Combustion: Part 1

A student places a small amount of water in a glass dish and then carefully places a small paperclip on the surface of the water. The paperclip floats. What happens if the student adds a drop or two of dish soap to the water? Explain your answer.

-Adding soap makes the paperclip fall through the water to the bottom of the dish. Soap is a surfactant. -Surfactants reduce the surface tension of a liquid. -The surface tension of water is what supported the paper clip.

The forces between water molecules are stronger than the forces between ethanol molecules. Which liquid would probably be most difficult for an insect to walk on? Explain your answer.

-An insect would have an easier time walking on the surface of water than on the surface of ethanol. -Water's stronger intermolecular forces lead to higher surface tension. -Higher surface tension allows water to support the insect.

Use the table to identify the phase and phase changes of the elements under the given conditions. Write the name of the substance, phase, or phase change.When the temperature in a room increases from25°C to 33°C ________, changes from a solidto a liquid. In a lab, methane and nitrogen are cooled from-170°C to -200°C. The methane freezes and the nitrogen ________ . When gold is heated to 2,856°C it changes from a liquid to a _____.

-Gallium -condenses -gas

Imagine the movement of a single gas molecule inside a container. Explain the particle's motions in terms of kinetic-molecular theory.

-Gas particles act like tiny, solid spheres. -Gas particles are in constant, random motion. -Gas particles obey Newton's laws of motion. -Faster particles collide more often and with more force. -Collisions are elastic, there is no energy lost as the particle hits the sides.

An industrial chemist is studying a sample of an unkown metal. Describe two ways he could change the metal physically and two ways he could change the metal chemically to try to identify it.

-Heat the metal until it melts (physical change) -Attempt to react the metal with oxygen (chemical change) -Stretch the metal into a wire (physical change) -Attempt to react the metal with acid (chemical change)

Which statements describe phase changes? Check all that apply. -Particles in a liquid need to move more slowly in order to freeze. -Attractive forces overcome the motion of particles when a solid sublimes. -Attractive forces between the particles in a liquid are broken when a liquid boils. -Particles in gas move fast enough to make more attractive forces when the gas condenses.

-Particles in a liquid need to move more slowly in order to freeze. -Attractive forces between the particles in a liquid are broken when a liquid boils.

Describe two uses of surfactants. At least one must be something that was not described in the passage. For each example, explain how the effects of the surfactant make it useful.

-Surfactants are used to help improve gas exchange in the lungs of premature infants. -Surfactants are used to prevent salad dressings from separating. -Pulmonary surfactants reduce the surface tension of the gas exchange surfaces in the lungs, allowing gases to diffuse more easily. -Surfactants help the water molecules and oil molecules in salad dressings interact and mix.

A chemist is studying the properties of a gas under various conditions. He observes that when the gas is at room temperature and low pressure, it behaves as an ideal gas. When the gas is cooled to 10 kelvin and is placed under high pressure, however, it deviates significantly from an ideal gas. Explain these observations.

-The ideal gas model assumes that gas particles experience no intermolecular attractions. -At low temperature, gas particles move slowly. -At high pressures, gas particles are very close together. -The closeness of the gas particles and their low speed allow intermolecular forces to become important at high pressure and low temperature. -The intermolecular forces cause the gas to deviate from ideal behavior.

Both hydrogen sulfide (H2S) and ammonia (NH3) have strong, unpleasant odors. Which gas has the higher effusion rate? If you opened a container of each gas in a corner of a large room, which odor would you detect first on the other side of the room? Assume the temperature is constant. Explain your answer.

-The molar mass of H2S is greater than the molar mass of NH3, making the velocity and effusion rate of NH3 particles faster. -Effusion rate is inversely proportional to molar mass. -NH3 will have a higher average molecule velocity, so it will diffuse faster and will reach the other side of the room more quickly.

What does the diagram show about phases and the phase of the substance as it is heated? Check all that apply. -The substance is a gas at more than 2,000°C. -The particles are close together but move in different directions between 0°C and 2,200°C. -The attractions between the particles increase in region 2. -The speed of the particles increases in region 5. -The substance does not exist as a solid.

-The particles are close together but move in different directions between 0°C and 2,200°C. -The speed of the particles increases in region 5.

