REVIEW QUESTIONS

Chapter 6

  1. What is the change in internal energy (in J ) of a system that releases 575 J of heat to its surroundings and has 425 cal of work done on it?
  2. If an athlete expends playing tennis, how long would she have to play to work off 1.0 lb of body fat? (One pound of body fat is equivalent to 4100 nutritional Calories)
  3. A 27.7 g sample of ethylene glycol, a car radiator coolant, absorbs 588 J of heat from the car engine. What is the initial temperature of the engine, if its final temperature is ? ( of ethylene glycol )
  4. When 155 mL of water at is mixed with 75.0 mL of water at , what is the final temperature? (Assume specific heat of hot and cold water are the same, and density of water )
  5. A sample of a hydrocarbon is placed in a bomb calorimeter and undergoes combustion. The temperature of the calorimeter rises from to . If the calorimeter has a heat capacity of , what is the heat of combustion ( ) for this hydrocarbon in ?
  6. The heat of sublimation for iodine is , at and 1.00 atm . What is for the sublimation of iodine (shown below) under these conditions?
  1. A bomb calorimeter with heat capacity of was used to study combustion of terbium (Tb) in excess oxygen:
When of terbium was burned, a temperature increase of was observed. What is the for the reaction, in of ?
8. One mole of nitrogen gas confined in a cylinder with a piston is heated from to at 1.00 atm .
a) Calculate the work of expansion in Joules.
b) What would have been the temperature change if the gas had been heated with the same amount of energy in a container of fixed volume. (Assume the specific heat of is )
9. How many kJ of heat is produced when 5.00 g of Al reacts with excess chlorine, as shown below:
  1. Consider the following reaction:
a) How many grams of must react to produce an enthalpy change of 5.00 kJ ?
b) How much heat is transferred when 25.0 g of is produced in this reaction?
11. When 6.50 g of solid NaOH is dissolved in 100.0 g of water in a calorimeter, the temperature rises from to . Calculate the change in enthalpy of solution in of NaOH . Assume specific heat of solution is the same as water.
12. When 1.025 g of naphthalene is burned in a bomb calorimeter, the temperature rises from to . Find for combustion of naphthalene in . Heat capacity of the calorimeter is .
13. When 10.0 g of phosphorus is burned in oxygen gas to form solid , enough heat is generated to raise the temperature of 2960 g of water from to . Calculate the enthalpy of formation of solid under these conditions.
14. Calculate the enthalpy change for the reaction below:
based on the following reactions:
  1. Determine the enthalpy change for the reaction below:
based on the following reactions:
  1. Use enthalpies of formation given to determine the standard enthalpy of reaction for the following:
2 Fe
0 -825.5 -1676
  1. Use the enthalpies of formation and the enthalpy of reaction given below to determine the enthalpy of formation for solid .
  1. The heat of vaporization of a liquid ( ) is the heat required to vaporize 1.00 g of a liquid. In one experiment, 60.0 g of liquid nitrogen (b.p. ) are poured into a Styrofoam cup containing 200. g of water at . Calculate the molar heat of vaporization of liquid nitrogen if the final temperature of the water is .
  2. Ice at is placed in a Styrofoam cup containing 361 g of a soft drink at . Some ice remains after the ice and the soft drink reach an equilibrium temperature of . Determine the mass of the ice that has melted. Assume the specific heat of the drink to be the same as pure water. (It requires 334 J of heat to melt 1 g of ice at )
  3. A quantity of 200 mL of 0.862 M HCl is mixed with 200 mL of in a Styrofoam cup. The initial temperature of both solutions is . Calculate the heat of neutralization in if the final temperature of the solution is . Assume specific heat and density of solution to be the same as water.
  4. Determine the enthalpy change for the reaction below:
based on the following reactions: