Chemistry Chapter 13 – Flashcards
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What is the key difference between a liquid and a gas?
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intermolecular attractions
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Water could be made to boil at 105° C instead of 100 C by ____.
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Increasing external pressure
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Water changes from liquid to solid at 0ºC and what pressure?
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1 atm
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The particles in a liquid are usually...
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closer together and lower in energy than those in a gas.
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The compressibility of a liquid is generally...
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less than that of a gas.
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What is the boiling point of water at standard pressure?
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100ºC
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A volatile liquid
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b. evaporates readily.
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Why does a liquid's rate of evaporation increase when the liquid is heated?
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a. More molecules have enough energy to overcome the attractive forces holding them in the liquid.
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What causes particles in a liquid to escape into a gas state?
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High kinetic energy
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What happens to the temperature of a liquid as it evaporates?
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It decreases.
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The lower mobility of particles in a liquid compared with those in a gas results in the liquid being...
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less disordered.
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Which states of matter can flow?
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gases and liquids only
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Why would a camper near the top of Mt. Everest find that water boils at less than 100ºC?
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There is less atmospheric pressure than at sea level.
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At a given temperature, different liquids will have different equilibrium vapor pressures because...
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the attractive forces between the particles differ among liquids.
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Molecules at the surface of a liquid can enter the vapor phase only if...
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their energy is high enough to overcome the attractive forces in the liquid.
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What is the pressure when a liquid is boiling at its normal boiling point?
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101.3 kPa
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An increase in the temperature of a contained liquid ____.
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causes the vapor pressure above the liquid to increase
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As the atmospheric pressure on the surface of a liquid decreases, its boiling point
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decreases
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At pressures greater than 760 mm Hg, water will boil at...
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a temperature higher than 100ºC.
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If a liquid is sealed in a container and kept at constant temperature, how does its vapor pressure change over time?
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It increases at first, then remains constant.
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Whenever a liquid changes to a vapor, it...
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absorbs heat energy from its surroundings.
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During boiling, the temperature of a liquid...
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remains constant.
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Pressure has an effect on boiling point because pressure affects...
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the entropy of a gas.
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Compared with the particles in a gas, the particles in a liquid...
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move around less
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Which of the following will evaporate the fastest?
a. All samples will evaporate at the same rate.
b. water at 0 ° C
c. water at 20 ° C
d. water at 40 ° C
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water at 40 C
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Which term best describes the process by which particles escape from the surface of a nonboiling liquid and enter the gas state?
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evaporation
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What happens to the rate of evaporation of a liquid as the liquid is cooled?
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It decreases.
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At which of the following elevations relative to sea level will the boiling point of water be the greatest?
a. 3.1 km
b. 127 m
c. sea level
d. -123 m
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d. -123 m
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Which are the first particles to evaporate from a liquid?
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particles with the highest kinetic energy
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The particles in both gases and liquids
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can change positions with other particles.
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If a solid changes directly to a vapor, its equilibrium vapor pressure...
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is determined by the temperature
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The equilibrium vapor pressure of a liquid is
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the pressure exerted by a vapor in equilibrium with its liquid at a given temperature
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Diethyl ether's boiling point is about 35ºC at 1 atm. At 1.5 atm, what will be ether's approximate boiling point?
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40ºC
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The normal boiling point of chloroform, which has a higher vapor pressure than water at 100 ° C, is ____.
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lower than the normal boiling point of water
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If the temperature of a liquid-vapor system at equilibrium is reduced, the...
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concentration of the vapor will decrease
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When does the concentration of a vapor decrease?
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when the rate of condensation exceeds the rate of evaporation
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Vapor pressure is measured when a liquid and its vapor are...
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in equilibrium.
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When heat is applied to a liquid-vapor system at equilibrium, a new equilibrium state will have
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a higher percentage of vapor
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A liquid-vapor system at equilibrium is kept at constant temperature while the volume of the system is doubled. When equilibrium is restored,...
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the vapor pressure is the same as the original vapor pressure
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The equilibrium vapor pressure of a liquid increases with increasing temperature because...
