Types of Phase Changes - AP Chemistry
Card 1 of 91
Liquid water at room temperature is cooled to -75O C
Which of the following descriptions applies to the process outlined above?
I: A physical change occurred
II: A chemical change occurred
III: There was a change in entropy
Liquid water at room temperature is cooled to -75O C
Which of the following descriptions applies to the process outlined above?
I: A physical change occurred
II: A chemical change occurred
III: There was a change in entropy
Tap to reveal answer
A physical change is a process where the physical properties of a substance are changed. Here water undergoes a phase change from the more disordered liquid state to the more ordered solid state, which is indeed a physical change. A chemical change describes when a substance undergoes a change in the identity of its constituent molecules. Here although the water has gone from the liquid phase to the solid phase it is still composed only of water molecules so a chemical change has not occured. Entropy describes the degree to which a system is ordered. Here we do have a change in entropy becasue the liquid water was more disordered than the solid water.
A physical change is a process where the physical properties of a substance are changed. Here water undergoes a phase change from the more disordered liquid state to the more ordered solid state, which is indeed a physical change. A chemical change describes when a substance undergoes a change in the identity of its constituent molecules. Here although the water has gone from the liquid phase to the solid phase it is still composed only of water molecules so a chemical change has not occured. Entropy describes the degree to which a system is ordered. Here we do have a change in entropy becasue the liquid water was more disordered than the solid water.
← Didn't Know|Knew It →
A large number of molecules begin moving very fast, rarely bumping into one another, and taking up the entire space available to them. As the temperature drops and the kinetic energy of the particles decreases, the particles move more slowly and run into each other more often. They eventually form a lattice structure, only slightly moving. What is this process called?
A large number of molecules begin moving very fast, rarely bumping into one another, and taking up the entire space available to them. As the temperature drops and the kinetic energy of the particles decreases, the particles move more slowly and run into each other more often. They eventually form a lattice structure, only slightly moving. What is this process called?
Tap to reveal answer
This is a description of condensation from the gas phase to the liquid phase, then freezing from the liquid phase to the solid phase.
This is a description of condensation from the gas phase to the liquid phase, then freezing from the liquid phase to the solid phase.
← Didn't Know|Knew It →
A phase diagram is used to show the phase that a compound will be in depending upon the environmental temperature and pressure.
Carbon dioxide will sublimate from a solid to a gas at room temperature. What would be necessary in order to cause solid carbon dioxide to melt?
A phase diagram is used to show the phase that a compound will be in depending upon the environmental temperature and pressure.
Carbon dioxide will sublimate from a solid to a gas at room temperature. What would be necessary in order to cause solid carbon dioxide to melt?
Tap to reveal answer
At a pressure of one atmosphere, carbon dioxide can only exist in the solid phase or the gaseous phase. Solid carbon dioxide will sublimate at standard conditions.
Raising the temperature will simply make the carbon dioxide sublimate at a faster rate. In order to allow the solid carbon dioxide to melt into the liquid phase, the carbon dioxide must be subjected to a greater amount of pressure. This will shift equilibrium away from the gaseous state and toward the liquid state.
At a pressure of one atmosphere, carbon dioxide can only exist in the solid phase or the gaseous phase. Solid carbon dioxide will sublimate at standard conditions.
Raising the temperature will simply make the carbon dioxide sublimate at a faster rate. In order to allow the solid carbon dioxide to melt into the liquid phase, the carbon dioxide must be subjected to a greater amount of pressure. This will shift equilibrium away from the gaseous state and toward the liquid state.
← Didn't Know|Knew It →
A solution of water is at 0 degrees Celcius and 3atm. The pressure is constantly decreased until it was well below 0.000001atm. What will happen to the solution?
A solution of water is at 0 degrees Celcius and 3atm. The pressure is constantly decreased until it was well below 0.000001atm. What will happen to the solution?
Tap to reveal answer
Whenever you see a problem like this, immediately draw a mental point on the phase diagram to establish your starting conditions. In our case, the conditions fall in the range of the liquid phase of the water. This allows us to eliminate some of our answer options.
Next, determine what change is occuring and on which axis the change is occuring. We are decreasing pressure, so you are going to need to move down on the y-axis towards 0. Draw an imaginary line from the initial point to where the final point should be. In our case, the final pressure is extremely small. This point is not on the y-axis, but we can use our inference/inductive skills to determine that we will pass through the solid phase (ice) as we approach the gas phase (water vapor). Even if you didn't know the water would become vaporized, based on the graph you knew that the liquid phase had to be followed by the solid phase, and only one answer choice has that option.
