / decrease 5) Which has the highest energy particles? a) ice at -10C b) liquid water at 20C c) gaseous water at 110C d) since all are water, all have particles moving at the same energy. 6) A sample of gas initially at 4.0 atm is heated from 200. K to 400. K at constant temperature. The resulting pressure of this sample of gas is ______ atm. a) 4.0 b) 2.0 c) 1.0 d) 8.0 e) 16.0 7) Charles’ Law explains why the volume of a gas ______________________ when _________________________. a) shrinks / heated b) expands / cooled c) expands / heated d) shrinks / cooled e) c&d 8) Boyle’s Law relates what two measurable quantities of a gas? a) VP b) PT c) nP d) TV e) Tn 9) How many moles of gas occupy 0.6082 L at 31C and 367 mmHg? a) 0.0118 b) 0.00850 c) 8.94 d) 0.116 e) none of these 10) What is the molar mass of a gas which has a mass of 3.5 grams and occupies a volume of 1.05 L at STP? a) 82 g/mol b) 2500 g/mol c) 74 g/mol d) 230 g/mol e) none of these 11) Which of the following diffuses the slowest at a given temperature? a) N2 b) H2 c) He d) Ar e) cannot be determined 12) Whose Law helped you answer #11? a) Boyle b) Charles c) Kelvin d) Gay Lussac e) Graham 13) If a piece of metal is cooled to 260K and dropped into a cup of water at room temperature, the metal ___________, while the water ______________. a) loses heat / loses heat b) gains heat / gains heat c) gains heat / loses heat d) loses heat / gains heat 14) During a change of state in which liquid water is being changed into gaseous water at 100C the change in free energy (G) is _____________, while the change in enthalpy (H) is ______________, and the change in entropy (S) is _______________. a) positive / positive / positive b) negative / negative / negative c) zero / zero / zero d) zero / positive / positive e) zero / negative / negative ab) zero / positive / negative 15) A common trend observed in nature is that endothermic processes are accompanied by a ______________, while exothermic processes are accompanied by a________________. a) negative G / positive G b) positive G / negative G c) there is no such trend observed in nature. 19) A solid is dissolved in water. The temperature of the water increases. This process is ______________, while the entropy _______________. a) endothermic / increases b) exothermic / decreases c) endothermic / decreases d) exothermic / increases e) none of these 20) The amount of heat required to raise the temperature of 1 mole of a substance by 1C is called a) specific heat capacity b) heat capacity c) molar heat capacity d) none of these 21) The amount of heat required to raise the temperature of 1 gram of a substance by 1C is called a) specific heat capacity b) heat capacity c) molar heat capacity d) none of these (24-27) A certain endothermic chemical reaction involves the transition from a solid reactant and gaseous reactant to form a solid product. 24) Entropy is a) increasing b) decreasing c) constant d) none of these 25) The change in free energy is a) positive b) negative c) insufficient information is given 26) Which trend in nature is being obeyed? a) entropy b) enthalpy c) both d) neither 27) What could you do to make the reaction spontaneous? a) nothing, it will always be non-spontaneous b) heat it c) cool it d) This reaction has a negative free energy change, and is therefore always spontaneous (28-30) At 298K, a particular process has a G of +50kJ and H of +25kJ. 28) This process can best be described as ___________________ and ___________________. a) exothermic / spontaneous b) endothermic / non-spontaneous c) exothermic / non-spontaneous d) endothermic / spontaneous 29) What must be the sign of S? a) + b) c) not enough information given 30) What is the value of S? a) -0.0838 J/K b) –83.8 J/K c) +83.8 J/K d) +0.0838 J/K e) none of these (31-34) At 298K, yet another process has a H of +50kJ and S of +155J/K. 31) G for this process is a) positive b) negative c) not enough information given 32) At 298K, this process can best be described as ___________________ and ___________________. a) exothermic / spontaneous b) endothermic / non-spontaneous c) exothermic / non-spontaneous d) endothermic / spontaneous 33) This process will be spontaneous at ________temperatures and non-spontaneous at ________temperatures. a) high / low b) low / high c) actually this process would be spontaneous at all temps. d) actually this process would be non-spontaneous at all temps. 