Copyright 2015 Edmentum - All rights reserved. During which of the following phase changes is there a gain in energy? I.

Transcription

1 Study Island Copyright 2015 Edmentum - All rights reserved. Generation Date: 03/16/2015 Generated By: Kristina Brown 1. Examine the phase-change diagram below. During which of the following phase changes is there a gain in energy? I. condensing A. III and IV only B. I and IV only C. I and II only D. I, II, III, and IV II. freezing III. melting IV. vaporizing

2 2. Technology Enhanced Questions are not available in Word format. 3. Particles in a gas are arranged A. somewhat close together, but they are free to flow. B. differently depending on the quantity of the gaseous substance. C. very close together in an ordered, regular pattern. D. very far apart; there is no ordered pattern. 4. Melting occurs when a substance changes from a solid state of matter to a liquid state. Typically, heat must be added to a substance to cause melting to occur. On a molecular level, what does heat do to allow melting to occur? A. B. C. D. Crystalline solids have weak intermolecular forces. Heating strengthens these forces until the substance forms a liquid. All substances are only solid on the outside. Heating disintegrates the external solid and allows the internal liquid to flow through. Heat increases the potential energy of the molecules in a substance so that they can overcome the intermolecular forces between them. Heat causes all of the molecules within a substance to break down into their constituent atomic parts. 5. Adding causes the particles in a solid, liquid, or gas to move farther apart and faster. A. gravity B. heat C. mass D. all of these 6. Density is defined as the amount of matter, or mass, per unit volume. According to this definition, which of the following generally has the greatest density? A. a solid

3 B. a gas C. a liquid D. All of these have the same densities. 7. Which of the following correctly lists the states of matter from the most particle movement to the least particle movement? A. gas, liquid, solid B. solid, liquid, gas C. gas, solid, liquid D. liquid, solid, gas 8. Many properties of gases, such as pressure and volume, and gas laws, such as Boyle's Law and Charles' Law, are based on assumptions of the kinetic molecular theory. Which of the following is a basic assumption of the kinetic molecular theory? A. The volumes of the individual gas particles play a significant role in the properties of gases. Particles in a gas move rapidly and constantly in a random pattern. B. C. Uncontained gases eventually reach a maximum volume and then change the direction of their motion. When gas particles collide, some of the kinetic energy is lost rather than transferred. D. 9. Particles in a liquid are arranged A. very far apart; there is no ordered pattern. B. differently depending on the quantity of the liquid substance. C. very close together in an ordered, regular pattern. D. somewhat close together, but they are free to flow. 10. A phase change is an example of a. A. physical change

4 B. physical property C. chemical property D. chemical change Answers 1. A D 4. C 5. B 6. A 7. A 8. B 9. D 10. A Explanations 1. In order for matter to change phases, there must be an overall loss or gain of heat energy. During the processes of freezing and condensing (i.e., when a liquid becomes a solid or when a gas becomes a liquid), there is a loss of heat energy. During the processes of melting and vaporizing (i.e., when a solid becomes a liquid or when a liquid becomes a gas), there is a gain in heat energy Particles in a solid are arranged very close together in an ordered, regular pattern. Particles in a liquid are arranged somewhat close together, but they are free to flow. Particles in a gas are arranged very far apart; there is no ordered pattern. 4. Heating increases the potential energy of the atoms that make up elements and the molecules or ions that make up compounds. When the potential energy of these particles becomes great enough, solid crystalline structures are able to overcome the intermolecular forces that exist within them. Their rigid structures break down, and their atoms or molecules are free to move past each other. Thus, melting is ultimately the result of a change in the potential energy of the atoms or molecules in a substance.

5 5. Adding heat (increasing the temperature) causes the particles in a solid, liquid, or gas to move farther apart and faster. 6. Since the particles in a solid are arranged closer together than particles in a liquid or a gas, solids generally have the greatest density. 7. Gases exhibit the greatest particle movement. In fact, gas particles move very fast in random directions. Liquid particles are also able to move and flow past one another. However, liquid particles do not move as fast as gas particles. Solid particles move very little. They are only able to vibrate slightly in a fixed position. They cannot move from place to place. 8. The kinetic molecular theory makes the following assumptions: Gases are composed of small particles (atoms or molecules) with insignificant volumes that are located far apart from each other. The particles in a gas are neither attracted nor repelled by one another. Gas particles move rapidly, constantly, and independently from one another in a random pattern. Gas particles move in a straight line until they collide with the walls of their container or another gas molecule. At that point, the gas particles change directions and continue along a different straight-line path. If a gas is contained, the particles fill the container regardless of the shape and/or volume of the container. If the gas is not contained, the particles can diffuse into space without limit. All collisions are perfectly elastic. That is, when one gas particle collides with another gas particle, all of its kinetic energy is transferred, so the total kinetic energy remains constant.

6 9. Particles in a solid are arranged very close together in an ordered, regular pattern. Particles in a liquid are arranged somewhat close together, but they are free to flow. Particles in a gas are arranged very far apart; there is no ordered pattern. 10. A physical property is something that can be observed with the senses. Color, size, shape, temperature, and mass are all examples of physical properties. A chemical property is something that can be observed when a substance undergoes a chemical change. Reactivity and flammability are examples of chemical properties. A phase change is an example of a physical change because the substance remains the same when the change occurs. For example, ice, water, and steam are all different forms of water. The chemical composition of the water remains the same in all three forms. In a chemical change, the substance changes into something new. For example, if vinegar and baking soda are combined, they produce carbon dioxide gas, water, and sodium acetate. The products of the reaction are not the same substances as the reactants.