CHE-109-Fall-2019-Exam-3-W_Key

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CHE 109 Fall 2019 Exam 3 Your Name: Your ID: Question #: 1 For each substance, determine the oxidation number of the Cl. Report each answer as a whole number. Substance Oxidation Number on Cl Cl 2 1 NaClO 4 2 1. 2. ____________________________________________________________________________ Question #: 2 What is the oxidation number of Mn in MnO 4 ? A. +7 B. +6 C. +8 D. +4 ____________________________________________________________________________ Question #: 3 Which one is a redox reaction? A. CH 4 ( g ) + 2O 2 ( g ) CO 2 ( g ) + 2H 2 O( l ) B. Na 2 S( aq ) + Fe(NO 3 ) 2 ( aq ) FeS( s ) +2NaNO 3 ( aq ) C. NH 4 Cl( aq ) + KOH( aq ) H 2 O( l ) + KCl( aq ) + NH 3 ( g ) D. K 2 SO 4 ( aq ) + BaCl 2 ( aq ) BaSO 4 ( s ) + 2KCl( aq ) ____________________________________________________________________________
Question #: 4 For the reaction, Fe( s ) + Cu(NO 3 ) 2 ( aq ) Fe(NO 3 ) 2 ( aq ) + Cu( s ) . A. Cu loses electrons and is oxidized. B. Cu gains electrons and is oxidized. C. Cu loses electrons and is reduced. D. Cu gains electrons and is reduced. ____________________________________________________________________________ Question #: 5 Which element is oxidized in the reaction? Fe 2 O 3 + Al Al 2 O 3 + Fe . A. Fe B. O C. Al ____________________________________________________________________________ Question #: 6 In the reaction, 1 [Fe, C, O] is the oxidizing agent and 2 [Fe, C, O] is the reducing agent. 2Fe 2 O 3 ( s ) + 3C( s ) 4Fe( s ) + 3CO 2 ( g ) 1. 2. ____________________________________________________________________________
Question #: 7 For the redox reaction below: Determine the products, if any, that would be formed including any coefficients needed to balance the reaction. 2AgNO 3 ( aq ) + Cu( s ) . A. CuNO 3 (aq) + Ag(s) B. CuNO 3 (aq) + 2Ag(s) C. Cu(NO 3 ) 2 (aq) + Ag(s) D. Cu(NO 3 ) 2 (aq) + 2Ag(s) E. No reaction ____________________________________________________________________________ Question #: 8 When 0.350 moles of HCl react with excess aluminum, how many moles of hydrogen are produced according to the reaction? 2Al( s ) + 6HCl( aq ) 2AlCl 3 ( aq )+3H 2 ( g ) 1 mol H 2 Report your answer with three significant figures. Do NOT include units in your answer. 1. ____________________________________________________________________________ Question #: 9 How many grams of Li 3 N can be formed from 2.40 moles of Li react with an excess of N 2 ? molar mass of Li 3 N = 34.8 g/mol 6 Li( s ) + N 2 ( g ) 2 Li 3 N( s ) . A. 20.0 g Li3N B. 27.9 g Li3N C. 42.0.1 g Li3N D. 83.6 g Li3N ____________________________________________________________________________
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Question #: 10 Methanol reacts with oxygen according to the reaction: 2CH 3 OH+ 3O 2 2CO 2 + 4H 2 O If 0.5 moles of CH 3 OH react with 0.8 moles of O 2 , what is the limiting reactant? 1 [methanol, oxygen] 1. ____________________________________________________________________________ Question #: 11 How many grams of oxygen (molar mass = 32.0 g/mol) can be obtained from the decomposition of 0.150 moles of potassium chlorate? 2 KClO 3 ( s ) 2 KCl( s ) + 3 O 2 ( g ) A. 7.20 g B. 2.40 g C. 3.40 g D. 14.4 g ____________________________________________________________________________ Question #: 12 For the reaction: NaCl( s ) + AgNO 3 ( aq ) AgCl( s ) + NaNO 3 ( aq ) 16 grams of NaCl is added to 100 mL of a 2.0 M AgNO 3 solution. The AgCl precipitate was collected, dried, and weighed, and found to have a mass of 23 g. Which measurement, if any, is the actual yield? A. 23 g AgCl B. 16 g NaCl C. 100 mL of 2.0 M AgNO 3 D. None of the above, the actual yield must be calculated from the values given. ____________________________________________________________________________
