Phases of Matter - High School Chemistry
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Distillation requires which of the following?
Distillation requires which of the following?
Distillation is the process by which liquids are purified of impurities. Distillation first requires vaporization of liquids to become pure gases. The gases are then cooled and turned back into pure liquids via condensation into a separate container. A good distillation will remove all impurities from the liquid. This is why distilled water is used for chemical solutions; it does not contain ions or other impurities that could interfere with reaction.
Distillation is the process by which liquids are purified of impurities. Distillation first requires vaporization of liquids to become pure gases. The gases are then cooled and turned back into pure liquids via condensation into a separate container. A good distillation will remove all impurities from the liquid. This is why distilled water is used for chemical solutions; it does not contain ions or other impurities that could interfere with reaction.
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Which of the following occurs during vaporization?
Which of the following occurs during vaporization?
Vaporization refers to the phase change from liquid to gas, also known as evaporation. When becoming a gas, atoms spread out and expand to fill whatever container they are in. Conservation of mass hold that atoms are never created nor destroyed. Atoms becoming more organized and forming a more rigid shape describes a phase change toward becoming solid.
Vaporization refers to the phase change from liquid to gas, also known as evaporation. When becoming a gas, atoms spread out and expand to fill whatever container they are in. Conservation of mass hold that atoms are never created nor destroyed. Atoms becoming more organized and forming a more rigid shape describes a phase change toward becoming solid.
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During the process of freezing, what do you know about changes in the temperature and entropy of water?
During the process of freezing, what do you know about changes in the temperature and entropy of water?
The temperature of a sample during the process of a phase change will remain constant. Even though heat may be added or removed during this process, it is utilized to directly impact the formation and breaking of intermolecular interactions within the sample. The result is a change in the internal properties of the sample (the phase), with no actual change in temperature.
When a substance freezes it transitions from a liquid to a solid. The result is a much more ordered structure, as opposed to the fluidity associated with the liquid phase. Increasing order corresponds to a decrease in entropy because entropy is a measure of disorder.
The temperature of a sample during the process of a phase change will remain constant. Even though heat may be added or removed during this process, it is utilized to directly impact the formation and breaking of intermolecular interactions within the sample. The result is a change in the internal properties of the sample (the phase), with no actual change in temperature.
When a substance freezes it transitions from a liquid to a solid. The result is a much more ordered structure, as opposed to the fluidity associated with the liquid phase. Increasing order corresponds to a decrease in entropy because entropy is a measure of disorder.
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The following is the phase diagram for 
.
What state change is occurring on from point A to point G?
The following is the phase diagram for
What state change is occurring on from point A to point G?
The section point A is in is the solid portion of the phase diagram. At low temperatures and high pressures, substances form solids. Increasing the temperature while keeping pressure high, ice melts into water. Point G is in the liquid portion of the phase diagram.
The section point A is in is the solid portion of the phase diagram. At low temperatures and high pressures, substances form solids. Increasing the temperature while keeping pressure high, ice melts into water. Point G is in the liquid portion of the phase diagram.
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Which of the following is associated with freezing, for most substances?
Which of the following is associated with freezing, for most substances?
When a substance freezes, the average kinetic energy of the particles decreases. This means that the particles will move more slowly. Most substances also contract when they cool to increase the organization of the molecules (crystallization). Thus, for most substances, particles will get closer together as they freeze. One notable exception is water, which expands as it freezes (the same mass of water that freezes into ice will float in liquid water due to an increase in volume).
When a substance freezes, the average kinetic energy of the particles decreases. This means that the particles will move more slowly. Most substances also contract when they cool to increase the organization of the molecules (crystallization). Thus, for most substances, particles will get closer together as they freeze. One notable exception is water, which expands as it freezes (the same mass of water that freezes into ice will float in liquid water due to an increase in volume).
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Which of the following is not a phase transition?
Which of the following is not a phase transition?