A student checks the air in her bicycle tires early in the morning when it is cool outside. If she measures it again later in the day when it is hotter outside, what will she most likely observe? Explain your answer in terms of kinetic-molecular theory.

-The tire pressure will be higher when the temperature is higher. -Pressure is the result of collisions of gas molecules with the walls of the tire. -Temperature is a measure of the average kinetic energy of the gas molecules. -As temperature increases, gas molecules move more quickly and they collide with the tire walls more frequently and with more force. -Pressure and temperature are directly proportional.

A sample of water is mixed with a surfactant. What will most likely happen to the viscosity of the water? Explain your answer.

-The viscosity of the water will decrease. -Surfactants disrupt intermolecular forces within a liquid. -Viscosity is directly related to intermolecular forces. -If intermolecular forces are decreased, viscosity should also decrease.

The list below includes some of the properties of butane, a common fuel. Identify the chemical properties in the list. Check all of the boxes that apply. -denser than water -burns readily in air -boiling point of -1.1°C -odorless -does not react with water

-burns readily in air -does not react with water

The list below includes some of the properties of ammonia. Identify the physical properties in the list. Check all of the boxes that apply. -gas at room temperature -strong, unpleasant odor -reacts with hydrochloric acid -dissolves easily in water -burns in oxygen

-gas at room temperature -strong, unpleasant odor -dissolves easily in water

Which of the following are examples of plasmas? -ice cubes -tails of comets -a gas fire -the ionosphere -a neon sign -a flashlight

-tails of comets -the ionosphere -a neon sign

Which statement best describes the collisions of gas particles according to the kinetic-molecular theory? -When particles pass close enough to one another, their attractions pull them together, and then they bounce apart with no gain or loss of energy. -As particles travel in straight lines, their paths sometimes meet, and then they bounce apart with no gain or loss of energy. -When particles pass close enough to one another, their attractions pull them together, and then they bounce apart with a loss of energy. -As particles travel in straight lines, their paths sometimes meet, and then they bounce apart with a loss of energy.

As particles travel in straight lines, their paths sometimes meet, and then they bounce apart with no gain or loss of energy.

The arrows in the chart below represent phase transitions. Which arrows represent the phase transitions in which heat energy is gained?

1, 2, and 3

A geochemist examines a piece of metal that he found in the soil. He performs tests to identify the metal from its density, electrical conductivity, and melting point. Which statement best describes his investigation? -He is determining physical properties that are sufficient to identify the metal. -He is determining chemical properties that are sufficient to identify the metal. -He is determining physical properties that are insufficient to identify the metal. -He is determining chemical properties that are insufficient to identify the metal.

He is determining physical properties that are sufficient to identify the metal.

Which energy change occurs during boiling? -Some heat energy of the substance is lost. -Heat energy of the substance remains the same. -Most heat energy of the substance is lost. -Heat energy is absorbed by the substance.

Heat energy is absorbed by the substance.

Which procedure could a student use to examine an intensive property of a rectangular block of wood? -Find the mass. -Record the length. -Measure the volume. -Determine the density.

Determine the density.

Jean has a sample of a liquid. If she changes the liquid's phase by _______ it, the molecules will spread out, allowing the sample to expand and fill a container of any shape or volume.

Evaporating

Which statement describes effusion? -It occurs when a gas passes through a tiny hole. -It occurs when a liquid passes through a tiny hole. -It occurs when gas molecules disperse throughout a container. -It occurs when a liquid disperses throughout a container.

It occurs when a gas passes through a tiny hole.

Why are liquids well suited for hydraulics? -Liquids have low densities. -Liquids are incompressible. -Liquids change volume easily. -Liquids have few molecules.

Liquids are incompressible.

Particles in a plasma experience______ collisions than particles in a solid. Based on their state of matter alone, is it easier to speak of the shape of the Sun or the Moon?_______ Two unknown substances are in identical beakers. One is a solid and the other is a plasma. If you were given a scale to allow you to obtain the mass of the substance, and had to guess based on mass alone, you would say that the plasma is in the ______ beaker.

More Moon Lighter

Temperature depends on the average kinetic energy of the particles in a sample. How does this help explain why a plasma-based light does not have a high temperature? -No particles in the plasma have high kinetic energy. -The fastest particles have the greatest mass. -Most particles in the plasma are heavy, slow, and very low density. -The fastest particles transfer most of their energy through collisions.