Whenever you see a problem like this, immediately draw a mental point on the phase diagram to establish your starting conditions. In our case, the conditions fall in the range of the liquid phase of the water. This allows us to eliminate some of our answer options.
Next, determine what change is occuring and on which axis the change is occuring. We are decreasing pressure, so you are going to need to move down on the y-axis towards 0. Draw an imaginary line from the initial point to where the final point should be. In our case, the final pressure is extremely small. This point is not on the y-axis, but we can use our inference/inductive skills to determine that we will pass through the solid phase (ice) as we approach the gas phase (water vapor). Even if you didn't know the water would become vaporized, based on the graph you knew that the liquid phase had to be followed by the solid phase, and only one answer choice has that option.
← Didn't Know|Knew It →
If the boiling point of Selenium (Se) is 
, in what phase must the element be at 
?
If the boiling point of Selenium (Se) is
Tap to reveal answer
We know that the temperature is well below selenium's boiling point, but because we do not know its melting point, we cannot be certain if the temperature has dropped low enough for the element to be a solid.
We know that the temperature is well below selenium's boiling point, but because we do not know its melting point, we cannot be certain if the temperature has dropped low enough for the element to be a solid.
← Didn't Know|Knew It →
Dry ice at room temperature undergoes the following reaction:
What is the name for the type of phase change where a solid changes directly to a gas (without any phase change in between)?
Dry ice at room temperature undergoes the following reaction:
What is the name for the type of phase change where a solid changes directly to a gas (without any phase change in between)?
Tap to reveal answer
When matter changes from one physical state (solid, liquid, gas, or plasma) to a different physical state, a phase change is defined to have occurred.
When a solid changes to a gas, the phase change that occurred is defined as sublimation:
Solid 
Gas
When the opposite occurs and a gas changes to a solid, the phase change is defined as deposition:
Gas 
Solid
When a liquid changes to a gas, the phase change that occurred is defined as vaporization. It is worth noting that there are two types of vaporization: evaporation (when the phase change occurs below the boiling point for the substance) and boiling (when the phase change occurs at or above the substance's boiling point).
Liquid 
Gas
When the opposite occurs and a gas changes to a liquid, the phase change is defined as condensation:
Gas 
Liquid
When a liquid changes to a solid, the phase change that occurred is defined as freezing:
Liquid 
Solid
When the opposite occurs and a solid changes to a liquid, the phase change is defined as melting:
Solid 
Liquid
When a gas changes to a plasma, the phase change that occurred is defined as ionization:
Gas 
Plasma
When the opposite occurs and a plasma changes to a gas, the phase change that occurred is defined as recombination.
Plasma 
Gas
Some may find it easiest to remember the phase changes by memorizing them in pairs. For example freezing and melting both refer to phase changes between solids and liquids. Once that is memorized, the possible phase changes that you have to choose from is reduced from 8 to 2. Also, it may be helpful to think that all the phase changes involving a decrease in entropy (increase in order) deposition, condensation, freezing, and recombination sound like more orderly words than the phase changes involving an increase in entropy (decrease in order) sublimation, vaporization, melting and ionization.
When matter changes from one physical state (solid, liquid, gas, or plasma) to a different physical state, a phase change is defined to have occurred.
When a solid changes to a gas, the phase change that occurred is defined as sublimation:
Solid
When the opposite occurs and a gas changes to a solid, the phase change is defined as deposition:
Gas
When a liquid changes to a gas, the phase change that occurred is defined as vaporization. It is worth noting that there are two types of vaporization: evaporation (when the phase change occurs below the boiling point for the substance) and boiling (when the phase change occurs at or above the substance's boiling point).
Liquid
When the opposite occurs and a gas changes to a liquid, the phase change is defined as condensation:
Gas
When a liquid changes to a solid, the phase change that occurred is defined as freezing:
Liquid
When the opposite occurs and a solid changes to a liquid, the phase change is defined as melting:
Solid
When a gas changes to a plasma, the phase change that occurred is defined as ionization:
Gas
When the opposite occurs and a plasma changes to a gas, the phase change that occurred is defined as recombination.