Question #: 13 How much excess reactant remains after 1.50 g of lithium (molar mass = 6.94 g/mol) and 1.50 g of nitrogen (28.0 g/mol) combine to form lithium nitride (molar mass - 34.8 g/mol) according to the following chemical equation? 6Li + N 2 2Li 3 N A. 0.25 g B. 0.50 g C. 0.75 g D. 1.0 g ____________________________________________________________________________ Question #: 14 Ethylene reacts with water according to the following reaction: C 2 H 4 ( g ) + H 2 O( l ) C 2 H 5 OH( l ) If the reaction has a theoretical yield of 57 grams of ethanol, but only 37 grams are produced, what is the percent yield of the reaction? 1 % Report your answer with two significant figures. Do NOT include units or the percent sign in your answer. 1. ____________________________________________________________________________ Question #: 15 For the reaction: BaCl 2 ( aq ) + K 2 SO 4 ( aq ) BaSO 4 ( s ) + 2KCl( aq ) 15 grams of BaCl 2 (208.2 g/mol) were added to 100 mL of a 2.0 M K 2 SO 4 solution. The amount of BaSO 4 (233.4 g/mol) precipitate obtained in this reaction was 12.9 g. If the percent yield is 75%, what is the theoretical yield of BaSO 4 ? A. 47.7 g BaSO 4 B. 17.2 g BaSO 4 C. 22.9 g BaSO 4 D. 2.20 g BaSO 4 ____________________________________________________________________________
Question #: 16 What volume of a 0.300 M KCl solution will completely react with 2.00 L of a 0.200 M Pb(NO 3 ) 2 solution? 2KCl (aq) + Pb(NO 3 ) 2 (aq) PbCl 2 (s) + 2KNO 3 (aq) . A. 2.67 L B. 3.92 L C. 4.51 L D. 5.33 L ____________________________________________________________________________ Question #: 17 What volume of 0.550 M phosphoric acid is needed to react completely with 15.00 mL of 0.217 M KOH? H 3 PO 4 ( aq ) + 3KOH( aq ) K 3 PO 4 ( aq ) + 3H 2 O( l ) . A. 11.7 mL B. 4.69 mL C. 1.97 mL D. 38.1 mL ____________________________________________________________________________ Question #: 18 What does "capacity to do work" refer to? A. Thermal equilibrium B. Energy C. First law of thermodynamics D. System ____________________________________________________________________________ Question #: 19
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According to the law of conservation of energy, energy cannot be created or destroyed. Which statement is consistent with this law? A. Energy is created with friction. B. As the cars of a rollercoaster slow to a stop, some energy is destroyed as the car slows down. C. When energy is transformed from one form into another, a small amount of energy is lost. D. Energy can change form, but energy can never change in total amount. ____________________________________________________________________________ Question #: 20 According to the following diagram of a rollercoaster ride, the point with the least potential energy is 1 , [1, 2, 3, 4, 5] and the point with the greatest potential energy is 2 [1, 2, 3, 4, 5]. 1. 2. ____________________________________________________________________________ Question #: 21