Most particles in the plasma are heavy, slow, and very low density.

Which statement describes the appearance of a temperature-vs.-time graph? -A horizontal line shows that the temperature increases at a constant rate over time. -A vertical line shows that the temperature decreases at a constant rate over time. -Horizontal lines where the temperature is constant during phase changes connect upward-sloping lines where the temperature increases. -Horizontal lines where the temperature increases are connected by upward-sloping lines where the temperature is constant for each phase.

Horizontal lines where the temperature is constant during phase changes connect upward-sloping lines where the temperature increases.

What happens when a solid is dissolved into a liquid? -Solid particles float toward the surface layer of liquid particles. -Solid particles sink down toward the bottom layer of liquid particles. -Solid particles become evenly dispersed among liquid particles. -Solid particles become suspended in the middle of liquid particles.

Solid particles become evenly dispersed among liquid particles.

Substance X has a fixed volume, and the attraction between its particles is strong. Substance Y has widely spread out particles and can be compressed. What can most likely be concluded about these substances? -Substance X is a crystal, and substance Y is a liquid. -Substance X is a gas, and substance Y is a plasma. -Substance X is a plasma, and substance Y is a crystal. -Substance X is a solid, and substance Y is a plasma.

Substance X is a solid, and substance Y is a plasma.

Which best explains why a crystal is incompressible? -Its molecules remain in position without vibrating. -The molecules of a crystal behave like those of a gas. -There is little, if any, space left between its adjacent molecules. -Its molecules switch positions when they are compressed.

There is little, if any, space left between its adjacent molecules.

The particles in water have less mobility than the particles in oxygen. Which statement best explains this observation? -Water is always colder than oxygen. -Water has a lower density than oxygen. -Water particles have a greater kinetic energy. -Water particles have strong intermolecular forces.

Water particles have strong intermolecular forces.

Keisha makes a table to compare plasmas and solids. Which labels belong in the cells marked X and Y? -X: HighY: High -X: HighY: Low -X: LowY: High -X: LowY: Low

X: HighY: High

Carla makes a small cardboard boat and floats it in a tub of water. When she adds a drop of dish soap behind the boat, the boat moves forward. Which statement best explains what happened? -The soap increased the viscosity of the water behind the boat, allowing the water in front of the boat to flow more easily. -The soap reduced the surface tension behind the boat, causing both water molecules and the boat to be pulled forward. -The soap increased the kinetic energy of the water molecules behind the boat, causing both the molecules and the boat to move forward. -The soap formed an immiscible layer on the water, causing the soap to spread out and push the boat forward.

The soap reduced the surface tension behind the boat, causing both water molecules and the boat to be pulled forward.

Which statement describes how phase changes can be diagrammed as a substance is heated? -The phase is on the y-axis and the temperature is on the x-axis. -The temperature is on the y-axis and the phase is on the x-axis. -The time is on the y-axis and the temperature is on the x-axis. -The temperature is on the y-axis and the time is on the x-axis.

The temperature is on the y-axis and the time is on the x-axis.

Use the information in the table to describe the temperature-vs.-time diagrams. The diagram for gallium will have flat, horizontal lines _____°C. The diagram for methane will have a________line representing the ___________between -183°C and -162°C. For gold, the boiling point corresponds to the y-value at _______°C of the_________line.the middle of the diagonal line. For nitrogen, the line at -210°C will be ________, which represents the_______

at 30 and 2,204 diagonal liquid phase 2,856 top horizontal line flat the change from a solid to liquid

Which is an example of plasmas in nature? -solar cells -plasma balls -auroras -clouds

auroras

Which process most likely takes place when the kinetic energy of molecules overcomes the intermolecular forces? -boiling -condensation -freezing -solidification

boiling

Which list includes only physical properties? -density, reactivity, and conductivity -boiling point, conductivity, and color -color, odor, and flammability -flammability, reactivity, and ductility

boiling point, conductivity, and color

Which sequence represents the relationship between temperature and volume as explained by the kinetic-molecular theory? -higher temperature more kinetic energy more space between particles higher volume -higher temperature less kinetic energy less space between particles higher volume -higher temperature more kinetic energy less space between particles lower volume -higher temperature less kinetic energy more space between particles lower volume

higher temperature more kinetic energy more space between particles higher volume