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the average energy of the particles in the liquid increases.
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If the temperature of a liquid-vapor system at equilibrium increases, the new equilibrium condition will...
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have an increased vapor pressure
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If the rate of evaporation from the surface of a liquid exceeds the rate of condensation,...
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the concentration of the vapor is increasing
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If the temperature of a closed liquid-vapor equilibrium system is raised, its vapor pressure...
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increases
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The equilibrium vapor pressure of a molten ionic compound is likely to be
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lower than that of ether
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In a dynamic equilibrium between the liquid state and the gas state, what is true about the rate of evaporation?
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It is equal to the rate of condensation
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If the temperature and surface area of a liquid remain constant,
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the rate of evaporation remains constant
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If the concentration of vapor above a liquid remains zero, then
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no condensation can occur
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For one mole of any substance at its boiling point, the difference in the total energy (enthalpy) of its vapor and the total energy (enthalpy) of its liquid is its molar...
Think, What is the process of a liquid becoming a vapor?
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enthalpy of vaporization
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If the volume of a liquid-vapor system increases, the immediate effect will be a net
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. increase in evaporation.
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If the equilibrium vapor pressure is falling,
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the temperature of the liquid is decreasing
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If the volume of a liquid-vapor system at equilibrium is reduced,
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a higher percentage of liquid will form
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The equilibrium vapor pressure of water is
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specific for any given temperature.
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Which of the following statements is NOT true about the movement of particles in a gas?
a. The aimless path taken by particles is known as a random walk.
b. Particles fill their containers regardless of the shape or volume of the container.
c. Particles travel in straight-line paths until they collide with other objects.
d. Particles usually travel uninterrupted indefinitely.
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Particles usually travel uninterrupted indefinitely.
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Which of the following statements is part of the kinetic theory?
a. all of the above
b. The particles in a gas move rapidly.
c. The particles in a gas are relatively far apart.
d. The particles of a gas move independently of each other.
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all of the above
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What instrument is normally used to measure atmospheric pressure?
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barometer
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What happens to the range of energies of the particles in matter when the temperature is increased?
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The range of energies becomes broader.
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Particles in a gas are best described as ____.
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small, hard spheres with insignificant volumes
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What is one standard atmosphere of pressure in kilopascals?
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101.3 kPa
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The average kinetic energy of water molecules is greatest in ____.
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steam at 100° C
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How does the atmospheric pressure at altitudes below sea level compare with atmospheric pressure at sea level?
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The atmospheric pressure below sea level is higher.
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What causes gas pressure in a container such as a helium balloon?
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the simultaneous collisions of fast-moving particles in the container
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What can happen when the average energy of a liquid's particles decreases?
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freezing
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With which temperature scale is temperature directly proportional to average kinetic energy?
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Kelvin
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The pressure of a gas in a container is 152 mm Hg. This is equivalent to ____.
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0.2 atm
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When a gas is heated, ____.
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b. some of the absorbed energy is converted to potential energy, and some is converted to kinetic energy Correct
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According to the kinetic theory, collisions between molecules in a gas ____.
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b. are perfectly elastic Correct
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The average kinetic energy of the particles of a substance ____.
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a. is directly proportional to the temperature of the substance Correct
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Standard conditions when working with gases are defined as ____.
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b. 0 ° C and 101.3 kPa Correct
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What is the SI unit of pressure?
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pascal
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Compared with a crystalline solid, the particles in an amorphous solid
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occur in random pattern
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Compared with gases, solids are
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imcompressible
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Compared with the particles in a liquid, the particles in a solid usually are
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closer together
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Crystals are characterized by particular patterns that repeat in how many dimensions?
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d. three dimensions only
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Crystals are classified into how many different crystal systems?
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7
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How do crystal systems differ?
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a. in the angles between faces and the number of edges of equal length
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If the particles in a sample of matter have an orderly arrangement and move only in place, the sample is a
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solid
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Most solids ____.
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a. are dense and difficult to compress
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Particles within a solid
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c. vibrate weakly about fixed positions.
