All ACT Science Resources
Example Questions
Example Question #111 : Chemistry
Chemists can model how solids, liquids, and gases behave at different temperatures and pressures with a graph called a phase diagram. When the pressure and temperature are simultaneously known, a scientist can predict whether the material will be in a specific state. The diagram is divided into sections depending on the phase and the lines between sections represent phase transitions occurring between two or more separate phases.
In general, solids of neatly stacked molecules exist when temperatures are low and pressures are intermediate. These values decrease the kinetic energy of the molecules enough to allow for attractive forces to begin the stacking process. Liquids, by contrast, are found at intermediate pressures and temperatures. The temperature is high enough to impart enough kinetic energy to prevent solid formation and the pressure is high enough to prevent the liquid from becoming a gas. Finally, a gas forms at low pressures and high temperatures. The high level of kinetic energy prevents molecules from associating with one another.
Materials can undergo processes called phase transitions, meaning they can transition from one phase to another. The transition from a solid to a liquid is called melting, while the reverse transition is called freezing. Vaporization occurs when a liquid becomes a gas, while condensation occurs when a gas becomes a liquid. Finally, in a process called sublimation, a solid can directly become a gas without passing through a liquid phase. Additionally, when a gas directly becomes a solid, this is known as deposition.
The phase transition occuring at Point C where a substance moves from area one to area three is called __________.
Deposition
Condensation
Vaporization
Sublimation
Sublimation
Paragraph three helps us understand that sublimation occurs when a substance transitions from the solid phase directly to the gaseous phase. Using the information also provided in paragraph two, we can see that area one is where the substance is in solid form (low temperature with intermediate pressure) and area three is where the substance is in gaseous form (high temperature and low pressure).
Example Question #112 : Chemistry
Chemists can model how solids, liquids, and gases behave at different temperatures and pressures with a graph called a phase diagram. When the pressure and temperature are simultaneously known, a scientist can predict whether the material will be in a specific state. The diagram is divided into sections depending on the phase and the lines between sections represent phase transitions occurring between two or more separate phases.
In general, solids of neatly stacked molecules exist when temperatures are low and pressures are intermediate. These values decrease the kinetic energy of the molecules enough to allow for attractive forces to begin the stacking process. Liquids, by contrast, are found at intermediate pressures and temperatures. The temperature is high enough to impart enough kinetic energy to prevent solid formation and the pressure is high enough to prevent the liquid from becoming a gas. Finally, a gas forms at low pressures and high temperatures. The high level of kinetic energy prevents molecules from associating with one another.
Materials can undergo processes called phase transitions, meaning they can transition from one phase to another. The transition from a solid to a liquid is called melting, while the reverse transition is called freezing. Vaporization occurs when a liquid becomes a gas, while condensation occurs when a gas becomes a liquid. Finally, in a process called sublimation, a solid can directly become a gas without passing through a liquid phase. Additionally, when a gas directly becomes a solid, this is known as deposition.
The phase transition occuring at Point A where a substance goes from its phase in area two to its phase in area one is best described as __________.
Boiling
Vaporization
Freezing
Condensation
Freezing
Paragraph three helps us understand that as a material transitions from a liquid to a solid, it is freezing. We can determine that area two is the liquid phase by noting that it is at intermediate pressure and temperature. Additionally, we can determine that area one is a solid by noting the low temperature and intermediate pressure.
Example Question #113 : Chemistry
Chemists can model how solids, liquids, and gases behave at different temperatures and pressures with a graph called a phase diagram. When the pressure and temperature are simultaneously known, a scientist can predict whether the material will be in a specific state. The diagram is divided into sections depending on the phase and the lines between sections represent phase transitions occurring between two or more separate phases.
In general, solids of neatly stacked molecules exist when temperatures are low and pressures are intermediate. These values decrease the kinetic energy of the molecules enough to allow for attractive forces to begin the stacking process. Liquids, by contrast, are found at intermediate pressures and temperatures. The temperature is high enough to impart enough kinetic energy to prevent solid formation and the pressure is high enough to prevent the liquid from becoming a gas. Finally, a gas forms at low pressures and high temperatures. The high level of kinetic energy prevents molecules from associating with one another.