There are six phase changes possible. Transition from solid to gas is sublimation, while transition from gas to solid is deposition. Transition from solid to liquid is melting, while transition from liquid to solid is fusion (freezing). Transition from gas to liquid is condensation, while transition from liquid to gas is vaporization (boiling). Each phase transition is considered a physical change, not a chemical change, because the identity of the compound remains unchanged.
Decomposition is a reaction type that involves a reactant being broken down into two or more products. This is a chemical change, since the identity of the reactant is changed.
There are six phase changes possible. Transition from solid to gas is sublimation, while transition from gas to solid is deposition. Transition from solid to liquid is melting, while transition from liquid to solid is fusion (freezing). Transition from gas to liquid is condensation, while transition from liquid to gas is vaporization (boiling). Each phase transition is considered a physical change, not a chemical change, because the identity of the compound remains unchanged.
Decomposition is a reaction type that involves a reactant being broken down into two or more products. This is a chemical change, since the identity of the reactant is changed.
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Heating curves are used to graph the change in temperature as heat is added to a system. A solid system is heated until it is converted to a gas, and the heating curve is graphed. Why does the heating curve have two horizontal plateaus?
Heating curves are used to graph the change in temperature as heat is added to a system. A solid system is heated until it is converted to a gas, and the heating curve is graphed. Why does the heating curve have two horizontal plateaus?
A heating curve shows the transition of a solid to a liquid to a gas. A solid, liquid, or gas can exist within a range of varying temperatures, but when a solid is turning into a liquid, or a liquid is turning into a gas, the temperature stays constant. This is the point at which there is a mixture of solids and liquids or liquids and gases within the system. Heat is still being applied to the system, but instead of raising the temperature the heat is converting from one phase to another. Temperature will remain constant during a phase transition until all of the substance has been converted to the final phase.
A heating curve shows the transition of a solid to a liquid to a gas. A solid, liquid, or gas can exist within a range of varying temperatures, but when a solid is turning into a liquid, or a liquid is turning into a gas, the temperature stays constant. This is the point at which there is a mixture of solids and liquids or liquids and gases within the system. Heat is still being applied to the system, but instead of raising the temperature the heat is converting from one phase to another. Temperature will remain constant during a phase transition until all of the substance has been converted to the final phase.
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What phase is determined by the inability to distinguish liquid from gas?
What phase is determined by the inability to distinguish liquid from gas?
A phase diagram is used to show what phases of a certain compound exist at given temperatures and pressures. Decreasing pressure and increasing temperature generally cause the compound to favor the gaseous phase, while increasing pressure and decreasing temperature generally cause the compound to favor the solid phase.
On a phase diagram, there is a point known as the critical point. This point gives coordinate at which gases and liquids stop being distinguishable from one another. If pressure or temperature is increased above this point, the sample will enter a state that is fluid, but is neither gas nor liquid. Remember that both gases and liquids have fluid properties. This state of matter is known as a supercritical fluid.
A phase diagram is used to show what phases of a certain compound exist at given temperatures and pressures. Decreasing pressure and increasing temperature generally cause the compound to favor the gaseous phase, while increasing pressure and decreasing temperature generally cause the compound to favor the solid phase.
On a phase diagram, there is a point known as the critical point. This point gives coordinate at which gases and liquids stop being distinguishable from one another. If pressure or temperature is increased above this point, the sample will enter a state that is fluid, but is neither gas nor liquid. Remember that both gases and liquids have fluid properties. This state of matter is known as a supercritical fluid.
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On an energy diagram for water, in which temperature is graphed against energy input, the temperature of liquid water will increase up to 
. At this point, the temperature will plateau even as more energy is added. After this brief plateau, the temperature of the water will rise above 
.
What value is given by the length of this plateau along the x-axis?
On an energy diagram for water, in which temperature is graphed against energy input, the temperature of liquid water will increase up to
What value is given by the length of this plateau along the x-axis?
Upon reaching 
, the temperature of the water will stop increasing and stay at 
for a brief time. At this point, the energy being added to the water is being used to break the intermolecular bonds between the water molecules. Once the bonds are broken, the water will have fully entered the gas phase, and the water vapor will continue to increase in temperature.