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Solids have a definite volume because
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the particles do not have a tendency to change positions.
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The compressibility of solids is generally
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lower than the compressibility of liquids and gases.
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Water molecules freeze in which definite pattern?
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hexagonal
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What causes the high density of solids?
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The particles are packed closely together.
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What is the pattern of points that describe the arrangement of particles in the entire crystal structure?
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crystal lattice
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What is the smallest portion of a crystal lattice that reveals the three-dimensional pattern?
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unit cell
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What is the total three-dimensional arrangement of particles of a crystal?
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crystal structure
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What is the total three-dimensional array of points that describes the arrangement of the particles of a crystal?
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crystal lattice
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When heated, a pure crystalline solid will
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exhibit a definite melting temperature.
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Which of the following is a crystalline solid?
a. a glass bottle
b. a quartz rock
c. a three-dimensional glass cube
d. a plastic milk container
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b. a quartz rock
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Which of the following is an amorphous solid?
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glass
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Which of the following is NOT a property of covalent network crystals?
a. hardness
b. brittleness
c. high melting point
d. high conductivit
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high conductivity
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Which of the following is not correct about crystalline solids?
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They are geometrically irregular.
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Which substance's solid state consists of covalent molecular crystals?
a. water
b. diamond
c. sodium
d. salt
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a. water
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Consider an iron cube and an aluminum cube. If the two cubes were at the same temperature, how would the average kinetic energy of the particles in iron compare with the average kinetic energy of the particles in aluminum?
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There would be no difference in the average kinetic energies.
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A solid with a low melting point is most likely
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b. covalent.
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During the process of freezing, a liquid
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b. loses potential energy.
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Why doesn't water in lakes and ponds of temperate climates freeze solid during the winter and kill nearly all the living things it contains?
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Ice floats
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When water is warmed from its freezing temperature to its temperature of maximum density, it
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contracts
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What is the freezing point of water at standard pressure?
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0ºC
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Which of the following has a melting point greater than room temperature?
a. oxygen
b. water
c. iron
d. bromine
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bromine
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Which of the following statements about freezing is NOT correct?
Select one:
a. All liquids freeze.
b. Water freezes at 0ºC.
c. Not all liquids freeze.
d. Some liquids freeze at room temperature.
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Not all liquids freeze.
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What is the mass of 1 mL of water at its temperature of maximum density?
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1 g
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Which of the following properties do solids share with liquids?
Select one:
a. fluidity
b. definite shape
c. definite volume
d. slow rate of diffusion
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c. definite volume
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The rate of diffusion in solids is very low because the
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particles are not free to move about.
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The amount of energy needed to melt KCl is that compound's
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enthalpy of fusion.
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A solid forms when the average energy of a substance's particles
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decreases.
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Why is ice less dense than liquid water?
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a. The molecules in liquid water can crowd together more compactly than in ice.
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What is the physical change of a liquid to a solid by the removal of heat?
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freezing/solidification
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The energy level of the particles in a solid is
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d. lower than the energy of the particles in liquids and gases.
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At about what temperature does water reach its maximum density?
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4ºC
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When melting and freezing proceed at the same rate, the system is
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in equilibrium
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Above the critical temperature, a substance
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cannot exist in the liquid state.
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The equilibrium lines on a phase diagram meet at the
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triple point
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A system is in equilibrium when
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opposing physical or chemical changes occur at equal rates.
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What is the critical pressure?
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the lowest pressure under which a substance can exist as a liquid at the critical temperature
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Which of the following elements has the ability to undergo sublimation?
a. iodine
b. carbon
c. oxygen
d. sodium
Check
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a. iodine
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If energy is added to a boiling liquid, what happens to the temperature of the liquid?
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a. It does not change.
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How does the molar heat of fusion of ice compare with the molar heat of fusion of other solids?
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a. It is relatively large.
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The molar heat of fusion for water is 6.008 kJ/mol. How much energy would be required to melt 94.0 g of ice?
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a. 31.3 kJ
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What is the characteristic of water that makes steam useful for household heating systems?
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a. high molar heat of vaporization
