P:Chemistry 3202NL Pulbic ExamsQuestions from public ... · oC to 85.0 oC, what is the specific...

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June 2005 28. Which is a closed system? (A) burning candle (B) halogen lightbulb (C) hot water in a sink (D) ripening banana 29. Which involves the greatest energy change? (A) chemical reaction (B) nuclear reaction (C) phase change (D) physical change 30. When the contents of a cold pack are reacted, a cooling effect is observed. How does the energy of the pack and the energy of the surroundings change to get this cooling effect? 32. Which best describes the reaction below? 33. A 10.0 g sample that is 75.0% C 8 H 18 and 25.0% C 2 H 5 OH is completely combusted. Given the fuel values below, how much energy was released? (A) 34.2 kJ (B) 77.4 kJ (C) 387 kJ (D) 432 kJ 34. The molar enthalpy of combustion for glucose, C 6 H 12 O 6 (s) (molar mass = 180.18 g/mol), is -2808 kJ/mol. What mass of glucose must be burned to release 2430 kJ of energy? (A) 101 g (B) 156 g (C) 321 g (D) 561 g 35. How much energy is required to heat 5.0 g of aluminum from 20.0 O C to 100.0 O C? (A) 13 J (B) 17 J (C) 360 J (D) 450 J

Transcript of P:Chemistry 3202NL Pulbic ExamsQuestions from public ... · oC to 85.0 oC, what is the specific...

Page 1: P:Chemistry 3202NL Pulbic ExamsQuestions from public ... · oC to 85.0 oC, what is the specific heat capacity of the metal? (A) 0.237 J/g @ oC (B) 0.568 J/g @ oC (C) 4.22 J/g @ oC

June 2005

28. Which is a closed system?(A) burning candle(B) halogen lightbulb(C) hot water in a sink(D) ripening banana

29. Which involves the greatest energy change?(A) chemical reaction(B) nuclear reaction(C) phase change(D) physical change

30. When the contents of a cold pack are reacted, a cooling effect is observed. How does theenergy of the pack and the energy of the surroundings change to get this cooling effect?

32. Which best describes the reaction below?

33. A 10.0 g sample that is 75.0% C8H18 and 25.0% C2H5OH is completely combusted. Given thefuel values below, how much energy was released?

(A) 34.2 kJ(B) 77.4 kJ(C) 387 kJ(D) 432 kJ

34. The molar enthalpy of combustion for glucose, C6H12O6(s) (molar mass = 180.18 g/mol), is-2808 kJ/mol. What mass of glucose must be burned to release 2430 kJ of energy?(A) 101 g(B) 156 g(C) 321 g(D) 561 g

35. How much energy is required to heat 5.0 g of aluminum from 20.0 OC to 100.0 OC?

(A) 13 J(B) 17 J(C) 360 J(D) 450 J

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36. The graph below represents the heating curve of a substance that starts as a solid below itsfreezing point. What is the melting point of this substance?

(A) 30 °C(B) 55 °C(C) 105 °C(D) 120 °C

37. Water is heated from ice at 0.0 oC to vapour at 110.0 oC. When does the water experiencethe greatest change in potential energy?(A) at 0.0 oC(B) 0.0 oC to 100.0 oC(C) at 100.0 oC(D) 100.0 oC to 110.0 oC

38. Initially a large candle is lit at one end. A student decides to light the other end so that sheis “burning the candle at both ends.” What has doubled in this system?(A) amount of energy released(B) fuel value of the candle(C) molar enthalpy of combustion(D) temperature of the candle

39. Given the data below, what is the ∆Hrxn for: 4 FeO(s) + O2(g) v 2 Fe2O3(s) ?

(A) -574 kJ(B) -555 kJ(C) 555 kJ(D) 574 kJ

40. A student attempting to determine the molar enthalpy of combustion for ethanol uses analcohol burner to heat a tin can which is half full of water. In calculating the energyabsorbed by the water, the result obtained was lower than the accepted value. Which hadthe least affect on the error?(A) amount of soot on the can(B) amount of water in the can(C) heat absorbed by the can(D) distance between the burner and can

53.(a) A butane torch can be used to determine the heat capacity of antifreeze. Butane, C4H10,has a molar heat of combustion of 802.3 kJ/mol. List the laboratory equipment and the dataneeded to determine the specific heat capacity of antifreeze solution.

