Unit 3 Test

PrePublic Review #6

Name:________________

1. Which is a measure of average kinetic energy? (A) calorie (B) enthalpy (C) heat (D) temperature 2. A piece of ice was dropped into liquid water to determine the molar heat of fusion of water. The results are given in the graph. What is the best reason for the change after 2 minutes? (A) room was colder than the water; heat entered the container (B) room was colder than the water; heat left the container (C) room was warmer than the water; heat entered the container (D) room was warmer than the water; heat left the container 3. What is the mass of a piece of iron (cFe = 0.444 J/g.oC) which requires 15.0 J of energy to raise its temperature 12.0 oC? (A) 0.355 g (B) 0.555 g (C) 1.80 g (D) 2.82 g 4. Which phase change is endothermic? (A) gas to liquid (B) gas to solid (C) liquid to gas (D) liquid to solid 5. Using the following two reactions: C (s) + O2 (g) → CO2(g)

ΔH = - 394 kJ

CO (g) + ½ O2 (g) → CO2(g)

ΔH = - 283 kJ

what is the ΔH for the reaction (A) - 677 kJ (B) - 111 kJ (C) 111 kJ (D) 677 kJ

C (s) + ½ O2 (g) → CO(g) ?

6. How much energy is required to vaporize completely a 25.0 g sample of acetone, C3H6O, at its boiling point? (ΔHvap = 30.25 kJ/mol) (A) 1.21 kJ (B) 13.0 kJ (C) 58.1 kJ (D) 769 kJ 7. Given the standard heat of formation, ΔHof , for methanol, C2H5OH(l) is - 278 kJ/mol, which reaction illustrates this process? (A) C2H2 (g) + 2 H2O (g) → C2H5OH(l) + 278 kJ (B) C2H2 (g) + 2 H2O (g) + 278 kJ → C2H5OH(l) (C) 2 C(s) + 3 H2(g) + ½ O2(g) → C2H5OH(l) + 278 kJ (D) 2 C(s) + 3 H2(g) + ½ O2(g) + 278 kJ → C2H5OH(l) 8. Why do nuclear reactions involve greater enthalpy changes than chemical reactions? (A) Chemical bonds are stronger than nuclear forces. (B) Chemical bonds are weaker than nuclear forces. (C) Nuclear reactions involve elements with larger atomic numbers. (D) Nuclear reactions involve elements with smaller atomic numbers. 9. What is the fuel value of a 3.00 g sample of banana that produces 12 110 J of energy? (A) 2.48 kJ/g (B) 4.04 kJ/g (C) 16.2 kJ/g (D) 36.3 kJ/g 10. Use the table below to calculate the molar enthalpy of combustion for methane. CH4 (g) + 2 O2 (g) → CO2 (g) + 2 H2O (g) Compound CH4(g) CO2(g) H2O(g)

ΔHof (kJ/mol) - 75 -394 -242

(A) (B) (C) (D)

- 803 kJ/mol - 561 kJ/mol 561 kJ/mol 803 kJ/mol

11. (A) (B) (C) (D)

Which is a closed system? burning candle halogen lightbulb hot water in a sink ripening banana

12. Which enthalpy diagram and corresponding ΔH represents the reaction below? CH4 (g) + 2 O2 (g) → CO2 (g) + 2 H2O (g) + energy

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

14. Which sections of the heating curve below represent a potential energy increase?

(A) (B) (C) (D)

AB and CD AB and DE BC and CD BC and DE

15. 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? Energy of the pack (A) (B) (C) (D)

Energy of the surroundings

decreases decreases increases increases

decreases increases decreases increases

16. Which is true for the energy change of ice when it melts at 0 oC? Kinetic Energy Potential Energy (A) (B) (C) (D)

constant constant increases increases

decreases increases decreases increases

17. Which best describes the reaction below? C(s) + O2(g) → CO2(g) + 393.5 kJ Type of reaction (A) (B) (C) (D)

endothermic endothermic exothermic exothermic

Potential energy of products greater than reactants less than reactants greater than reactants less than reactants

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

(A) (B) (C) (D)

Substance

Fuel Value

C8H18 C2H5OH

47.7 kJ/g 29.66 kJ/g

34.2 kJ 77.4 kJ 387 kJ 432 kJ

19. The molar enthalpy of combustion for glucose, C6H12O6(s), is -2808 kJ/mol. What mass of glucose must be burned to release 2430 kJ of energy? (M = 180.18 g/mol) (A) 101 g (B) 156 g (C) 321 g (D) 561 g 20. How much energy is required to heat 5.0 g of aluminum from 20.0 oC to 100.0 oC? (cAl = 0.900 J/g.oC) (A) 13 J (B) 17 J (C) 360 J (D) 450 J 21. The graph below represents the heating curve of a substance that starts as a solid below its freezing point. What is the melting point of this substance?

