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Ch 17 Exam Pre-assessment

Matching

Match each item with the correct statement below.
 a. calorimeter d. enthalpy b. calorie e. specific heat c. joule f. heat capacity

1.

quantity of heat needed to raise the temperature of 1 g of water by 1C

2.

SI unit of energy

3.

quantity of heat needed to change the temperature of 1 g of a substance by 1C

4.

quantity of heat needed to change the temperature of an object by 1C

5.

device used to measure the heat absorbed or released during a chemical or physical process

6.

heat content of a system at constant pressure

Match each item with the correct statement below.
 a. heat of reaction d. heat of fusion b. heat of formation e. heat of solution c. Hess's law of heat summation

7.

the enthalpy change for a chemical reaction exactly as it is written

8.

the enthalpy change caused by dissolving a substance

9.

the energy required to melt a solid at its melting point

10.

the change in enthalpy that accompanies the formation of a compound from its elements

11.

states that if you add two or more thermochemical equations to give a final equation, you can also add the heats of reaction to give the final heat of reaction

Multiple Choice
Identify the choice that best completes the statement or answers the question.

12.

A piece of metal is heated, then submerged in cool water. Which statement below describes what happens?
 a. The temperature of the metal will increase. b. The temperature of the water will increase. c. The temperature of the water will decrease. d. The temperature of the water will increase and the temperature of the metal will decrease.

13.

Which of the following is NOT a form of energy?
 a. light c. heat b. pressure d. electricity

14.

When energy is changed from one form to another, ____.
 a. some of the energy is lost entirely b. all of the energy can be accounted for c. a physical change occurs d. all of the energy is changed to a useful form

15.

When your body breaks down sugar completely, how much heat is released compared to burning the same amount of sugar in a flame?
 a. The body releases more heat. b. The body releases less heat. c. The body releases the same amount of heat. d. The body releases no heat.

16.

The quantity of heat required to change the temperature of 1 g of a substance by 1C is defined as ____.
 a. a joule c. a calorie b. specific heat d. density

17.

A piece of candy has 5 Calories (or 5000 calories). If it could be burned, leaving nothing but carbon dioxide and water, how much heat would it give off?
 a. 500 calories c. 5000 joules b. 5 kilocalories d. Not enough information is given.

18.

How many joules are in 148 calories? (1 cal = 4.18 J)
 a. 6.61 J c. 148 J b. 35.4 J d. 619 J

19.

Which of the following is a valid unit for specific heat?
 a. c. b. cal d. C

20.

When 45 g of an alloy, at 25C, are dropped into 100.0 g of water, the alloy absorbs 956 J of heat. If the final temperature of the alloy is 37C, what is its specific heat?
 a. 0.423 c. 9.88 b. 1.77 d. 48.8

21.

Which of the following has the greatest heat capacity?
 a. 1000 g of water c. 1 g of water b. 1000 g of steel d. 1 g of steel

22.

By what quantity must the heat capacity of an object be divided to obtain the specific heat of that material?
 a. its mass c. its temperature b. its volume d. its energy

23.

Standard conditions of temperature and pressure for a thermochemical equation are ____.
 a. 0C and 101 kPa c. 0C and 0 kPa b. 25C and 101 kPa d. 25C and 22.4 kPa

24.

The heat content of a system is equal to the enthalpy only for a system that is at constant ____.
 a. temperature c. pressure b. volume d. mass

25.

On what principle does calorimetry depend?
 a. Hess's law c. law of enthalpy b. law of conservation of energy d. law of multiple proportions

26.

How can the enthalpy change be determined for a reaction in an aqueous solution?
 a. by knowing the specific heat of the reactants b. by mixing the reactants in a calorimeter and measuring the temperature change c. by knowing the mass of the reactants d. The enthalpy change for this type of reaction cannot be determined.

27.

A chunk of ice whose temperature is –20C is added to an insulated cup filled with water at 0C. What happens in the cup?
 a. The ice melts until it reaches the temperature of the water. b. The water cools until it reaches the temperature of the ice. c. Some of the water freezes, so the chunk of ice gets larger. d. none of the above

28.

Calculate the energy required to produce 7.00 mol ClO on the basis of the following balanced equation.
2Cl(g) + 7O(g) + 130 kcal 2ClO(g)
 a. 7.00 kcal c. 130 kcal b. 65 kcal d. 455 kcal

29.

The amount of heat needed to melt one mole of a solid at a constant temperature is called ____.
 a. molar heat of fusion c. heat of reaction b. molar heat of solidification d. enthalpy

30.

What is the heat of solution?
 a. the amount of heat required to change a solid into a liquid b. the amount of heat absorbed or released when a solid dissolves c. the amount of heat required to change a vapor into a liquid d. the amount of heat released when a vapor changes into a liquid

31.

When 10 g of diethyl ether is converted to vapor at its boiling point, about how much heat is absorbed? (CHO, H = 15.7 kJ/mol, boiling point: 34.6C)
 a. 2 kJ c. 0.2 kJ b. 2 J d. Not enough information is given.

32.

Hess's law ____.
 a. makes it possible to calculate H for complicated chemical reactions b. states that when you reverse a chemical equation, you must change the sign of H c. determines the way a calorimeter works d. describes the vaporization of solids

33.

The amount of heat involved in the synthesis of 1 mole of a compound from its elements, with all substances in their standard states at 25C, is called ____.
 a. enthalpy c. standard heat of formation b. heat of reaction d. heat of solidification

34.

H for the formation of rust (FeO) is –826 kJ/mol. How much energy is involved in the formation of 5 grams of rust?
 a. 25.9 kJ c. 66 kJ b. 25.9 J d. 66 J

35.

Calculate H for the reaction of sulfur dioxide with oxygen.
2SO(g) + O(g) 2SO(g)
(HSO(g) = –296.8 kJ/mol; HSO(g) = –395.7 kJ/mol)
 a. –98.9 kJ c. 197.8 kJ b. –197.8 kJ d. Not enough information is given.