| 1. Consider the reaction:2 Na(s) + 2 H2O (l) → 2 NaOH (aq) + H2(g) ΔH = -940kJ What is the ΔH for the reaction when 0.5 mol of sodium reacts with excess water?
a. +940 kJ
b. +235 kJ
c. +470 kJ
d. +1880 kJ
e. 3760 kJ
2. 825 mL of water at 56°C is added to 438 mL of water at 17°C. What is the final temperature of the two mixtures?
a. 22.5°C
b. 28.5°C
c. 36.5°C
d. 42.5°C
e. 47.5°C
3. When 15.0 g of water freezes, 5.0 kJ of heat is removed from the water. How much heat would be required to melt 30.0 g of ice?
a. 2.5 kJ
b. 6.0 kJ
c. 75.0 kJ
d. 5.0 kJ
e. 10.0 kJ
4. Which of the following values for ΔH corresponds to an endothermic reaction?
a. +612 kJ
b. -667 kJ
c. -0.01 kJ
d. 0 kJ
e. -1.12 kJ
5. What volume of 78°C water would have to be added to 350 mL of 44°C water to increase the temperature 18°C?
a. 222.25 mL
b. 393.75 mL
c. 418.50
d. 454.50
e. none of the above
6. 2.41 x 104 J are needed to raise the temperature of 105.0 g of magnesium from 25.00°C to 250.0°C. What is the heat capacity of magnesium?
a. 0.101 J/g·LC
b. 0.920 J/g·°C
c. 1.02 x 10-4 J/g·°C
d. 9.20 x 10-4 J/g·°C
e. 1.02 J/g·°C
7. A block of copper with a mass of 87.7 g is heated to 147°C and then transferred to 165.0 mL of water and allowed to come to a temperature equilibrium. The water is initially at 23°C and contained in a styrofoam cup. The specific heat of copper is 0.385 J/g °C. What will be the final temperature of the water?
a. 28.8°C
b. 30.2°C
c. 39.6°C
d. 41.3°C
e. none of the above
8. In the lab, you mix two solutions (each originally at the same temperature) and the temperature of the resulting solution decreases. Which of the following are true?
a. The chemical reaction is releasing energy.
b. The energy released is equal to sp. ht. x mass x ΔT.
c. The chemical reaction is absorbing energy.
d. The chemical reaction is exothermic.
e. More than one of these is true.
9. Which of the following does not have a standard enthalpy of formation equal to zero at 25°C and 1.0 atm?
a. F2 (g)
b. Al (s)
c. H2O (l)
d. H2 (g)
e. They all have a standard enthalpy of zero
10. How much heat is lost from a 25 g block of copper when it cools by 7.1 ° The specific heat capacity of copper is 0.38 J/°C•g.
a. 4.7 J
b. 9.5 J
c. 1.3 J
d. 11.0 J
e. 67.5 J
11. How much heat is required to raise the temperature of 12.24 L of water from 22.0 °C to 26.3 °C The specific heat capacity of water is 4.18 J /°C•g.
a. 8.6 kJ
b. 8.2 kJ
c. 12000 kJ
d. 2.2 x 102 kJ
e. 36.0 kJ
12. A 34.2 g block of aluminum increases in temperature from 22.3 °C to 27.7 °C when 166 J of heat is added to it . What is the specific heat capacity of aluminum in J /°C•g?