Which of these is an example of a physical change? -sugar dissolving in warm water -iron rusting in the presence of moist air -wood burning in the presence of oxygen -baking soda reacting with acid to form a gas

sugar dissolving in warm water

What is produced on the top of a pool of water by the mutual attraction between water molecules? -surfactant -surface tension -a much smaller volume -a much higher density

surface tension

Which of these is an example of investigating an intensive property? -weighing sand in a bag -measuring the length of wire -determining if a rock is magnetic -recording the volume of water in a cylinder

determining if a rock is magnetic

Which example involves a phase change in which heat energy is released by the substance? -freezing ice cream -cooking a pot of soup -melting ice under sunlight -watching frost disappear into air

freezing ice cream

If gas particles start colliding with the walls of their metallic container with increased force, what is their direct effect? -lower gas pressure -higher gas pressure -lower volume of gas -higher volume of gas

higher gas pressure

According to the kinetic-molecular theory, the collision between two ideal gas particles is a result of -neither attraction nor repulsion. -repulsion from the wall of the container. -repulsion from other gas particles. -attraction between the two particles.

neither attraction nor repulsion.

What are thermal plasmas?

plasmas that reach a temperature equal to their surroundings

Which of these is a chemical property of a substance? -texture -ductility -reactivity -conductivity

reactivity

Which molecules would most likely cause a liquid to have the lowest viscosity? -large, polar molecules -small, nonpolar molecules -small, polar molecules -large, nonpolar molecules

small, nonpolar molecules

A solid substance turns directly into a gas. Which term describes this change? -deposition -evaporation -melting -sublimation

sublimation

In which phase transition do molecules move directly from a state involving vibration of particles in a fixed position to a state involving random movement of high-speed particles?--evaporation -sublimation -freezing -deposition

sublimation

Suppose you were given a substance and asked to determine whether or not it was a plasma. Write the characteristics you would look for to identify the substance.

-Particles in plasmas collide more often. -Plasma particles have high kinetic energy (they move quickly). -Plasma particles are far apart. -The ionized particles have no fixed volume

Use kinetic-molecular theory to describe what happens when an ice cube or icicle melts. Include how energy is involved and what happens to the motion of the water molecules

-The particles in a solid move faster as the solid absorbs heat. -The particles in a solid overcome the attractions that hold them together as the solid melts. -The particles slide past one another, but are still close together during the liquid phase.

Energy is released during which phase changes? Check all that apply. -boiling -condensing -depositing -freezing -melting -subliming

-condensing -depositing -freezing

Which best explains the relationship between evaporation and temperature? -A liquid evaporates slower at lower temperatures because the molecules are more spread apart and are not pushed as easily from the liquid's surface. -A liquid evaporates faster at lower temperatures because the attractions are decreased and more particles can escape the surface of the liquid. -A liquid evaporates slower at higher temperatures because the vapor pressure of the liquid is higher, so fewer molecules can escape the surface. -A liquid evaporates faster at higher temperatures because more particles have a higher speed and can overcome attractions in the liquid.

A liquid evaporates faster at higher temperatures because more particles have a higher speed and can overcome attractions in the liquid.

A substance is made up of slow-moving particles that have very little space between them. Based on this information, what can most likely be concluded about this substance? -It is not a gas because its particles do not move continuously. -It is a gas because its particles move continuously in a straight line. -It is not a gas because its particles do not have large spaces between them. -It is a gas because its particles move in many different directions.

It is not a gas because its particles do not have large spaces between them.

What happens when the kinetic energy of molecules increases so much that electrons are released by the atoms, creating a swirling gas of positive ions and negative electrons? -Matter changes to a solid state. -Matter changes to a liquid state. -Matter changes to a plasma state. -Matter changes to a gaseous state.

Matter changes to a plasma state.

How does the motion of particles in the sun's plasma compare to the motion of particles in a solid? -Particles in both the plasma and a solid move around to fill available space. -Particles in the plasma move randomly, but particles in a solid vibrate in one place. -Particles in the plasma have low kinetic energy, but particles in a solid have high kinetic energy. -Particles in both the plasma and a solid are made up of fast-moving electrons and cations.

Particles in the plasma move randomly, but particles in a solid vibrate in one place.