Plasma
Some may find it easiest to remember the phase changes by memorizing them in pairs. For example freezing and melting both refer to phase changes between solids and liquids. Once that is memorized, the possible phase changes that you have to choose from is reduced from 8 to 2. Also, it may be helpful to think that all the phase changes involving a decrease in entropy (increase in order) deposition, condensation, freezing, and recombination sound like more orderly words than the phase changes involving an increase in entropy (decrease in order) sublimation, vaporization, melting and ionization.
← Didn't Know|Knew It →
How does the boiling point of water at sea level compare to its boiling point at an elevation of 3000 feet?
How does the boiling point of water at sea level compare to its boiling point at an elevation of 3000 feet?
Tap to reveal answer
This question is asking us about the effect that elevation has on the boiling point of water. In order to answer this, we need to have a fundamental understanding of what boiling is, and how it can be affected by factors such as elevation.
Boiling is a type of phase transition in which a liquid is converted into a gas. During this transition, the boiling point is defined as the temperature at which the vapor pressure of the liquid is exactly equal to the atmospheric pressure. Therefore, if the atmospheric pressure is lowered, which happens at increased elevations, then it becomes easier for the liquid to evaporate into the gas phase. Consequently, less energy (and a lower temperature) is needed to push the liquid into the gas phase. As a result, the boiling point of the solution is lowered at increased elevations.
This question is asking us about the effect that elevation has on the boiling point of water. In order to answer this, we need to have a fundamental understanding of what boiling is, and how it can be affected by factors such as elevation.
Boiling is a type of phase transition in which a liquid is converted into a gas. During this transition, the boiling point is defined as the temperature at which the vapor pressure of the liquid is exactly equal to the atmospheric pressure. Therefore, if the atmospheric pressure is lowered, which happens at increased elevations, then it becomes easier for the liquid to evaporate into the gas phase. Consequently, less energy (and a lower temperature) is needed to push the liquid into the gas phase. As a result, the boiling point of the solution is lowered at increased elevations.
← Didn't Know|Knew It →
Liquid water at room temperature is cooled to -75O C
Which of the following descriptions applies to the process outlined above?
I: A physical change occurred
II: A chemical change occurred
III: There was a change in entropy
Liquid water at room temperature is cooled to -75O C
Which of the following descriptions applies to the process outlined above?
I: A physical change occurred
II: A chemical change occurred
III: There was a change in entropy
Tap to reveal answer
A physical change is a process where the physical properties of a substance are changed. Here water undergoes a phase change from the more disordered liquid state to the more ordered solid state, which is indeed a physical change. A chemical change describes when a substance undergoes a change in the identity of its constituent molecules. Here although the water has gone from the liquid phase to the solid phase it is still composed only of water molecules so a chemical change has not occured. Entropy describes the degree to which a system is ordered. Here we do have a change in entropy becasue the liquid water was more disordered than the solid water.
A physical change is a process where the physical properties of a substance are changed. Here water undergoes a phase change from the more disordered liquid state to the more ordered solid state, which is indeed a physical change. A chemical change describes when a substance undergoes a change in the identity of its constituent molecules. Here although the water has gone from the liquid phase to the solid phase it is still composed only of water molecules so a chemical change has not occured. Entropy describes the degree to which a system is ordered. Here we do have a change in entropy becasue the liquid water was more disordered than the solid water.
← Didn't Know|Knew It →
A large number of molecules begin moving very fast, rarely bumping into one another, and taking up the entire space available to them. As the temperature drops and the kinetic energy of the particles decreases, the particles move more slowly and run into each other more often. They eventually form a lattice structure, only slightly moving. What is this process called?
A large number of molecules begin moving very fast, rarely bumping into one another, and taking up the entire space available to them. As the temperature drops and the kinetic energy of the particles decreases, the particles move more slowly and run into each other more often. They eventually form a lattice structure, only slightly moving. What is this process called?
Tap to reveal answer
This is a description of condensation from the gas phase to the liquid phase, then freezing from the liquid phase to the solid phase.
This is a description of condensation from the gas phase to the liquid phase, then freezing from the liquid phase to the solid phase.
← Didn't Know|Knew It →
A phase diagram is used to show the phase that a compound will be in depending upon the environmental temperature and pressure.
Carbon dioxide will sublimate from a solid to a gas at room temperature. What would be necessary in order to cause solid carbon dioxide to melt?