The amount of heat needed to break the intermolecular bonds is called the enthalpy of vaporization. During the plateau, heat is being added and immediately used to break bonds. The length of the plateau corresponds to the amount of heat added during this period, which will equal the enthalpy of vaporization.
Upon reaching
The amount of heat needed to break the intermolecular bonds is called the enthalpy of vaporization. During the plateau, heat is being added and immediately used to break bonds. The length of the plateau corresponds to the amount of heat added during this period, which will equal the enthalpy of vaporization.
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Carbon dioxide does not have a liquid phase under standard conditions. Instead, it transitions from a solid to a gas as temperature increases. Based on this information, which of the following statements is true?
Carbon dioxide does not have a liquid phase under standard conditions. Instead, it transitions from a solid to a gas as temperature increases. Based on this information, which of the following statements is true?
The triple point of a compound refers to the temperature and pressure conditions under which a substance exists in all three phases of matter simultaneously. If the pressure is below that of the triple point, the compound will only exist as a solid or a gas, depending on the temperature of the compound. As a result, standard pressure is below carbon dioxide's triple point since it cannot exist as a liquid.
The triple point of a compound refers to the temperature and pressure conditions under which a substance exists in all three phases of matter simultaneously. If the pressure is below that of the triple point, the compound will only exist as a solid or a gas, depending on the temperature of the compound. As a result, standard pressure is below carbon dioxide's triple point since it cannot exist as a liquid.
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What does critical temperature describe?
What does critical temperature describe?
A phase diagram is divided into three regions based on temperature and pressure conditions. Solids exist at low temperatures and high pressures. Liquids exist at medium temperatures and relatively high pressures. Gases exist at high temperatures and low pressures. The lines dividing each region show the conditions required to change between phases, such as the boiling point or freezing point of the compound.
The critical point, or critical temperature, refers to the terminal point on the segment that divides the liquid and gas regions of the phase diagram. Beyond this point, liquids and gases become indistinguishable. The critical point occurs at a very high temperature and pressure. Increasing the termperature beyond this point cannot result in a phase change, regardless of pressure change.
A phase diagram is divided into three regions based on temperature and pressure conditions. Solids exist at low temperatures and high pressures. Liquids exist at medium temperatures and relatively high pressures. Gases exist at high temperatures and low pressures. The lines dividing each region show the conditions required to change between phases, such as the boiling point or freezing point of the compound.
The critical point, or critical temperature, refers to the terminal point on the segment that divides the liquid and gas regions of the phase diagram. Beyond this point, liquids and gases become indistinguishable. The critical point occurs at a very high temperature and pressure. Increasing the termperature beyond this point cannot result in a phase change, regardless of pressure change.
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Which of the following gases will diffuse the quickest through a small hole?
Which of the following gases will diffuse the quickest through a small hole?
Gases with high higher molecular weights are going to move at slower velocities. At a given temperature, all gases have the same average kinetic energy. For this to remain true, larger molecules must move slower since they have greater masses.
The gas to diffuse quickest will have the smallest molecular weight. In this case, that gas is hydrogen.
Gases with high higher molecular weights are going to move at slower velocities. At a given temperature, all gases have the same average kinetic energy. For this to remain true, larger molecules must move slower since they have greater masses.
The gas to diffuse quickest will have the smallest molecular weight. In this case, that gas is hydrogen.
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Which of the following is a physical property of gases?
Which of the following is a physical property of gases?
There are six primary properties of gases: expansion, fluidity, low density, compressibility, diffusion, and effusion.
Expansion suggests that gases have no defined shape and will expand to fill a given space, without significant intermolecular interaction. Fluidity is a property of both gases and liquids and describes the relatively low attraction between particles. This allows the gas molecules to move past one another, creating the "fluid" nature of the gas. Low density of gases is linked to gas expansion. Gases will expand to the greatest extent possible, resulting in low mass per unit volume ratios. Compressibility is also linked to expansion and the indefinite shape of the gas, essentially suggesting that the distance between particles can be reduced if pressure is increased. Diffusion and effusion are both linked to the movement of gases. Diffusion means that gases can spread out and mix within a given space, while effusion means that gases can pass through a small opening at a given rate.