A student investigated some properties of lead and recorded the findings in the table below. Which statement is true with respect to the investigation? -The student investigated only the physical properties of lead. -The student investigated only the chemical properties of lead. -The student investigated more physical properties than chemical properties of lead. -The student investigated more chemical properties than physical properties of lead.

The student investigated more physical properties than chemical properties of lead.

Which statement about gases is true? -They are made up of particles that always move very slowly. -They are made up of particles that travel in a curved path when in motion. -They are made up of hard spheres that vibrate quickly in stationary positions. -They are made up of hard spheres that are in random motion.

They are made up of hard spheres that are in random motion.

Glycerol boils at a higher temperature than water. What does this indicate about the attractive forces of glycerol? -They are nonexistent. -They are the same as those in water. -They are stronger than those in water. -They are weaker than those in water.

They are stronger than those in water.

Which postulate of the kinetic-molecular theory applies to the particles of a liquid? -They do not move freely but vibrate in a stationary position. -They can be compressed, which causes a large change in volume. -They have so much kinetic energy that their intermolecular forces are negligible. -They have enough kinetic energy to easily slide by each other.

They have enough kinetic energy to easily slide by each other.

The closeness of particles of gas and their low speeds allow intermolecular forces to become important at certain pressures and temperatures. Which best describes this statement? -This is a limitation of the kinetic-molecular theory. -This is a postulate of the kinetic-molecular theory. -This describes ideal gas behavior using the kinetic-molecular theory. -This describes ideal gas behavior without the kinetic-molecular theory.

This is a limitation of the kinetic-molecular theory.

A student performs the following experiment. Step 1: She pours a colorless solution into a beaker that contains another colorless liquid. Yellow particles appear in the liquid. Step 2: She lets the yellow particles settle in the beaker and then separates the colorless liquid by decantation.What has most likely occurred in the beaker? -a chemical change in step 1 and a physical change in step 2 -a physical change in step 1 and a chemical change in step 2 -chemical changes in both step 1 and step 2 -physical changes in both step 1 and step 2

a chemical change in step 1 and a physical change in step 2

Which is an example of a chemical change? -water evaporating from a puddle -cloth tearing when pulled -wood forming sawdust when cut -bread baking in an oven

bread baking in an oven

When does carbon dioxide absorb the most heat energy?

during sublimation

Which term refers to a property that depends only on the amount of a substance? -flammability -extensive -intensive -reactivity

extensive

Which two conditions can limit the usefulness of the kinetic-molecular theory in describing gas behavior? -high pressure and low temperatures -high pressure and medium temperatures -low pressure and low temperatures -low pressure and medium temperatures

high pressure and low temperatures

A plasma that has particles that never collide frequently enough to exchange kinetic energy and never reach a temperature equal to the surroundings is categorized as a -thermal plasma. -ionized plasma. -low density plasma. -nonthermal plasma.

nonthermal plasma.

Which term best describes the substances that cause oil and water molecules in salad dressing to interact and mix? -surfactants -miscible liquids -immiscible liquids -compressed molecules

surfactants

Which is an example of a plasma that occurs in nature? -a burning tree -the radiant sun -a melting candle -an electric current

the radiant sun

The pictures to the right show two samples of substance X. Answer the questions below about the intensive and extensive properties of substance X. You may assume that both cubes are solid (that is, not hollow inside). Sample A melts at________sample B. Sample B has the same mass as________sample A. Sample A has the same volume asa larger volume than_____sample B. If sample A floats in water, sample B______________ If sample B is attracted to a magnet, sample A_____________

the same temperature as a larger mass than a smaller volume than will also float in water will also be attracted to a magnet

A graph of gas pressure versus the number of particles in a container is a straight line. Which other relationship will have a similar graph? -volume versus pressure, because they are also directly proportional -volume versus temperature, because they are also directly proportional -volume versus pressure, because they are also inversely proportional -volume versus temperature, because they are also inversely proportional

volume versus temperature, because they are also directly proportional

Explain why a fluorescent light bulb is not as hot as an incandescent light bulb.

-Particles in plasmas collide more often, but that does not necessarily give them higher temperature. -Plasma particles have high kinetic energy (they move quickly). -Plasma particles are far apart. -The plasma in a fluorescent bulb has a low density.