Hon Chem: Combustion Part 1 A

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

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

What happens as a result of the kinetic energy of the particles in a liquid being comparable with the intermolecular attractions between the particles? The particles do not move enough to change positions, so the liquid is not compressible. The particles move enough that they separate from one another and take the shape of their container. The particles do not move enough, so they are fixed in place, and the liquid has a fixed volume. The particles move enough that they are not fixed in place, and the liquid can flow.

The particles move enough that they are not fixed in place, and the liquid can flow

Which is an intensive property of a substance? density volume length mass

density

When does carbon dioxide absorb the most heat energy? during freezing during deposition during sublimation during condensation

during sublimation

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

extensive

Which term best describes liquid behavior under pressure? incompressible compressed immiscible surfactant

incompressible

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

Liquids and solids are referred to as "condensed phases" because the attractive forces cause molecules to become stationary. leave little space between the molecules. create large spaces between the molecules. that hold the molecules together are negligible.

leave little space between the molecules

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 molar heat of fusion for water is 6.01 kJ/mol. How much energy must be added to a 75.0-g block of ice at 0°C to change it to 75.0 g of liquid water at 0°C?Use q=nH 1.44 kJ 10.2 kJ 12.5 kJ 25.0 kJ

25.0 kJ

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

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

auroras

Water can dissolve other substances. Which factor best contributes to this property of water? Water is made up of ionic bonds. Water has weak intermolecular forces. Water is denser than most substances. Water particles are not fixed in place.

Water particles are not fixed in place

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

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

Which description best characterizes the motion of particles in a solid? slow but able to move past one another fast and widely spaced not moving vibrating around fixed positions

vibrating around fixed positions

Which of these is an extensive property of a substance? color hardness malleability volume

volume

NaCl has a Hfus = 30.2 kJ/mol. What is the mass of a sample of NaCl that needs 732.6 kJ of heat to melt completely? Use q=nH 24.3 g 82.7 g 1,407.1 g 1,417.7 g

1,417.7 g

Copper has a Hfus = 13.0 kJ/mol. What mass of copper releases 112.4 kJ of heat as it freezes? Use q=nH 9.42 g 6.75 g 549 g 1590 g

549 g

A sample of substance X that has a mass of 326.0 g releases 4325.8 cal when it freezes at its freezing point. If substance X has a molar mass of 58.45 g/mol, what is the molar heat of fusion for substance X?Use q=nH 13.31 cal/mol 74.00 cal/mol 775.6 cal/mol 19054.7 cal/mol

775.6 cal/mol

A scientist observes that the electrical resistance of a superconducting material drops to zero when the material is cooled to very low temperatures. Which of the following statements best describes what the scientist is observing? The scientist is observing the electrical power of a superconductor. The scientist is observing the temperature of a superconductor. The scientist is observing an intensive property of a superconductor. The scientist is observing an extensive property of a superconductor.

The scientist is observing an intensive property of a superconductor

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

Melting can be best described as a process in which molecules lose kinetic energy and move slowly. lose kinetic energy and remain stationary. gain kinetic energy and escape into the atmosphere. gain enough kinetic energy to get past each other.

gain enough kinetic energy to get past each other

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

What are thermal plasmas? plasmas that have particles that collide infrequently plasmas that reach a temperature equal to their surroundings plasmas that do not reach thermal equilibrium plasmas that have only a few particles ionized at any given moment

plasmas that reach a temperature equal to their surroundings

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

Which low-energy state of condensed matter is characterized by structural rigidity and resistance to changes of shape or volume? gas liquid plasma solid

solid

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

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 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

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

Which energy changes are associated with a liquid boiling? Energy is released, and potential energy decreases. Energy is absorbed, and potential energy increases. Energy is released, and kinetic energy decreases. Energy is absorbed, and kinetic energy increases.

Energy is absorbed, and potential energy increases

Which statement describes a physical property of copper? It reacts with strong acids. It can be reshaped by a force. It ignites at high temperatures. It can combine with oxygen.

It can be reshaped by a force

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

During an endothermic phase change, what happens to the potential energy and the kinetic energy? Potential energy stays the same, and kinetic energy increases. Potential energy increases, and kinetic energy increases. Potential energy decreases, and kinetic energy decreases. Potential energy increases, and kinetic energy stays the same.

Potential energy increases, and kinetic energy stays the same

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

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

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

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 step will decrease the pressure of a gas inside a closed cubical container? increasing the number of moles of gas decreasing the volume of the container increasing the speed of the gas particles decreasing the temperature inside the container

decreasing the temperature inside the container

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

H20 is initially present in a state where its molecules are far apart. During a change of state, its molecules slow down. Which change of state has most likely taken place? from a gas to a liquid from a liquid to a gas from a solid to a liquid from a gas to a plasma

from a gas to a liquid

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

Which term is used to describe the amount of heat that is required to convert 1 mol of a liquid to a gas? dew point boiling point molar heat of fusion molar heat of vaporization

molar heat of vaporization

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