Materials can undergo processes called phase transitions, meaning they can transition from one phase to another. The transition from a solid to a liquid is called melting, while the reverse transition is called freezing. Vaporization occurs when a liquid becomes a gas, while condensation occurs when a gas becomes a liquid. Finally, in a process called sublimation, a solid can directly become a gas without passing through a liquid phase. Additionally, when a gas directly becomes a solid, this is known as deposition.
At Point D, the material is most likley in what phase(s)?
Solid
Solid, Liquid, and Gas
Liquid
Gas
Solid, Liquid, and Gas
The last sentence of the first paragraph gives us an indication of what Point D may represent. We are told that the lines between sections represents a phase transition occuring between those respective phases. At Point D, however, we see that all three phases intersect, implying that all phase transitions are occuring simulaneously at this point and thus all states of the material may be present.
Example Question #114 : Chemistry
Chemists can model how solids, liquids, and gases behave at different temperatures and pressures with a graph called a phase diagram. When the pressure and temperature are simultaneously known, a scientist can predict whether the material will be in a specific state. The diagram is divided into sections depending on the phase and the lines between sections represent phase transitions occurring between two or more separate phases.
In general, solids of neatly stacked molecules exist when temperatures are low and pressures are intermediate. These values decrease the kinetic energy of the molecules enough to allow for attractive forces to begin the stacking process. Liquids, by contrast, are found at intermediate pressures and temperatures. The temperature is high enough to impart enough kinetic energy to prevent solid formation and the pressure is high enough to prevent the liquid from becoming a gas. Finally, a gas forms at low pressures and high temperatures. The high level of kinetic energy prevents molecules from associating with one another.
Materials can undergo processes called phase transitions, meaning they can transition from one phase to another. The transition from a solid to a liquid is called melting, while the reverse transition is called freezing. Vaporization occurs when a liquid becomes a gas, while condensation occurs when a gas becomes a liquid. Finally, in a process called sublimation, a solid can directly become a gas without passing through a liquid phase. Additionally, when a gas directly becomes a solid, this is known as deposition.
Solid carbon dioxide is commonly stored in freezing cold, low pressure rooms to prevent loss of the material. If the temperature in the room slowly warmed, the solid carbon dioxide would most likely become what?
Cannot Be Determined
Gas
Liquid
Remain Solid
Gas
This question asks us to look at the figure to see what would happen if we keep the pressure constant but increase the temperature of the room storing the dry ice. We can see that as we move left to right across the figure, without changing pressure, that we cross the phase transition line for sublimation/deposition. Becasue the temperature is warming, we know we are going from a solid directly to a gas by the process of sublimation.
Example Question #115 : Chemistry
Chemists can model how solids, liquids, and gases behave at different temperatures and pressures with a graph called a phase diagram. When the pressure and temperature are simultaneously known, a scientist can predict whether the material will be in a specific state. The diagram is divided into sections depending on the phase and the lines between sections represent phase transitions occurring between two or more separate phases.
In general, solids of neatly stacked molecules exist when temperatures are low and pressures are intermediate. These values decrease the kinetic energy of the molecules enough to allow for attractive forces to begin the stacking process. Liquids, by contrast, are found at intermediate pressures and temperatures. The temperature is high enough to impart enough kinetic energy to prevent solid formation and the pressure is high enough to prevent the liquid from becoming a gas. Finally, a gas forms at low pressures and high temperatures. The high level of kinetic energy prevents molecules from associating with one another.
Materials can undergo processes called phase transitions, meaning they can transition from one phase to another. The transition from a solid to a liquid is called melting, while the reverse transition is called freezing. Vaporization occurs when a liquid becomes a gas, while condensation occurs when a gas becomes a liquid. Finally, in a process called sublimation, a solid can directly become a gas without passing through a liquid phase. Additionally, when a gas directly becomes a solid, this is known as deposition.
What property most likely allows for molecules to stack neatly when freezing?