A phase diagram is used to show the phase that a compound will be in depending upon the environmental temperature and pressure.
Carbon dioxide will sublimate from a solid to a gas at room temperature. What would be necessary in order to cause solid carbon dioxide to melt?
Tap to reveal answer
At a pressure of one atmosphere, carbon dioxide can only exist in the solid phase or the gaseous phase. Solid carbon dioxide will sublimate at standard conditions.
Raising the temperature will simply make the carbon dioxide sublimate at a faster rate. In order to allow the solid carbon dioxide to melt into the liquid phase, the carbon dioxide must be subjected to a greater amount of pressure. This will shift equilibrium away from the gaseous state and toward the liquid state.
At a pressure of one atmosphere, carbon dioxide can only exist in the solid phase or the gaseous phase. Solid carbon dioxide will sublimate at standard conditions.
Raising the temperature will simply make the carbon dioxide sublimate at a faster rate. In order to allow the solid carbon dioxide to melt into the liquid phase, the carbon dioxide must be subjected to a greater amount of pressure. This will shift equilibrium away from the gaseous state and toward the liquid state.
← Didn't Know|Knew It →
A solution of water is at 0 degrees Celcius and 3atm. The pressure is constantly decreased until it was well below 0.000001atm. What will happen to the solution?
A solution of water is at 0 degrees Celcius and 3atm. The pressure is constantly decreased until it was well below 0.000001atm. What will happen to the solution?
Tap to reveal answer
Whenever you see a problem like this, immediately draw a mental point on the phase diagram to establish your starting conditions. In our case, the conditions fall in the range of the liquid phase of the water. This allows us to eliminate some of our answer options.
Next, determine what change is occuring and on which axis the change is occuring. We are decreasing pressure, so you are going to need to move down on the y-axis towards 0. Draw an imaginary line from the initial point to where the final point should be. In our case, the final pressure is extremely small. This point is not on the y-axis, but we can use our inference/inductive skills to determine that we will pass through the solid phase (ice) as we approach the gas phase (water vapor). Even if you didn't know the water would become vaporized, based on the graph you knew that the liquid phase had to be followed by the solid phase, and only one answer choice has that option.
Whenever you see a problem like this, immediately draw a mental point on the phase diagram to establish your starting conditions. In our case, the conditions fall in the range of the liquid phase of the water. This allows us to eliminate some of our answer options.
Next, determine what change is occuring and on which axis the change is occuring. We are decreasing pressure, so you are going to need to move down on the y-axis towards 0. Draw an imaginary line from the initial point to where the final point should be. In our case, the final pressure is extremely small. This point is not on the y-axis, but we can use our inference/inductive skills to determine that we will pass through the solid phase (ice) as we approach the gas phase (water vapor). Even if you didn't know the water would become vaporized, based on the graph you knew that the liquid phase had to be followed by the solid phase, and only one answer choice has that option.
← Didn't Know|Knew It →
If the boiling point of Selenium (Se) is , in what phase must the element be at ?
If the boiling point of Selenium (Se) is
Tap to reveal answer
We know that the temperature is well below selenium's boiling point, but because we do not know its melting point, we cannot be certain if the temperature has dropped low enough for the element to be a solid.
We know that the temperature is well below selenium's boiling point, but because we do not know its melting point, we cannot be certain if the temperature has dropped low enough for the element to be a solid.
← Didn't Know|Knew It →
Dry ice at room temperature undergoes the following reaction:
What is the name for the type of phase change where a solid changes directly to a gas (without any phase change in between)?
Dry ice at room temperature undergoes the following reaction:
What is the name for the type of phase change where a solid changes directly to a gas (without any phase change in between)?
Tap to reveal answer
When matter changes from one physical state (solid, liquid, gas, or plasma) to a different physical state, a phase change is defined to have occurred.
When a solid changes to a gas, the phase change that occurred is defined as sublimation:
Solid Gas
When the opposite occurs and a gas changes to a solid, the phase change is defined as deposition:
Gas Solid
When a liquid changes to a gas, the phase change that occurred is defined as vaporization. It is worth noting that there are two types of vaporization: evaporation (when the phase change occurs below the boiling point for the substance) and boiling (when the phase change occurs at or above the substance's boiling point).