Some of these properties are unique to gases, while others are shared between gases and liquids. Gases have virtually no physical properties in common with solids.
There are six primary properties of gases: expansion, fluidity, low density, compressibility, diffusion, and effusion.
Expansion suggests that gases have no defined shape and will expand to fill a given space, without significant intermolecular interaction. Fluidity is a property of both gases and liquids and describes the relatively low attraction between particles. This allows the gas molecules to move past one another, creating the "fluid" nature of the gas. Low density of gases is linked to gas expansion. Gases will expand to the greatest extent possible, resulting in low mass per unit volume ratios. Compressibility is also linked to expansion and the indefinite shape of the gas, essentially suggesting that the distance between particles can be reduced if pressure is increased. Diffusion and effusion are both linked to the movement of gases. Diffusion means that gases can spread out and mix within a given space, while effusion means that gases can pass through a small opening at a given rate.
Some of these properties are unique to gases, while others are shared between gases and liquids. Gases have virtually no physical properties in common with solids.
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Which of the following gas laws can be used to determine the total pressure of a mixture of gases?
Which of the following gas laws can be used to determine the total pressure of a mixture of gases?
Each gas in a mixture of gases exerts its own pressure independently of the other gases present; therefore the pressure of each gas within a mixture is called the partial pressure of the gas.
Dalton's law of partial pressures states that the total pressure of a mixture of gases is equal to the sum of the partial pressures of the component gases. This can be expressed mathematically as follows:
Boyle's law and Gay-Lussac's law can help determine pressure in varying volumes and temperatures, respectively, but can only be useful with regard to the total pressure of the system. The second law of thermodynamics is not related to gas properties, and states that the entropy of the universe is constantly increasing.
Each gas in a mixture of gases exerts its own pressure independently of the other gases present; therefore the pressure of each gas within a mixture is called the partial pressure of the gas.
Dalton's law of partial pressures states that the total pressure of a mixture of gases is equal to the sum of the partial pressures of the component gases. This can be expressed mathematically as follows:
Boyle's law and Gay-Lussac's law can help determine pressure in varying volumes and temperatures, respectively, but can only be useful with regard to the total pressure of the system. The second law of thermodynamics is not related to gas properties, and states that the entropy of the universe is constantly increasing.
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Which of the following is not a characteristic of gases?
Which of the following is not a characteristic of gases?
Gases are able to effuse though small pinhole openings, and diffuse into empty spaces from high to low concentrations. The kinetic energy of gas molecules is dependent on temperature. Higher temperatures cause in increase in the kinetic energy of the particles.
Gases have very low densities. Density is a measure of mass per unit volume. Since the gas molecules are spread out over a much larger distance compared to liquids and solids, their densities are very low.
Gases are able to effuse though small pinhole openings, and diffuse into empty spaces from high to low concentrations. The kinetic energy of gas molecules is dependent on temperature. Higher temperatures cause in increase in the kinetic energy of the particles.
Gases have very low densities. Density is a measure of mass per unit volume. Since the gas molecules are spread out over a much larger distance compared to liquids and solids, their densities are very low.
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A container filled with fluorine gas and neon gas and has a total pressure of 
. There are 
of fluorine gas in the container, and the fluorine gas exerts a pressure of 
.
Based on this, what is the mass of neon in the container?
A container filled with fluorine gas and neon gas and has a total pressure of
Based on this, what is the mass of neon in the container?
The partial pressures of each gas are not dependent on their masses, but the total number of moles of gas in the container. Since we know how much pressure the fluorine gas exerts on the container, we can solve for the molar fraction of fluorine gas in the container.
In other words, 62.5% of the gas in the container is fluorine gas. Knowing this, we can solve for how many moles of neon gas are in the container.
50 grams of fluorine gas is equal to 1.32 moles of fluorine gas. If this molar amount accounts for 62.5% of the gas in the container, we can solve for the total number of moles in the container:
Since there are only two gases in the container, we can solve for the number of moles of neon gas in the container.
