ANSWER: B Colligative properties adding salt will lower the melting point. POINTS: 1 / 1

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1 Name: Score: 21 / 21 points (100%) Review Topic 9: Heat Multiple Choice Identify the choice that best completes the statement or answers the question. B 1. C 2. a. c. b. d. Colligative properties adding salt will lower the melting point. a. 80 cal c cal b. 560 cal d cal q = mass x heat of fusion = 15 x 80 = 1200 B 3. The energy required to melt a solid into a liquid is called a. heat of vaporization c. cooling curve b. heat of fusion d. triple point B 4. heat of fusion deals with melting and freezing a. 202 J c. 808 J b. 404 J d J file:///c:/users/joseph%20morris/desktop/sol%20review%20topics/review%20topic%209/review_topic_9_sg.htm 1/7

2 B 5. q = m C p T = (20)(1.01)(20) = 404 a. c. b. d. Negative H means it is exothermic which means the beginning of the curve will be higher than the end of the curve. C 6. At room temperature, chlorine exists as a gas, bromine exists as a liquid, and iodine exists as a solid. The physical states of these elements indicate that melting point a. decreases from top to bottom with group 17 elements b. is independent of periodic position c. increases from top to bottom within group 17 elements d. is constant within group 17 elements This means that chlorine has the lowest melting and boiling points (since it has already melted and evaporated) and iodine has the highest. So, it increases as we go down the periodic table. D 7. The freezing point and the boiling point of water can be altered by a variety of techniques. Which of the following has little or no effect on the boiling point of water? file:///c:/users/joseph%20morris/desktop/sol%20review%20topics/review%20topic%209/review_topic_9_sg.htm 2/7

3 a. Increasing the air pressure above the liquid b. Adding alcohol to the water c. Adding sodium chloride to the water d. Increasing the amount of water a increasing the pressure can force the liquid to stay a liquid b and c both involve colligative properties, adding a solute to water will increase its boiling point d just having more water does not change the boiling point of the water A 8. Between points 2 and 3, energy is being used to a. melt ice c. evaporate water b. heat water d. heat water vapor During this flat line, the ice is melting D 9. The amount of energy needed to raise one gram of a substance one degree Celsius is a characteristic property known as a. heat of formation c. molar heat of fusion b. heat of vaporization d. specific heat capacity This is the definition of specific heat capacity A KJ/mole 23.4 KJ/mole Molar Heat of Vaporization file:///c:/users/joseph%20morris/desktop/sol%20review%20topics/review%20topic%209/review_topic_9_sg.htm 3/7

4 Water and ammonia have different molar heats of vaporization. The best interpretation, at the molecular level, is that water molecules a. have stronger intermolecular attractions b. occupy larger molecular volumes c. set up stronger repulsive nuclear forces d. collide more frequently with each other Stronger intermolecular attractions would hold the molecules together longer and result in more energy to separate them. So water must have strong attractions since it has a higher molar heat of fusion. C 11. The boiling point of ethanol is 78.3 C. The boiling point of ethanol on the Kelvin scale is approximately a. 26 K c. 351 K b. 178 K d. 451 K = D 12. The system that shows a decrease in entropy (disorder) is a. air escaping from a tire c. salt dissolving in water b. snow melting d. water freezing freezing makes the atoms more orderly. The other ones the particles are spreading out more thus increase the disorder. A 13. If the heat of fusion is 32.2 kj/mol, the amount of heat energy required to melt 5.67 grams of FeO is a kj c kj b kj d kj q= moles x heat of fusion = (0.079)x(32.2) = 2.54 change grams to moles > 5.67 x 1 mol/( ) = file:///c:/users/joseph%20morris/desktop/sol%20review%20topics/review%20topic%209/review_topic_9_sg.htm 4/7

5 A 14. This diagram of a chemical reaction shows that the reaction is a. endothermic c. reversible b. exothermic d. at equilibrium Products have more energy than reactants (energy was absorbed) endothermic D 15. The table above lists the melting and boiling points of some metals. Which metal remains liquid over the widest range of temperature? a. Copper c. Lead b. Iron d. Platinum The metal is a liquid in between these points Cu difference of 1512 Fe difference of 1465 Pb difference of 1417 Pt difference of 2761 A 16. The specific heat capacity of a substance is the quantity of heat required to change the temperature of 1 gram of a substance by a. 1 C c. 10 C b. 5 C d. 20 C file:///c:/users/joseph%20morris/desktop/sol%20review%20topics/review%20topic%209/review_topic_9_sg.htm 5/7

6 The definition says its a 1 to 1 ratio between mass and temperature B 17. The average kinetic energy of a sample of water molecules is a. increased as the temperature is decreased b. increased as the temperature is increased c. unaffected by temperature changes d. always equal to zero Temperature is a measure of the kinetic energy of a object. B 18. An experiment yielded the above temperature and time information. What is the freezing point of the material in this experiment if the material is a solid at time zero? a. 25 C c. 25 C b. 0 C d. 50 C It will be where the line flat lines the first time (second time would be boiling point) C 19. When 92.0 g of ethanol (C 2 H 5 OH) are vaporized at its boiling point of 78.3ºC, it requires 78.6 kj of energy. What is the approximate molar heat of vaporization of ethanol in kj/mol? a c b d The told you that you need kj/mol, so divide the kj by moles. (Note: temperature doesn t play a part in molar heat of vaporization because heat file:///c:/users/joseph%20morris/desktop/sol%20review%20topics/review%20topic%209/review_topic_9_sg.htm 6/7

7 equals moles times molar heat of vaporization) So, turn the grams to moles 92.0g x ( )=2 mol 78.6kJ/2mol = 39.3 D 20. Which of these values is most responsible for changing the boiling and freezing points of a solvent? a. Molar mass of the solvent c. Weight of the solute particles b. Electronegativity of the solvent d. Number of solute particles Colligative properties like boiling point elevation and freezing point depression depend on the concentration of the solute in the solvent in molality, so it would be the number of dissolved particles A 21. If 89.6 joules of heat are needed to heat 20.0 grams of iron from 30.0 C to 40.0 C, what is the specific heat of the iron in? a c b d. 896 q=mc p T 89.6=(20)(x)(40 30) 89.6=200x x=89.6/200=0.448 or, they said they wanted the answer in, so if we plug the numbers in their spots = file:///c:/users/joseph%20morris/desktop/sol%20review%20topics/review%20topic%209/review_topic_9_sg.htm 7/7