(b) Calculate the enthalpy change for the following reaction:

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(c) A 1.50 g sample of granola bar is placed in a bomb calorimeter with a heat capacity of 10.2

kJ/oC. When the bar is completely burned the temperature of the calorimeter and itscontents increased by 3.10 oC. What is the fuel value of the bar?

(d) The reaction below shows the combustion of ethyne.C2H2(g) + 2 O2(g) 6 2 CO2(g) + H2O(l)

(i) Use the bond energies in the table below to calculate the molar heat of reaction forethyne.

(ii) A calorimetry experiment performed by a student determined the molar heat of thisreaction to be -1289 kJ/moL. Give two reasons why there is a difference in the ∆Hvalue obtained from calorimetry and the value obtained from bond energies?

June 2006

29. Which best defines the specific heat capacity of a substance?(A) the energy required to raise the temperature of 1.0 g of a substance 1.0 oC(B) the energy required to raise the temperature of 1.0 g of a substance 100.0 oC(C) the energy required to raise the temperature of 1.0 mol of a substance 1.0 oC(D) the energy required to raise the temperature of 1.0 mol of a substance 100.0 oC

30. If 23.9 g of an unknown metal requires 343 J of energy to change its temperature from 24.5oC to 85.0 oC, what is the specific heat capacity of the metal?(A) 0.237 J/g@ oC(B) 0.568 J/g @ oC(C) 4.22 J/g @ oC(D) 868 J/g @ oC

31. A substance undergoes a change that causes the temperature of its surroundings to increasebut the temperature of the substance remains the same. Which best explains what happensto the substance?(A) kinetic energy decreases(B) melts at its freezing point(C) potential energy decreases(D) vaporizes at its boiling point

32. Which best indicates what happens when CH4(g) burns according to the reaction below?

33. For the reaction below, what is the molar heat of formation of

(A) -571.6 kJ(B) -285.8 kJ(C) +285.8 kJ(D) +571.6 kJ

34. What is the symbol for the enthalpy change that occurs when a substance changes fromsolid to liquid, under standard conditions?(A) Ho

cond

(B) Hofus

(C) Hosoln

(D) Hovap

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35. How much energy is absorbed when 10.0 g of water vaporizes at 100.0 oC?(A) 4.07 kJ(B) 22.6 kJ(C) 40.7 kJ(D) 73.3 kJ

36. Which is the correct order of energy changes from greatest to least?

37. What is the fuel value of a 2.00 g sample of peanut butter that produces 45.24 kJ ofenergy?(A) 0.0442 kJ/g(B) 22.6 kJ/g(C) 43.2 kJ/g(D) 90.5 kJ/g

38. What is the melting point of the substance in the graph below?

(A) 30 oC(B) 60 oC(C) 100 oC(D) 120 oC

39. Using the thermochemical equations given, what is the enthalpy of the reaction below?

(A) -101.7 kJ(B) -72.9 kJ(C) 72.9 kJ(D) 101.7 kJ

40. If the molar heat of formation for CH3OH(l)is -239.2 kJ/mol, what is the molar heat offormation for CO(g)?

(A) -367.9 kJ/mol

(B) -110.5 kJ/mol

(C) 110.5 kJ/mol

(D) 367.9 kJ/mol

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53. (a) In order to determine the molar heat of combustion of candle wax, C25H52(s), water isheated in an aluminum can by a candle. The following results were recorded.

If the heat produced from the candle was absorbed by the water and the aluminum can,what is the molar heat of combustion of the candle wax?

(b) How many moles of methanol must burn to raise the temperature of 100.0 g ofaluminum by 80.0 oC? Assume all heat is absorbed by the aluminum, cAl = 0.900 J/g

oC, andthe molar heat of combustion of methanol, CH3OH(l), is -239 kJ/mol.

(c) A 20.0 g sample of NaCl(s), at 801.0 oC, is heated to 1000.0 oC. Given the informationbelow, calculate the total energy required to heat the sample.

(d) Given the data below, calculate the energy required to break the C-H bond.

June 2007

29. Which piece of equipment should be used to create an isolated system?(A) aluminum can(B) bomb calorimeter(C) stoppered flask(D) test tube

30. For a given substance, which process involves the largest heat change?(A) (g) 6 (l)(B) (g) 6 (s)(C) (l) 6 (g)(D) (l) 6 (s)

31. Which compound is most stable?(A) CS2(g), ∆H

of = 117 kJ/mol

(B) C2H4(g), ∆Hof = 52.4 kJ/mol

(C) C2H6(g), ∆Hof = -84.0 kJ/mol

(D) CO2(g), ∆Hof = -394 kJ/mol

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32. A bathtub and a teacup are both full of water at 20.0 oC. Which best illustrates therelationship between the heat capacity and the specific heat capacity of the water in each?