Since there are .79 moles of neon gas, we can multiply by the molar mass and find the toal mass of the neon gas in the container:
The partial pressures of each gas are not dependent on their masses, but the total number of moles of gas in the container. Since we know how much pressure the fluorine gas exerts on the container, we can solve for the molar fraction of fluorine gas in the container.
In other words, 62.5% of the gas in the container is fluorine gas. Knowing this, we can solve for how many moles of neon gas are in the container.
50 grams of fluorine gas is equal to 1.32 moles of fluorine gas. If this molar amount accounts for 62.5% of the gas in the container, we can solve for the total number of moles in the container:
Since there are only two gases in the container, we can solve for the number of moles of neon gas in the container.
Since there are .79 moles of neon gas, we can multiply by the molar mass and find the toal mass of the neon gas in the container:
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Assume air contains 21% oxygen and 79% nitrogen.
If air is compressed to 5.5atm, what is the partial pressure of the oxygen?
Assume air contains 21% oxygen and 79% nitrogen.
If air is compressed to 5.5atm, what is the partial pressure of the oxygen?
Use Dalton's law of partial pressure:
Where 
is the partial pressure of oxygen and 
is the mole fraction of oxygen. Plug in known values and solve.
Use Dalton's law of partial pressure:
Where
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Mass density is the grams of gas per volume, while number density is the number of molecules per volume.
Which of the following has the highest number density, if each gas occupies the same volume?
Mass density is the grams of gas per volume, while number density is the number of molecules per volume.
Which of the following has the highest number density, if each gas occupies the same volume?
Divide each component by their molecular weight to obtain the number of moles. The hydrogen gas has the most moles that occupy the same volume. Remember that of the answer choices, hydrogen, and oxygen are both diatomic gasses, which needs to be taken into account when calculating the number of moles. For simplicity, let's assume we have 1L of each gas.
As an example, let's calculate the number density for oxygen to show that it is indeed less than that for hydrogen.
Divide each component by their molecular weight to obtain the number of moles. The hydrogen gas has the most moles that occupy the same volume. Remember that of the answer choices, hydrogen, and oxygen are both diatomic gasses, which needs to be taken into account when calculating the number of moles. For simplicity, let's assume we have 1L of each gas.
As an example, let's calculate the number density for oxygen to show that it is indeed less than that for hydrogen.
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Which phase of matter has a definite volume, but no definite shape?
Which phase of matter has a definite volume, but no definite shape?
Liquids have a few similar properties to solids. They are not easily compressible and they have a definite constant volume. Unlike solids, however, liquids do not have a definite shape and conform to the structure that contains them. Solids maintain a constant shape.
Gases have no definite shape or volume.
Liquids have a few similar properties to solids. They are not easily compressible and they have a definite constant volume. Unlike solids, however, liquids do not have a definite shape and conform to the structure that contains them. Solids maintain a constant shape.
Gases have no definite shape or volume.
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What is the freezing point of three moles of HCl dissolved into 1kg of water?
What is the freezing point of three moles of HCl dissolved into 1kg of water?
Freezing point depression refers to the phenomenon that occurs when the freezing point of a solution is decreased due to the presence of ions or molecules. The freezing point depression is given by the formula:
refers to the van't Hoff factor, which is the number of ions created by dissolving a single molecule of the solute. In this case, the van't Hoff factor is two because HCl will create two ions per molecule in solution.
referes to the molality, which is the moles of solute per kilogram of solvent. We can rewrite our equation in these terms:
We know all of these terms, allowing us to solve:
This tells us that the freezing point of the solution is 11.16 degrees less than the freezing point of pure water.
Freezing point depression refers to the phenomenon that occurs when the freezing point of a solution is decreased due to the presence of ions or molecules. The freezing point depression is given by the formula:
We know all of these terms, allowing us to solve:
This tells us that the freezing point of the solution is 11.16 degrees less than the freezing point of pure water.
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