Liquid Gas
When the opposite occurs and a gas changes to a liquid, the phase change is defined as condensation:
Gas Liquid
When a liquid changes to a solid, the phase change that occurred is defined as freezing:
Liquid Solid
When the opposite occurs and a solid changes to a liquid, the phase change is defined as melting:
Solid Liquid
When a gas changes to a plasma, the phase change that occurred is defined as ionization:
Gas Plasma
When the opposite occurs and a plasma changes to a gas, the phase change that occurred is defined as recombination.
Plasma Gas
Some may find it easiest to remember the phase changes by memorizing them in pairs. For example freezing and melting both refer to phase changes between solids and liquids. Once that is memorized, the possible phase changes that you have to choose from is reduced from 8 to 2. Also, it may be helpful to think that all the phase changes involving a decrease in entropy (increase in order) deposition, condensation, freezing, and recombination sound like more orderly words than the phase changes involving an increase in entropy (decrease in order) sublimation, vaporization, melting and ionization.
When matter changes from one physical state (solid, liquid, gas, or plasma) to a different physical state, a phase change is defined to have occurred.
When a solid changes to a gas, the phase change that occurred is defined as sublimation:
Solid
When the opposite occurs and a gas changes to a solid, the phase change is defined as deposition:
Gas
When a liquid changes to a gas, the phase change that occurred is defined as vaporization. It is worth noting that there are two types of vaporization: evaporation (when the phase change occurs below the boiling point for the substance) and boiling (when the phase change occurs at or above the substance's boiling point).
Liquid
When the opposite occurs and a gas changes to a liquid, the phase change is defined as condensation:
Gas
When a liquid changes to a solid, the phase change that occurred is defined as freezing:
Liquid
When the opposite occurs and a solid changes to a liquid, the phase change is defined as melting:
Solid
When a gas changes to a plasma, the phase change that occurred is defined as ionization:
Gas
When the opposite occurs and a plasma changes to a gas, the phase change that occurred is defined as recombination.
Plasma
Some may find it easiest to remember the phase changes by memorizing them in pairs. For example freezing and melting both refer to phase changes between solids and liquids. Once that is memorized, the possible phase changes that you have to choose from is reduced from 8 to 2. Also, it may be helpful to think that all the phase changes involving a decrease in entropy (increase in order) deposition, condensation, freezing, and recombination sound like more orderly words than the phase changes involving an increase in entropy (decrease in order) sublimation, vaporization, melting and ionization.
← Didn't Know|Knew It →
How does the boiling point of water at sea level compare to its boiling point at an elevation of 3000 feet?
How does the boiling point of water at sea level compare to its boiling point at an elevation of 3000 feet?
Tap to reveal answer
This question is asking us about the effect that elevation has on the boiling point of water. In order to answer this, we need to have a fundamental understanding of what boiling is, and how it can be affected by factors such as elevation.
Boiling is a type of phase transition in which a liquid is converted into a gas. During this transition, the boiling point is defined as the temperature at which the vapor pressure of the liquid is exactly equal to the atmospheric pressure. Therefore, if the atmospheric pressure is lowered, which happens at increased elevations, then it becomes easier for the liquid to evaporate into the gas phase. Consequently, less energy (and a lower temperature) is needed to push the liquid into the gas phase. As a result, the boiling point of the solution is lowered at increased elevations.
This question is asking us about the effect that elevation has on the boiling point of water. In order to answer this, we need to have a fundamental understanding of what boiling is, and how it can be affected by factors such as elevation.
Boiling is a type of phase transition in which a liquid is converted into a gas. During this transition, the boiling point is defined as the temperature at which the vapor pressure of the liquid is exactly equal to the atmospheric pressure. Therefore, if the atmospheric pressure is lowered, which happens at increased elevations, then it becomes easier for the liquid to evaporate into the gas phase. Consequently, less energy (and a lower temperature) is needed to push the liquid into the gas phase. As a result, the boiling point of the solution is lowered at increased elevations.
← Didn't Know|Knew It →
Liquid water at room temperature is cooled to -75O C
Which of the following descriptions applies to the process outlined above?
I: A physical change occurred
II: A chemical change occurred
III: There was a change in entropy
Liquid water at room temperature is cooled to -75O C
Which of the following descriptions applies to the process outlined above?