a. 0.26
b. 0.45
c. 0.9
d. 31
e. 0.18
13. A reaction run in a calorimeter containing five hundred mL of water releases 8.62 kJ of heat; during the reaction the temperature of the calorimeter and contents increases by 1.821 ° What is the heat capacity of the calorimeter in kJ/°
a. 2.09
b. 4.7
c. 11.6
d. 9.21
e. 14.8
14. Given that the the enthalpy of formation of Fe2O2 is -824.2 kJ/mol, CO is -110.5 kJ /mol and CO2 is -393.5 kJ, calculate the heat of reaction for the reaction:Fe2O2 + 3 CO → 2 Fe + 3 CO2
a. -24.8 kJ
b. +116.5 kJ
c. -3.4 kJ
d. +67.8 kJ
e. +387.6 kJ
15. Given that the the enthalpy of formation of NaOH is -427 kJ/mol, CO2 is -393.5 kJ/mol, and Na2CO3 is -1131 kJ/mol, calculate the heat of reaction for the reaction:2 NaOH + CO2 → Na2CO3 + H2
a. -2095.5 kJ
b. -89.4 kJ
c. -166.5 kJ
d. +89.4 kJ
e. +2095.5 kJ
16. The white pigment TiO2 is prepared by the hydrolysis of TiCl4 as follows:TiCl4 + 2H2O → TiO2 + 4 HCl If the ΔH of formation for TiO2 is -944.7 kJ and the ΔH of formation for TiCl4 is -763.2 kJ and the ΔH of formation for HCl is -92.3 kJ, how much heat is evolved in the production of 39.95 g of titanium oxide?
a. 16.8 kJ
b. 33.6 kJ
c. 67.2 kJ
d. 34.4 kJ
e. none of the above
17. 2.41 x 102 J are needed to raise the temperature of 105.0 g of magnesium from 25.00°C to 250.0° What is the heat capacity of magnesium?
a. 0.101 J/g•°C
b. 0.920 J/g•°C
c. 1.02 x 10-4 J/g•°C
d. 9.20 x 10-4 J/g•°C
e. 1.02 J/g•ºC
18. Which of the following is an endothermic process?
a. freezing of water
b. vaporization of ethanol
c. oxidation of natural gas (as in a Bunsen burner)
d. burning of gasoline
e. condensation of carbon tetrachloride vapor
19. What is the final temperature of a 40-g sample of ethanol (C2H6) at 25.0°C that absorbs 355 J of heat? The specific heat capacity of ethanol is 2.42 J/(g °C).
a. 46.5°C
b. 59.4°C
c. 28.7°C
d. 25.5°C
e. 21.3°C
20. Water gas, a mixture of H2 and CO, is an important industrial fuel produced by the reaction of steam with red hot carbon:C + H2O → CO + H2 If 12 g of carbon are reacted, how much heat in kJ must be supplied in this reaction? The ΔH of formation for H2O is -242 kJ/mol and the ΔH of formation for CO is -110.5 kJ/mol.
a. 131.3 kJ
b. 352.2 kJ
c. 180.9 kJ
d. 123.7 kJ
e. cannot be determined
21. In the reaction from the above problem:C + H2O → CO + H2 the reaction would be considered which of the following?
a. exothermic
b. endothermic
c. isothermic
d. zero
e. cannot be determined
22. Consider the following processes:2A → 1/2B + C ΔH = +5.0 kJ/mol
3/2B + 4C → 2A + C + 3D ΔH = -15.0 kJ/mol
E + 4A → C ΔH = 10.0 kJ/mol Which of the following is the ΔH for the reaction: C → E + 3D
a. 0 kJ/mol
b. +10 kJ/mol
c. -10 kJ/mol
d. -20 kJ/mol
e. +20 kJ/mol
23. The ΔH for the following reaction is -940 kJ:2Na (s) + 2H2O (l) --> 2NaOH (aq) + H2 (g) What is the ΔH for the reaction when 11.5 g of sodium is reacted according to this equation?
a. 940 kJ
b. 235 kJ
c. 470 kJ
d. 1880 kJ
e. 3760 kJ
24. The dissolution of salt in water (NaCl (s) → Na+ + Cl- has a ΔH = +3.9 kJ. What is the reaction enthalpy for the crytalization of salt?
a. 0 kJ
b. +3.9 kJ
c. -3.9 kJ
d. +2.6 kJ
e. -2.6 kJ
25. What is the standard enthalpy of combustion at 25°C for cyclopropane [C3H6]? The ΔH of formation for cyclopropane is +53.3 kJ/mol, for carbon dioxide it is -393.5kJ/mol and for water vapor it is -242.0 kJ/mol.
a. -2235.5 kJ
b. -965.3 kJ
c. +1206.9 kJ
d. +178.3 kJ
e. +654.8 kJ
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