A Hershey's candy bar has 210. Cal (that is 210. kcal). Convert this to kJ. 4.184 J = 1 cal 1 kJ Report your answer with three significant figures. Do NOT include units in your answer. 1. ____________________________________________________________________________ Question #: 22 Select the true statement A. Work is a state function because its value is path dependent. B. Heat is not a state function because its value is path independent. C. Internal energy is a state function because its value is path dependent. D. Volume is a state function because its value is not path dependent. ____________________________________________________________________________ Question #: 23 For a thermodynamic system, Δ E sys = 100 J. It follows that: . A. the system is gaining 100 J and the surrounding are losing 100 J. B. the system is losing 100 J and the surroundings are gaining 100 J. C. both the system and the surroundings are losing 100 J. D. this cannot represent an actual system. ____________________________________________________________________________ Question #: 24
Which signs on q and w represent a system that is doing work on the surroundings and absorbing heat from the surroundings? A. q = +, w = B. q = , w = + C. q = +, w = + D. q = , w = ____________________________________________________________________________ Question #: 25 Calculate the work associated with the expansion of a gas from 152.0L to 189.0L at a constant pressure of 2.0 atm. 1 L ·atm = 101.3 J. A. 7.5×10 3 J B. +7.5×10 3 J C. +74 J D. 74 J ____________________________________________________________________________ Question #: 26 A balloon is compressed from 1.65 L to 0.10 L against an external pressure of 1.25 atm. What is the change in internal energy of the system if there is no heat transfer? 101.3 J = 1.00 L atm A. 196 J B. 1.94 J C. +196 J D. +1.94 J ____________________________________________________________________________ Question #: 27
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What is the definition of specific heat capacity ? A. The amount of heat required to raise one gram of a substance by one degree Celsius. B. The amount of heat given off as one gram of a substance is raised by one degree Celsius. C. The amount of temperature change when one joule of heat is added to an object. D. The thermal energy transfer in a chemical reaction. ____________________________________________________________________________ Question #: 28 A 32.0 g sample of a substance is initially at 24.5 °C. After absorbing 1.35 kJ of heat, the temperature of the substance is 68.2 °C. What is the specific heat capacity of the substance? A. 0.619 J/(g ·°C) B. 1.89 g ·°C/J C. 1.72 J/°C D. 0.965 J/(g ·°C) ____________________________________________________________________________ Question #: 29 What is the final temperature when a 55.0 g sample of water, initially at 18.2°C, absorbs 555 J of heat? The specific heat of water is 4.18 J/g · °C. 1 °C Report your answer with three significant figures. Do NOT include units with your answer. 1. ____________________________________________________________________________ Question #: 30 A sample of methanol ( C s = 2.48 J/g·°C) absorbs 3.72 kJ of energy to raise the temperature from 25.0 °C to 45.0 °C. What is the mass of the sample? A. 21.4 g B. 33.3 g C. 75.0 g D. 60.0 g
DRAFT Do Not Use Until Posted. CHE 109 Fall 2019 Exam 3 - Confidential Your Name: Your ID: attachment_for_pubExamUID_lnxp115742156644922823XX_430.jpg Question #: 1 For each substance, determine the oxidation number of the Cl. Report each answer as a whole number. 1. 0 2. +7|7+|7| Question #: 2 Substance Oxidation Number on Cl Cl 2 1 NaClO 4 2