33. If 9.54 kJ of heat is required to raise the temperature of 225.0 g of a substance from 20.5oC to 45.0 oC, what is the specific heat capacity of the substance?(A) 0.00173 J/g@oC(B) 0.578 J/g@oC(C) 1.04 J/g@oC(D) 1.73 J/g@oC

34. Given the specific heat capacity of H2(g) is 14.3 J/goC, how much energy is absorbed when

2.50 g of H2(g) is heated from 17.0 oC to 23.0 oC?

(A) 2.15 × 102 J(B) 4.30 × 102 J(C) 2.15 × 105 J(D) 4.30 × 105 J

35. How much heat is produced when 5.550 moles of H2(g) is consumed in the reaction below?

(A) 285.8 kJ(B) 571.6 kJ(C) 1586 kJ(D) 3172 kJ

36. Which illustrates the first law of thermodynamics?(A) qsystem = -qsurroundings

(B) qsystem = qsurroundings

(C) ∆Tsystem = ∆Tsurroundings(D) ∆Tsystem = -∆Tsurroundings

37. Which describes the reaction below?

38. Which phase change has occurred for a 5.00 g sample of H2O if it has absorbed 1.67 kJ ofheat?

39. What is true of the enthalpy change for a chemical reaction?(A) always decreases(B) always increases(C) is dependent on the pathway(D) is independent of the pathway

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40. Given the information below, what is the molar enthalpy of combustion for ethanol?

(A) -1236 kJ(B) -358 kJ(C) 358 kJ(D) 1236 kJ

53. (a) 5.50 g of NaOH(s) is dissolved in 175 mL of water in a coffee cup calorimeter. If thetemperature of the water increased by 2.1 oC, calculate the molar heat of solution forNaOH(s).

(b) Calculate the total energy required to heat 225 g of H2O from -25.0oC to 80.0oC. (cice = 2.01J/goC)

(c) Using the data below, calculate ∆H for

(d) Using the data below, calculate the enthalpy change for the following reaction.

June 2008

29. What is the amount of heat released when the temperature of a 5.20 g iron nail changesfrom 22.0 EC to 38.5 oC? (ciron = 0.444 J/g

oC)(A) 22.1 J(B) 38.1 J(C) 50.8 J(D) 88.9 J

30. The specific heat capacity of aluminum metal is 0.890 J/goC. What is the heat capacity of a500.0 g aluminum frying pan?(A) 0.00178 J/oC(B) 0.890 J/oC(C) 445 J/oC(D) 562 J/oC

31. Which device best measures changes in kinetic energy?(A) beaker(B) calorimeter(C) thermometer(D) voltmeter

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32. What happens to the water in a bomb calorimeter when an exothermic reaction occurs?

33. Which enthalpy diagram and ∆H best represent the reaction below?

34. When 1 mol of CH3OH(l) decomposes 129 kJ of heat is absorbed. Which thermochemicalequation represents the decomposition of 2 mol of CH3OH(l)?(A) 2 CH3OH(l) + 129 kJ –> 2 CO(g) + 4 H2(g)(B) 2 CH3OH(l) + 258 kJ –> 2 CO(g) + 4 H2(g)(C) 2 CH3OH(l) –> 2 CO(g) + 4 H2(g) + 129 kJ(D) 2 CH3OH(l) –> 2 CO(g) + 4 H2(g) + 258 kJ

35. If 5.74 kJ of energy is required to melt 50.0 g of sodium metal at its melting point, what isthe molar heat of fusion for sodium metal?(A) 0.378 kJ/mol(B) 2.64 kJ/mol(C) 12.5 kJ/mol(D) 287 kJ/mol

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36. The equation below shows the enthalpy change that occurs when NH4NO3 dissolves inwater. Which describes this process?

37. Which statement describes the energy changes that take place when a solid changes to aliquid at a constant temperature?

38. Which involves the greatest amount of energy?(A) combustion(B) condensation(C) neutralization(D) nuclear fission

39. Which compound is most chemically stable?

40. Using the equations below, what is the enthalpy of formation of H2O2(l)?

(A) -376 kJ/mol(B) -188 kJ/mol(C) 188 kJ/mol(D) 376 kJ/mol

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53.(a) 1125.4 g of water at 10.36 oC is cooled to 0 oC and frozen.i) Calculate how much heat is released in this process.

ii) Calculate the number of moles of ammonia that can undergo a phase change from

liquid to gas, using the energy from the process above.