Reduction in Kinetic Energy
Repulsive Forces
Symmetric Molecules
Increase in Potential Energy
Reduction in Kinetic Energy
The beginning of paragraph two helps guide our thinking for this question. We know that molecules stack nearly when temperatures are low and pressures are intermediate. Decreasing kinetic energy allows the molecules to remain closer together and for the attractive forces that are present to initiate the stacking process. Thus, the beginning of the stacking process depends on the reduction in kinetic energy.
Example Question #111 : Chemistry
The Ideal Gas Law is as follows:
is pressure as measured in Pascals, is volume as measured in cubic meters, is the number of moles of the gas, is the gas constant known as 8.314 Joules per mole times Kelvin, and is the temperature measured in Kelvin.
A class of students began studying the Ideal Gas Law and how the Pressure and the Volume relate to one another. They took 20 moles of a sample gas and kept the room at a temperature of 300 Kelvin. They then used different sized containers of the gas to limit and expand the volume. At each different volume, they measure the pressure of the gas on its container. The table they made from their results is seen in table 1.
Temperature in Kelvin |
Pressure Measured in Pascals |
|
|
200 Kelvin |
16, 628 Pascals |
400 Kelvin |
33, 256 Pascals |
600 Kelvin |
49, 884 Pascals |
800 Kelvin |
66, 512 Pascals |
TABLE 1
FIGURE 1
The graph the students made based on the data is seen in Figure 1.
Pressure is created by the movement of the gas molecules pushing against a container. 0 Kelvin is known as absolute 0, the temperature at which all molecule movement theoretically stops.
Will the pressure of a gas ever be according to this graph?
No, because the plots on the graph do not support the theory of absolute zero.
Yes, but only if the temperature in Kelvin gets so high that the molecules move fast enough to explode their container.
Yes, but only if Kelvin is converted to Celsius since water freezes at 0 degrees Celsius.
No, because gas molecules' movement does not relate to temperature.
Yes, but only if the theory holds true and the temperature reaches absolute 0 to stop all molecule movement.
Yes, but only if the theory holds true and the temperature reaches absolute 0 to stop all molecule movement.
The plots on the graph as well as the equation of the Ideal Gas Law do support the idea that when temperature is equal to zero, so is pressure.
Example Question #112 : Chemistry
The Ideal Gas Law is as follows:
is pressure as measured in Pascals, is volume as measured in cubic meters, is the number of moles of the gas, is the gas constant known as 8.314 Joules per mole times Kelvin, and is the temperature measured in Kelvin.
A class of students began studying the Ideal Gas Law and how the Pressure and the Volume relate to one another. They took 20 moles of a sample gas and kept the room at a temperature of 300 Kelvin. They then used different sized containers of the gas to limit and expand the volume. At each different volume, they measure the pressure of the gas on its container. The table they made from their results is seen in table 1.
Temperature in Kelvin |
Pressure Measured in Pascals |
|
|
200 Kelvin |
16, 628 Pascals |
400 Kelvin |
33, 256 Pascals |
600 Kelvin |
49, 884 Pascals |
800 Kelvin |
66, 512 Pascals |
TABLE 1
FIGURE 1
The graph the students made based on the data is seen in Figure 1.
Pressure is created by the movement of the gas molecules pushing against a container. 0 Kelvin is known as absolute 0, the temperature at which all molecule movement theoretically stops.
What would the pressure be if the temperature of the gas was increased to 273 Kelvin?
The answer cannot be determined from the equation
The Ideal Gas Law is given with pressure measured in Pascals. If the number 273 Kelvin was plugged into the equation, the number of Pascals that would be .
.
Example Question #113 : Chemistry
The Ideal Gas Law is as follows:
is pressure as measured in Pascals, is volume as measured in cubic meters, is the number of moles of the gas, is the gas constant known as 8.314 Joules per mole times Kelvin, and is the temperature measured in Kelvin.
A class of students began studying the Ideal Gas Law and how the Pressure and the Volume relate to one another. They took 20 moles of a sample gas and kept the room at a temperature of 300 Kelvin. They then used different sized containers of the gas to limit and expand the volume. At each different volume, they measure the pressure of the gas on its container. The table they made from their results is seen in table 1.