What is the oxidation number of Mn in MnO 4 ? . A. +7 B. +6 C. +8 D. +4 Question #: 3 Which one is a redox reaction? A. CH 4 ( g ) + 2O 2 ( g ) CO 2 ( g ) + 2H 2 O( l ) B. Na 2 S( aq ) + Fe(NO 3 ) 2 ( aq ) FeS( s ) +2NaNO 3 ( aq ) C. NH 4 Cl( aq ) + KOH( aq ) H 2 O( l ) + KCl( aq ) + NH 3 ( g ) D. K 2 SO 4 ( aq ) + BaCl 2 ( aq ) BaSO 4 ( s ) + 2KCl( aq ) Question #: 4 For the reaction, Fe( s ) + Cu(NO 3 ) 2 ( aq ) Fe(NO 3 ) 2 ( aq ) + Cu( s ) . A. Cu loses electrons and is oxidized. B. Cu gains electrons and is oxidized. C. Cu loses electrons and is reduced. D. Cu gains electrons and is reduced. Question #: 5 Which element is oxidized in the reaction? Fe 2 O 3 + Al Al 2 O 3 + Fe . A. Fe B. O
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C. Al Question #: 6 In the reaction, 1 [Fe, C, O] is the oxidizing agent and 2 [Fe, C, O] is the reducing agent. 2Fe 2 O 3 ( s ) + 3C( s ) 4Fe( s ) + 3CO 2 ( g ) 1. Fe 2. C Question #: 7 For the redox reaction below: Determine the products, if any, that would be formed including any coefficients needed to balance the reaction. 2AgNO 3 ( aq ) + Cu( s ) . A. CuNO 3 (aq) + Ag(s) B. CuNO 3 (aq) + 2Ag(s) C. Cu(NO 3 ) 2 (aq) + Ag(s) D. Cu(NO 3 ) 2 (aq) + 2Ag(s) E. No reaction Question #: 8 When 0.350 moles of HCl react with excess aluminum, how many moles of hydrogen are produced according to the reaction? 2Al( s ) + 6HCl( aq ) 2AlCl 3 ( aq )+3H 2 ( g ) 1 mol H 2 Report your answer with three significant figures. Do NOT include units in your answer. 1. 0.175|.175| Question #: 9
How many grams of Li 3 N can be formed from 2.40 moles of Li react with an excess of N 2 ? molar mass of Li 3 N = 34.8 g/mol 6 Li( s ) + N 2 ( g ) 2 Li 3 N( s ) . A. 20.0 g Li3N B. 27.9 g Li3N C. 42.0.1 g Li3N D. 83.6 g Li3N Question #: 10 Methanol reacts with oxygen according to the reaction: 2CH 3 OH+ 3O 2 2CO 2 + 4H 2 O If 0.5 moles of CH 3 OH react with 0.8 moles of O 2 , what is the limiting reactant? 1 [methanol, oxygen] 1. Methanol|methanol|CH3OH| Question #: 11 How many grams of oxygen (molar mass = 32.0 g/mol) can be obtained from the decomposition of 0.150 moles of potassium chlorate? 2 KClO 3 ( s ) 2 KCl( s ) + 3 O 2 ( g ) . A. 7.20 g B. 2.40 g C. 3.40 g D. 14.4 g
Question #: 12 For the reaction: NaCl( s ) + AgNO 3 ( aq ) AgCl( s ) + NaNO 3 ( aq ) 16 grams of NaCl is added to 100 mL of a 2.0 M AgNO 3 solution. The AgCl precipitate was collected, dried, and weighed, and found to have a mass of 23 g. Which measurement, if any, is the actual yield? A. 23 g AgCl B. 16 g NaCl C. 100 mL of 2.0 M AgNO 3 D. None of the above, the actual yield must be calculated from the values given. Question #: 13 How much excess reactant remains after 1.50 g of lithium (molar mass = 6.94 g/mol) and 1.50 g of nitrogen (28.0 g/mol) combine to form lithium nitride (molar mass - 34.8 g/mol) according to the following chemical equation? 6Li + N 2 2Li 3 N . A. 0.25 g B. 0.50 g C. 0.75 g D. 1.0 g Question #: 14 Ethylene reacts with water according to the following reaction: C 2 H 4 ( g ) + H 2 O( l ) C 2 H 5 OH( l ) If the reaction has a theoretical yield of 57 grams of ethanol, but only 37 grams are produced, what is the percent yield of the reaction? 1 % Report your answer with two significant figures. Do NOT include units or the percent sign in your answer.