(A) (B) (C) (D)

30 °C 55 °C 105 °C 120 °C

22. Water is heated from ice at 0.0 oC to vapour at 110.0 oC . When does the water experience the 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 23. Initially a large candle is lit at one end. A student decides to light the other end so that she is “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 24. Given the data below, what is the ΔHrxn for: 4 FeO(s) + O2(g) → 2 Fe2O3(s) ? Substance FeO(s) Fe2O3(s) (A) (B) (C) (D)

ΔHf (kJ/mol) -268 -823

-574 kJ -555 kJ 555 kJ 574 kJ

25. A student attempting to determine the molar enthalpy of combustion for ethanol uses an alcohol burner to heat a tin can which is half full of water. In calculating the energy absorbed by the water, the result obtained was lower than the accepted value. Which had the 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 26. (A) (B) (C) (D)

Which piece of equipment should be used to create an isolated system? aluminum can bomb calorimeter stoppered flask test tube

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

28. (A) (B) (C) (D)

Which compound is most stable? CS2(g), ΔHof = 117 kJ/mol C2H4(g), ΔHof = 52.4 kJ/mol C2H6(g), ΔHof = -84.0 kJ/mol CO2(g), ΔHof = -394 kJ/mol

29. A bathtub and a teacup are both full of water at 20.0 oC. Which best illustrates the relationship between the heat capacity and the specific heat capacity of the water in each? Heat capacity (A) (B) (C) (D)

H2Obathtub H2Obathtub H2Obathtub H2Obathtub

= = > >

H2Oteacup H2Oteacup H2Oteacup H2Oteacup

Specific Heat Capacity H2Obathtub H2Obathtub H2Obathtub H2Obathtub

= < = <

H2Oteacup H2Oteacup H2Oteacup H2Oteacup

30. If 9.54 kJ of heat is required to raise the temperature of 225.0 g of a substance from 20.5 oC 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 31. Given the specific heat capacity of H2(g) is 14.3 J/g. oC, 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 32. How much heat is produced when 5.550 moles of H2(g) is consumed in the reaction below?

2 H2(g) + O2(g) → 2 H2O(l) + 571.6 kJ (A) (B) (C) (D)

285.8 kJ 571.6 kJ 1586 kJ 3172 kJ

33. Which illustrates the first law of thermodynamics? (A) qsystem = -qsurroundings (B) qsystem = qsurroundings (C) ΔTsystem = -ΔTsurroundings (D) ΔTsystem = ΔTsurroundings

34. Which describes the reaction below?

2 H2(g) + O2(g) → 2 H2O(l) + 571.6 kJ (A) (B) (C) (D)

Type endothermic endothermic exothermic exothermic

ΔH negative positive negative positive

38. Which phase change has occurred for a 5.00 g sample of H2O if it has absorbed 1.67 kJ of heat? (A) H2O(l) → H2O(s) (B) H2O(s) → H2O(l) (C) H2O(g) → H2O(l) (D) H2O(l) → H2O(g) 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 40. Given the information below, what is the molar enthalpy of combustion for ethanol?

C2H5OH(l) + 3 O2(g) → 2 CO2(g) + 3 H2O(g) Species C2H5OH(l) CO2(g) H2O(g) (A) (B) (C) (D)

ΔHof (kJ/mol) -278 -394 -242

-1236 kJ -358 kJ +358 kJ +1236 kJ

Extended Response 41. A 0.910 g sample of sucrose, C12H22O11, (Molar Mass = 342.34 g/mol) is burned in a bomb calorimeter and the temperature of the calorimeter and contents increased from 22.5 oC to 27.5 oC. If the heat capacity of the calorimeter and contents was 4.50 kJ/OC, calculate the molar heat of combustion of sucrose.

42. When a 2.00 g sample of pure phenol, C6H5OH(s), is burned according to the equation below, 65.0 kJ of heat is released. C6H5OH(s) + 7 O2 (g) → 6 CO2 (g) + 3 H2O (l) (i) Calculate the molar heat of combustion for phenol.

(ii) Using the data below, calculate the standard heat of formation, ΔHof, of phenol. Substance C6H5OH(s) CO2 (g) H2O (l)

ΔHof (kJ/mol) ? - 394 - 286

43. Using the bond energies given, determine the enthalpy of reaction for:

2 H2 + O2 → 2 H2O Bond H-H O=O H-O

Bond Energy (kJ) 436 498 464

45. Calculate the enthalpy change for the following reaction: 4 HCl(g) + O2(g) ÷ 2 Cl2(g) + 2 H2O(g) Given the following information: H2(g) + Cl2(g) → 2HCl(g)

ΔH = -185 kJ

H2(g) + ½ O2(g) → H2O(l)

ΔH = -285.8 kJ

H2O(g) → H2O(l)

ΔH = 40.7 kJ

46. 5.50 g of NaOH(s) is dissolved in 175 mL of water in a coffee cup calorimeter. If the temperature of the water increased by 2.1 oC, calculate the molar heat of solution for NaOH(s).

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

48. Using the data below, calculate the enthalpy change for the following reaction. 2 N2(g) + 5 O2(g) → 2 N2O5(g)

ΔH = ?

N2(g) + 3 O2(g) + H2(g) → 2 HNO3(aq)

ΔH = -87.1 kJ

N2O5(g) + H2O(l) → 2 HNO3(aq)

ΔH = -76.6 kJ

½ O2(g) + H2(g) → H2O(aq)

ΔH = -285.8 kJ