Practice Exercises

Record your answers on a separate sheet of paper.

1. A synthesis reaction will occur spontaneously after the activation energy is provided if the heat of formation of the product is

   1. large and negative
   2. small and negative
   3. large and positive
   4. small and positive

2. The reaction of aluminum with dilute H₂SO₄ can be classified as

   1. synthesis
   2. decomposition
   3. single replacement
   4. double replacement

3. For a metal atom to replace another kind of metallic ion in a solution, the metal atom must be

   1. a good oxidizing agent
   2. higher in the activity series than the metal in solution
   3. lower in the electromotive chart than the metal in solution
   4. equal in activity to the metal in solution

4. One reason for a double displacement reaction to go to completion is that

   1. a product is soluble
   2. a product is given off as a gas
   3. the products can react with each other
   4. the products are miscible

5. An endothermic reaction

   1. has a ∆H value that’s negative and would feel cold if it occurred in your hand
   2. has a ∆H value that’s positive and would feel cold if it occurred in your hand
   3. has a ∆H value that’s negative and would feel warm if it occurred in your hand
   4. has a ∆H value that’s positive and would feel warm if it occurred in your hand

6. The heat flowing into 50.0 g of water to produce a 10.0°C rise would be

   1. 5.00 calories
   2. 10.0 calories
   3. 50.0 calories
   4. 500. calories

7. During a phase change, the temperature of a substance

   1. increases
   2. decreases
   3. stays the same
   4. goes down and then up

8. Given the following reaction,

   

   if 64.0 grams of oxygen were to react with an excess of hydrogen,

   1. 968 kJ of energy would be released
   2. 968 kJ of energy would be absorbed
   3. 484 kJ of energy would be released
   4. 484 kJ of energy would be absorbed

9. Given the following reaction,

   

   the decomposition of 1.0 mole of gaseous CO₂ into the elements that compose it would

   1. release 393.5 kJ but would likely not occur
   2. absorb 393.5 kJ but would likely not occur
   3. release 393.5 kJ and would likely occur
   4. absorb 393.5 kJ and would likely occur

10. A ∆H_reaction of –100 kJ/mole indicates the reaction is

    1. endothermic
    2. unstable
    3. in need of a catalyst
    4. exothermic

11. Directions: Before attempting to answer the following questions (11–15), you may want to review the directions for this type of question, found on pages xv–xvi.

    Every question below contains two statements, I in the left-hand column and II in the right-hand column. For each question, decide if statement I is true or false and whether statement II is true or false, and fill in the corresponding T or F ovals in the answer spaces. *Fill in oval CE only if statement II is a correct explanation of statement I.

1. Record your answers here:

   

11. I		II
    If the heat of formation of a compound is a large number preceded by a minus sign, the reaction is exothermic	BECAUSE	the First Law of Thermodynamics states that a negative heat of formation is associated with an exothermic reaction.

12. I		II
    The burning of carbon with excess O2 to form CO2 will go to completion	BECAUSE	when a reaction results in the release of a gas that is allowed to escape, the reaction will go to completion.

13. I		II
    The heat of formation of a compound can be calculated by adding two or more thermal reaction equations	BECAUSE	Hess’s Law states that a heat of reaction can be arrived at by the algebraic summation of two or more other thermal reactions.

14. I		II
    Entropy can be described as a measure of disorder of a system	BECAUSE	when high amounts of energy are released from a reaction, the reaction is said to be exothermic.

15. I		II
    The reaction in which HgO is heated to release O2 is called a decomposition	BECAUSE	in a decomposition reaction, the original compound is broken apart into equal numbers of atoms.