34) This process would be spontaneous above ________K. a) 32.2K b) 0.0031K c) 323K e) again, this process is spontaneous at all temeratures d) 245K 40) A particular process has a H < 0 and a S < 0. Is it possible for this process to ever achieve a G = 0? a) yes, but it depends on the temperature b) yes, because such a system would always be at equilibrium regardless of the temperature b) no, because G will always be greater than zero c) no, because G will always be less than zero 42) The standard free energy of formation for any element in its standard state is a) 1 kJ/mol b) 10 kJ/mol c) 100 kJ/mol d) 0 kJ/mol 43) The equation __________________ properly calculates the energy associated with the temperature change of a substance, while the equation ___________________ properly calculates the energy change associated with a particular change of state. a) Q = CmT --- Q = CfusmT b) Q = Hvapm --- Q = CmT c) Q = CmT --- Q = Hfusm 45) The atmospheric pressure on a mountain top is ______________ the pressure at sea level. a) lower than b) higher than c) the same as d) cannot be determined 46) The temperature of a gas is increased from 100K to 300K while the pressure is held constant. How does the volume change? a) it increases by 3 times b) it decreases to 1/3 of the original volume c) it does not change 47) Gay Lussac’s Law states that temperature and pressure are related a) directly b) inversely 50) Which of the following equations properly shows how to determine the pressure of a gas (Pgas) which has been collected over water? a) Pgas = Barometric Pressure + vapor pressure of water at observed temperature b) Pgas = vapor pressure of water at observed temperature - Barometric Pressure c) Pgas = Barometric Pressure / vapor pressure of water at observed temperature d) Pgas = vapor pressure of water at observed temperature + Barometric Pressure e) none of these 52) Water will boil if a) it is heated such that the vapor pressure of the water is less than the atmospheric pressure. b) it is heated such that the vapor pressure of the water is equal to the atmospheric pressure. c) the atmospheric pressure is decreased such that it is the same as the vapor pressure of the water. d) the atmospheric pressure is increased such that it is the greater than the vapor pressure of the water. e) b or c 54) a) b) c) d) e) Which of the following equations is stated properly? Molar Mass = mPT/RV Molar Mass = mVT/PR Molar Mass = mRT/PV Molar Mass = dRT/P c&d 55) How much heat energy would be needed to convert 20.0 g of ice at -20.0C to 20.0 g of liquid water at 20.0 C. Note: Cice = 2.09 J/gK; Hfus = 334 J/g for ice; Cliquid water = 4.18 J/gK a) 1020 J b) 9190 J c) 10020 J d) 91200 J e) 9.18 J 56) The enthalpy of combustion for methane is 890. kJ/mol. How many grams of methane would need to be burned to provide enough energy to perform the process described in #55. (Assume all heat is transferred to the water.) a) 1.65 g b) 0.165 g c) 16.5 g d) 0.0165 g e) none of these 57) A sample of gas is placed in a flexible container at STP. At STP, the gas has a volume of 50.0 L. The gas is transported to a new location where the pressure is 76.5 kPa, and the temperature is 85C. What will be the new volume of the gas? a) 20.6 L b) 0.046 L c) 71.6 L d) 86.8 L e) 752 L For 58-64, use the following choices. Mark all that apply. a) solid b) liquid c) gas 58) lowest density 59) 2 states with the highest density 60) Indefinite shape 61) Incompressible. 62) Definite volume. 63) Highest energy particles. 64) Has particles which are in motion NAME_________________________________ GAS, HEAT, THERMODYNAMICS MONSTER TEST -- FREE RESPONSE SHOW ALL WORK AND CIRCLE YOUR ANSWERS OR SUFFER THE WRATH OF YOUR INSTRUCTOR!!! USE BACKS OF SHEETS AS NECESSARY. Helpful facts: R=0.0821 Latm/molK For water: Hvap=40.1 kJ/mol Hfus=6.02 kJ/mol C = 4.18 J/gK Assume all solutions have a density and specific heat capacity identical to water! 1) When 100.0 mL of 1.50 M copper (II) sulfate and 100.0 mL of 3.00 M potassium hydroxide are mixed in a calorimeter, the temperature of the mixture rises from 20.0C to 29.3C. Write the balanced equation for this reaction. CuSO4 (aq) + 2KOH (aq) K2SO4 (aq) + Cu(OH)2 (s) Use the data above to calculate the enthalpy change for this reaction as performed above (don’t forget to include the appropriate sign to indicate whether it is exothermic or endothermic). Calculate the enthalpy change for this reaction as written in the balanced equation (don’t forget to include the appropriate sign to indicate whether it is exothermic or endothermic). HINT: DON’T TRY USING THE SUMMATION EQUATION FOR THIS!!! 2) Calculate the enthalpy change for the following equation: 2B(s) + 3H2(g) B2H6(g) Use the following information to accomplish this task. Clearly show any rearrangements you must make in these equations and the given enthalpy values in the space below. In other words show your work! 4B(s) + 3O2(g) 2B2O3(s) 2H2(g) + O2(g) 2H2O(l) B2H6(g) + 3O2(g) B2O3(s) + 3H2O(l) H = -2509 kJ H = -572 kJ H = -2148 kJ 3) 10.0 grams of solid potassium chlorate are decomposed to form solid potassium chloride and oxygen gas, and the resulting oxygen gas is collected over water at a temperature of 25.0C and a pressure of at 760.0 mm Hg. The vapor pressure of water at 25.0C is 23.8 torr. Write the balanced equation for this decomposition reaction? 2KClO3 (s) 2KCl (s) + 3O2 (g) Use the reference sheets provided to calculate the free energy change (G) for the written balanced equation. Now calculate the free energy change (G) for the reaction as performed in the description written at the top of the page. Is this process spontaneous? Explain in a phrase (not an essay). What would be the sign on S. Explain in a sentence or two. (No need to do any calculations) Use stoichiometry and the ideal gas law to calculate the volume of oxygen gas which is produced? 4) A new cheeseburger called the “heartstopper” contains 3000. kcal per cheeseburger. How many bottles of water (each of which contains 500. mL of water) could be completely vaporized by the energy present in one cheeseburger? Assume the initial temperature of the water is 25C. HINT: the water must be warmed first and then vaporized. 5) The phase diagram for a pure substance is shown below. Use this diagram and your knowledge about changes of phase to answer the following questions. A) Label the SOLID, LIQUID, and GAS regions on the diagram B) Could the substance be water? ___________________ Explain:____________________________________________________ C) Would the solid melt or sublime at extremely high pressures? _______________ D) Would you expect the surface of the solid to be wet during a phase change at normal atmospheric pressure (1 atm)? ___________________ Explain:___________________________________________________ E) What point represents the highest temperature at which you would expect to be able to liquefy the substance? Also, what is the special name given to this point? ________________________ F) What point represents the existence of all three states of matter in equilibrium with one another? Also, what is the special name given to this point. _________________________ G) What is the name of the change of state which occurs as the substance is cooled directly from point Z to point X? __________________________ H) What is the name of the change of state which occurs as the substance is heated directly from point X to point Z? __________________________ 6) 2 H2S(g) + SO2(g) 3 S(s) + 2 H2O(g) At 298 K, the standard enthalpy change, ∆H°, for the reaction represented above is -145 kilojoules. A) Predict the sign of the standard entropy change, ∆S°, for the reaction. Explain the basis for your prediction. B) At 298 K, the forward reaction (i.e., toward the right) is spontaneous. What change, if any, would occur in the value of ∆G° for this reaction as the temperature is increased? Briefly explain your reasoning. C) The absolute temperature at which equilibrium occurs can be predicted. Determine the temperature at which equilibrium is established. (HINT: you will need the summation equation to help with this one and assume the solid sulfur product is in the rhombic form).) D) Is this reaction spontaneous at temperatures above or below this temperature (from C)? Explain. 7) Carbon dioxide gas can react with hydrogen gas to produce carbon monoxide gas and water vapor. The reaction is not spontaneous at room temperature, but becomes spontaneous at a much higher temperature. What can you conclude about the signs of ∆H and ∆S? Explain.