I: A physical change occurred
II: A chemical change occurred
III: There was a change in entropy
Tap to reveal answer
A physical change is a process where the physical properties of a substance are changed. Here water undergoes a phase change from the more disordered liquid state to the more ordered solid state, which is indeed a physical change. A chemical change describes when a substance undergoes a change in the identity of its constituent molecules. Here although the water has gone from the liquid phase to the solid phase it is still composed only of water molecules so a chemical change has not occured. Entropy describes the degree to which a system is ordered. Here we do have a change in entropy becasue the liquid water was more disordered than the solid water.
A physical change is a process where the physical properties of a substance are changed. Here water undergoes a phase change from the more disordered liquid state to the more ordered solid state, which is indeed a physical change. A chemical change describes when a substance undergoes a change in the identity of its constituent molecules. Here although the water has gone from the liquid phase to the solid phase it is still composed only of water molecules so a chemical change has not occured. Entropy describes the degree to which a system is ordered. Here we do have a change in entropy becasue the liquid water was more disordered than the solid water.
← Didn't Know|Knew It →
A large number of molecules begin moving very fast, rarely bumping into one another, and taking up the entire space available to them. As the temperature drops and the kinetic energy of the particles decreases, the particles move more slowly and run into each other more often. They eventually form a lattice structure, only slightly moving. What is this process called?
A large number of molecules begin moving very fast, rarely bumping into one another, and taking up the entire space available to them. As the temperature drops and the kinetic energy of the particles decreases, the particles move more slowly and run into each other more often. They eventually form a lattice structure, only slightly moving. What is this process called?
Tap to reveal answer
This is a description of condensation from the gas phase to the liquid phase, then freezing from the liquid phase to the solid phase.
This is a description of condensation from the gas phase to the liquid phase, then freezing from the liquid phase to the solid phase.
← Didn't Know|Knew It →
A phase diagram is used to show the phase that a compound will be in depending upon the environmental temperature and pressure.
Carbon dioxide will sublimate from a solid to a gas at room temperature. What would be necessary in order to cause solid carbon dioxide to melt?
A phase diagram is used to show the phase that a compound will be in depending upon the environmental temperature and pressure.
Carbon dioxide will sublimate from a solid to a gas at room temperature. What would be necessary in order to cause solid carbon dioxide to melt?
Tap to reveal answer
At a pressure of one atmosphere, carbon dioxide can only exist in the solid phase or the gaseous phase. Solid carbon dioxide will sublimate at standard conditions.
Raising the temperature will simply make the carbon dioxide sublimate at a faster rate. In order to allow the solid carbon dioxide to melt into the liquid phase, the carbon dioxide must be subjected to a greater amount of pressure. This will shift equilibrium away from the gaseous state and toward the liquid state.
At a pressure of one atmosphere, carbon dioxide can only exist in the solid phase or the gaseous phase. Solid carbon dioxide will sublimate at standard conditions.
Raising the temperature will simply make the carbon dioxide sublimate at a faster rate. In order to allow the solid carbon dioxide to melt into the liquid phase, the carbon dioxide must be subjected to a greater amount of pressure. This will shift equilibrium away from the gaseous state and toward the liquid state.
← Didn't Know|Knew It →
A solution of water is at 0 degrees Celcius and 3atm. The pressure is constantly decreased until it was well below 0.000001atm. What will happen to the solution?
A solution of water is at 0 degrees Celcius and 3atm. The pressure is constantly decreased until it was well below 0.000001atm. What will happen to the solution?
Tap to reveal answer
Whenever you see a problem like this, immediately draw a mental point on the phase diagram to establish your starting conditions. In our case, the conditions fall in the range of the liquid phase of the water. This allows us to eliminate some of our answer options.
Next, determine what change is occuring and on which axis the change is occuring. We are decreasing pressure, so you are going to need to move down on the y-axis towards 0. Draw an imaginary line from the initial point to where the final point should be. In our case, the final pressure is extremely small. This point is not on the y-axis, but we can use our inference/inductive skills to determine that we will pass through the solid phase (ice) as we approach the gas phase (water vapor). Even if you didn't know the water would become vaporized, based on the graph you knew that the liquid phase had to be followed by the solid phase, and only one answer choice has that option.
Whenever you see a problem like this, immediately draw a mental point on the phase diagram to establish your starting conditions. In our case, the conditions fall in the range of the liquid phase of the water. This allows us to eliminate some of our answer options.