Temperature in Kelvin |
Pressure Measured in Pascals |
|
|
200 Kelvin |
16, 628 Pascals |
400 Kelvin |
33, 256 Pascals |
600 Kelvin |
49, 884 Pascals |
800 Kelvin |
66, 512 Pascals |
TABLE 1
FIGURE 1
The graph the students made based on the data is seen in Figure 1.
Pressure is created by the movement of the gas molecules pushing against a container. 0 Kelvin is known as absolute 0, the temperature at which all molecule movement theoretically stops.
If the equation for converting Kelvin to degrees Fahrenheit is:
at what temperature Fahrenheit is the pressure
When the given number of Pascals is put into the Ideal Gas Law and solved for , the temperature given is 400 Kelvin. When 400 Kelvin is put in the conversion equation, the degrees farenheit given is 260.6 degrees.
Example Question #114 : Chemistry
The Ideal Gas Law is as follows:
is pressure as measured in Pascals, is volume as measured in cubic meters, is the number of moles of the gas, is the gas constant known as 8.314 Joules per mole times Kelvin, and is the temperature measured in Kelvin.
A class of students began studying the Ideal Gas Law and how the Pressure and the Volume relate to one another. They took 20 moles of a sample gas and kept the room at a temperature of 300 Kelvin. They then used different sized containers of the gas to limit and expand the volume. At each different volume, they measure the pressure of the gas on its container. The table they made from their results is seen in table 1.
Temperature in Kelvin |
Pressure Measured in Pascals |
|
|
200 Kelvin |
16, 628 Pascals |
400 Kelvin |
33, 256 Pascals |
600 Kelvin |
49, 884 Pascals |
800 Kelvin |
66, 512 Pascals |
TABLE 1
FIGURE 1
The graph the students made based on the data is seen in Figure 1.
Pressure is created by the movement of the gas molecules pushing against a container. 0 Kelvin is known as absolute 0, the temperature at which all molecule movement theoretically stops.
If the equation that converts temperature Kelvin to temperature in degrees Fahrenheit is
what is the pressure of the sample gas at the freezing point of water, which is 32 degrees Fahrenheit?
To find the temperature Kelvin to which 32 degrees Fahrenheit correlates, the equation would look like this and one must solve for :
. Then, this temperature must be put into the Ideal Gas Law and solved for pressure:
Example Question #801 : Act Science
Current high levels of fossil fuel use, including coal-burning power plants and gasoline-powered automobiles, have helped contribute to the high concentrations of sulfur trioxide, SO3, found in the atmosphere. When sulfur trioxide and water interact, they can undergo the following chemical reaction to produce sulfuric acid, which is the main contributor to acid rain worldwide:
Acid rain showers are particularly common near coal-burning power plants and large cities. These showers are responsible for significant economic damage to sidewalks, roads, and buildings. Scientists interested in studying the effects of acid rain often use basic substances like calcium carbonate, the main component of limestone buildings, and expose them to varying volumes of acid rain to determine what volume of acid rain is necessary to begin to erode a building. A sample graph of one scientist’s experiment is replicated below:
Measuring acid and base levels is commonly done with a scale called pH, which uses the concentration of hydrogen ions to determine the acidity. Hydrogen ions are in a balance with hydroxide ions to give a scale with a range from 0 to 14. Values equal to or between 0 and 6.9 represent the acidic range where hydrogen ions predominate and values equal to or ranging from 7.1 and 14 represent the basic range where hydroxide ions predominate. Thus, the more hydrogen ions present, the more acidic the solution.
Scientists can tell when a titration (pH) experiment passes a certain pH using compounds called indicators. Indicators are usually colorless at pH levels below that of their specified color change. A table of indicators used by the above scientists and the pH at which they change colors is presented below.
Solutions A, B, and C each contain a different number of hydroxide ions. Solution A has an intermediate number of hydroxide ion, while solution B has the most, and solution C the fewest. Place the solutions in order of increasing number of hydrogen ions.
C < B < A
B < A < C
A < B < C
C < A < B
B < A < C
This question asks us to determine the relative order of three solutions with respect to their hydrogen ion number. The passage, particurarly the paragraph provided below the graph, tells us that when the hydrogen ion number is high, the hydroxide number is low. Thus a high number of hydroxide ions would give a low number of hydrogen ions. We can use this information to place the three solutions in order.