(b) Using the data determine ∆H for the reaction below.

(c) Use the data below to calculate the fuel value of propane.

June 2009

29. Which describes an open system?(A) matter and heat may be stationary(B) matter and heat may be transferred(C) only heat can flow in and out(D) only matter can flow in and out

30. What is the temperature change for a 15 g piece of iron that absorbs 26.5 J of heat? (cFe =0.444 J/g@EC)(A) 0.25 EC (B) 0.78 EC(C) 1.3 EC(D) 4.0 EC

31. Which refers to the amount of energy required to raise the temperature of 1.0 g of asubstance by 1.0 EC?(A) heat capacity(B) molar enthalpy(C) molar heat(D) specific heat capacity

32. How much heat is absorbed by a bomb calorimeter if it increases in temperature by 23.2 EC? (Ccalorimeter = 17.9 J/EC)(A) 0.772 J(B) 1.30 J(C) 415 J(D) 4.99 × 103 J

33. When a “cold pack” is crushed, NH4NO3(s) dissolves in water inside the package. The packis then used as a cooling source for muscle injuries. Which best explains what happens?(A) The water temperature decreases due to the endothermic process.(B) The water temperature decreases due to the exothermic process.(C) The water temperature increases due to the endothermic process.(D) The water temperature increases due to the exothermic process.

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34. What change is occurring if the temperature of a substance remains constant as energy isadded to it?(A) gas to liquid(B) gas to solid(C) liquid to gas(D) liquid to solid

35. At its boiling point, what mass of methanol, CH3OH (32.05 g/mol), is vaporized by 875 kJ ofheat energy? (∆Hvap(CH3OH) = 35.2 kJ/mol)(A) 0.777 g(B) 1.29 g(C) 24.9 g(D) 797 g

36. Which enthalpy notation represents the energy needed to melt iron?(A) ∆Hcomb

(B) ∆Hfusion

(C) ∆Hsolid

(D) ∆Hvap

37. How many moles of chlorine is required to release 55.8 kJ of heat?H2 + Cl2 2 HCl ∆H = !335 kJ→

(A) 0.167 moles(B) 0.334 moles(C) 3.00 moles(D) 6.00 moles

38. What is true for changes in the kinetic and potential energy for section B-C on the graphbelow?

Kinetic Energy Potential Energy

(A) constant decreases

(B) constant increases

(C) decreases constant

(D) increases constant

39. Given the thermochemical equations below, what is the heat of reaction for the formation ofnitrogen dioxide?

NO(g) + ½ O2(g) NO2(g)→

½ N2(g) + ½ O2(g) NO(g) ∆HE = 91.3 kJ→

½ N2(g) + O2(g) NO2(g) ∆HE = 33.2 kJ→

(A) !124.5 kJ(B) !58.1 kJ(C) +58.1 kJ(D) +124.5 kJ

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40. Using the reactions and data given, what is the bond energy for Cl-Cl?

H2(g) + Cl2(g) 2 HCl(g) + 184.6 kJ→

Bond Bond Energy (kJ/mol)

H-H 436

H-Cl 432

(A) 243 kJ/mol(B) 336 kJ/mol(C) 520 kJ/mol(D) 613 kJ/mol

53.(a) A 100.0 g chocolate bar (C7H8N4O2) is burned in a bomb calorimeter that has a heat capacityof 6.50 kJ/EC. Calculate the molar heat of combustion of the chocolate bar if thetemperature of the calorimeter and its contents increases from 21.90 EC to 27.40 EC.

(b) A mixture of 125.0 g of an unreactive metal and 250.0 g of water has a temperature of 25.0 EC. The mixture is heated to a final temperature of 70.0 EC. Calculate the specificheat capacity of the metal if the mixture absorbs 49.7 kJ of heat.

(c) A 2.50 g sample of water is cooled from 95.0 EC to 0.00 EC and is completely frozen.i) Draw the cooling curve for this process.ii) Calculate the energy released by the water sample.

(d) Calculate the enthalpy change for the reaction below.3 NO2(g) + H2O(l) 2 HNO3(l) + NO(g) →

Substance ∆HfE (kJ/mol)

HNO3(l) !174.1

H2O(l) !285.8

NO(g) 91.3

NO2(g) 33.2