Next, determine what change is occuring and on which axis the change is occuring. We are decreasing pressure, so you are going to need to move down on the y-axis towards 0. Draw an imaginary line from the initial point to where the final point should be. In our case, the final pressure is extremely small. This point is not on the y-axis, but we can use our inference/inductive skills to determine that we will pass through the solid phase (ice) as we approach the gas phase (water vapor). Even if you didn't know the water would become vaporized, based on the graph you knew that the liquid phase had to be followed by the solid phase, and only one answer choice has that option.
← Didn't Know|Knew It →
If the boiling point of Selenium (Se) is , in what phase must the element be at ?
If the boiling point of Selenium (Se) is
Tap to reveal answer
We know that the temperature is well below selenium's boiling point, but because we do not know its melting point, we cannot be certain if the temperature has dropped low enough for the element to be a solid.
We know that the temperature is well below selenium's boiling point, but because we do not know its melting point, we cannot be certain if the temperature has dropped low enough for the element to be a solid.
← Didn't Know|Knew It →
Dry ice at room temperature undergoes the following reaction:
What is the name for the type of phase change where a solid changes directly to a gas (without any phase change in between)?
Dry ice at room temperature undergoes the following reaction:
What is the name for the type of phase change where a solid changes directly to a gas (without any phase change in between)?
Tap to reveal answer
When matter changes from one physical state (solid, liquid, gas, or plasma) to a different physical state, a phase change is defined to have occurred.
When a solid changes to a gas, the phase change that occurred is defined as sublimation:
Solid Gas
When the opposite occurs and a gas changes to a solid, the phase change is defined as deposition:
Gas Solid
When a liquid changes to a gas, the phase change that occurred is defined as vaporization. It is worth noting that there are two types of vaporization: evaporation (when the phase change occurs below the boiling point for the substance) and boiling (when the phase change occurs at or above the substance's boiling point).
Liquid Gas
When the opposite occurs and a gas changes to a liquid, the phase change is defined as condensation:
Gas Liquid
When a liquid changes to a solid, the phase change that occurred is defined as freezing:
Liquid Solid
When the opposite occurs and a solid changes to a liquid, the phase change is defined as melting:
Solid Liquid
When a gas changes to a plasma, the phase change that occurred is defined as ionization:
Gas Plasma
When the opposite occurs and a plasma changes to a gas, the phase change that occurred is defined as recombination.
Plasma Gas
Some may find it easiest to remember the phase changes by memorizing them in pairs. For example freezing and melting both refer to phase changes between solids and liquids. Once that is memorized, the possible phase changes that you have to choose from is reduced from 8 to 2. Also, it may be helpful to think that all the phase changes involving a decrease in entropy (increase in order) deposition, condensation, freezing, and recombination sound like more orderly words than the phase changes involving an increase in entropy (decrease in order) sublimation, vaporization, melting and ionization.
When matter changes from one physical state (solid, liquid, gas, or plasma) to a different physical state, a phase change is defined to have occurred.
When a solid changes to a gas, the phase change that occurred is defined as sublimation:
Solid
When the opposite occurs and a gas changes to a solid, the phase change is defined as deposition:
Gas
When a liquid changes to a gas, the phase change that occurred is defined as vaporization. It is worth noting that there are two types of vaporization: evaporation (when the phase change occurs below the boiling point for the substance) and boiling (when the phase change occurs at or above the substance's boiling point).
Liquid
When the opposite occurs and a gas changes to a liquid, the phase change is defined as condensation:
Gas
When a liquid changes to a solid, the phase change that occurred is defined as freezing:
Liquid
When the opposite occurs and a solid changes to a liquid, the phase change is defined as melting:
Solid
When a gas changes to a plasma, the phase change that occurred is defined as ionization:
Gas
When the opposite occurs and a plasma changes to a gas, the phase change that occurred is defined as recombination.
Plasma
Some may find it easiest to remember the phase changes by memorizing them in pairs. For example freezing and melting both refer to phase changes between solids and liquids. Once that is memorized, the possible phase changes that you have to choose from is reduced from 8 to 2. Also, it may be helpful to think that all the phase changes involving a decrease in entropy (increase in order) deposition, condensation, freezing, and recombination sound like more orderly words than the phase changes involving an increase in entropy (decrease in order) sublimation, vaporization, melting and ionization.
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