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1. 65|64|66| Question #: 15 For the reaction: BaCl 2 ( aq ) + K 2 SO 4 ( aq ) BaSO 4 ( s ) + 2KCl( aq ) 15 grams of BaCl 2 (208.2 g/mol) were added to 100 mL of a 2.0 M K 2 SO 4 solution. The amount of BaSO 4 (233.4 g/mol) precipitate obtained in this reaction was 12.9 g. If the percent yield is 75%, what is the theoretical yield of BaSO 4 ? A. 47.7 g BaSO 4 B. 17.2 g BaSO 4 C. 22.9 g BaSO 4 D. 2.20 g BaSO 4 Question #: 16 What volume of a 0.300 M KCl solution will completely react with 2.00 L of a 0.200 M Pb(NO 3 ) 2 solution? 2KCl (aq) + Pb(NO 3 ) 2 (aq) PbCl 2 (s) + 2KNO 3 (aq) . A. 2.67 L B. 3.92 L C. 4.51 L D. 5.33 L Question #: 17 What volume of 0.550 M phosphoric acid is needed to react completely with 15.00 mL of 0.217 M KOH? H 3 PO 4 ( aq ) + 3KOH( aq ) K 3 PO 4 ( aq ) + 3H 2 O( l )
. A. 11.7 mL B. 4.69 mL C. 1.97 mL D. 38.1 mL Question #: 18 What does "capacity to do work" refer to? A. Thermal equilibrium B. Energy C. First law of thermodynamics D. System Question #: 19 According to the law of conservation of energy, energy cannot be created or destroyed. Which statement is consistent with this law? A. Energy is created with friction. B. As the cars of a rollercoaster slow to a stop, some energy is destroyed as the car slows down. C. When energy is transformed from one form into another, a small amount of energy is lost. D. Energy can change form, but energy can never change in total amount. Question #: 20 According to the following diagram of a rollercoaster ride, the point with the least potential energy is 1 , [1, 2, 3, 4, 5] and the point with the greatest potential energy is 2 [1, 2, 3, 4, 5].
1. 3 2. 1 Question #: 21 A Hershey's candy bar has 210. Cal (that is 210. kcal). Convert this to kJ. 4.184 J = 1 cal 1 kJ Report your answer with three significant figures. Do NOT include units in your answer. 1. 879|878| Question #: 22 Select the true statement A. Work is a state function because its value is path dependent. B. Heat is not a state function because its value is path independent. C. Internal energy is a state function because its value is path dependent. D. Volume is a state function because its value is not path dependent. Question #: 23 For a thermodynamic system, Δ E sys = –100 J. It follows that: .
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A. the system is gaining 100 J and the surrounding are losing 100 J. B. the system is losing 100 J and the surroundings are gaining 100 J. C. both the system and the surroundings are losing 100 J. D. this cannot represent an actual system. Question #: 24 Which signs on q and w represent a system that is doing work on the surroundings and absorbing heat from the surroundings? A. q = +, w = – B. q = –, w = + C. q = +, w = + D. q = –, w = – Question #: 25 Calculate the work associated with the expansion of a gas from 152.0L to 189.0L at a constant pressure of 2.0 atm. 1 L ·atm = 101.3 J. A. 7.5 × 10 3 J B. +7.5 × 10 3 J C. +74 J D. 74 J Question #: 26 A balloon is compressed from 1.65 L to 0.10 L against an external pressure of 1.25 atm. What is the change in internal energy of the system if there is no heat transfer? 101.3 J = 1.00 L•atm A. –196 J B. –1.94 J
C. +196 J D. +1.94 J Question #: 27 What is the definition of specific heat capacity ? A. The amount of heat required to raise one gram of a substance by one degree Celsius. B. The amount of heat given off as one gram of a substance is raised by one degree Celsius. C. The amount of temperature change when one joule of heat is added to an object. D. The thermal energy transfer in a chemical reaction. Question #: 28 A 32.0 g sample of a substance is initially at 24.5 °C. After absorbing 1.35 kJ of heat, the temperature of the substance is 68.2 °C. What is the specific heat capacity of the substance? A. 0.619 J/(g ·°C) B. 1.89 g ·°C/J C. 1.72 J/°C D. 0.965 J/(g ·°C) Question #: 29 What is the final temperature when a 55.0 g sample of water, initially at 18.2°C, absorbs 555 J of heat? The specific heat of water is 4.18 J/g · °C. 1 °C Report your answer with three significant figures. Do NOT include units with your answer. 1. 20.6 Question #: 30 A sample of methanol ( C s = 2.48 J/g·°C) absorbs 3.72 kJ of energy to raise the temperature from 25.0 °C to 45.0 °C. What is the mass of the sample?
. A. 21.4 g B. 33.3 g C. 75.0 g D. 60.0 g
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