Solutions and States of Matter - AP Chemistry
Card 0 of 2320
A gas is behaving ideally
2 mols of the gas would have what volume at STP?
A gas is behaving ideally
2 mols of the gas would have what volume at STP?
use PV = nRT
V = nRT / P ; must covert T into K
V = (2)(0.0821)(273)/ 1
= 44.8 L
use PV = nRT
V = nRT / P ; must covert T into K
V = (2)(0.0821)(273)/ 1
= 44.8 L
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Which of the following situations would most likely cause gases to deviate from ideal behavior?
Which of the following situations would most likely cause gases to deviate from ideal behavior?
At high pressure and low temperature two things are happening that will cause gases to deviate from ideal behavior. At low temperature the individual gas molecules are moving slower. As the pressure is increased the individual molecules are being pushed closer to one another. Thus, when the gas molecules are closer together and moving at reduced speeds they are more likely to interact with one another. Ideal gas behavior is dependent upon an absence of intermolecular interaction between the gas molecules. Therefore, the increased likelihood of intermolecular interactions between the gas molecules at increased pressure and decreased temperature is likely to cause gases to deviate from ideal behavior.
At high pressure and low temperature two things are happening that will cause gases to deviate from ideal behavior. At low temperature the individual gas molecules are moving slower. As the pressure is increased the individual molecules are being pushed closer to one another. Thus, when the gas molecules are closer together and moving at reduced speeds they are more likely to interact with one another. Ideal gas behavior is dependent upon an absence of intermolecular interaction between the gas molecules. Therefore, the increased likelihood of intermolecular interactions between the gas molecules at increased pressure and decreased temperature is likely to cause gases to deviate from ideal behavior.
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Two balloons are filled with gas at STP. One is filled with hydrogen gas, the other with neon gas. The Volume of the balloon filled with hydrogen gas is 22.4 L, the balloon filled with neon is 44.8 L.
There are more atoms in which balloon?
Two balloons are filled with gas at STP. One is filled with hydrogen gas, the other with neon gas. The Volume of the balloon filled with hydrogen gas is 22.4 L, the balloon filled with neon is 44.8 L.
There are more atoms in which balloon?
Hydrogen gas is a diatomic gas, so the molecules that are filling the balloon exist as H2. Neon since it is a noble gas exists as a monoatomic gas, so the molecules that are filling the neon balloon exist as Ne. The volumes given allow us to calculate the amount of each gas in moles. At STP one mole of gas occupies 22.4 L, so there is one mole of hydrogen gas and there are two moles of neon gas. One mole of hydrogen gas indicates that there are actually two moles of hydrogen atoms in the balloon. Two moles of neon gas indicates that there are two moles of neon gas present in the balloon because neon exists as a monoatomic gas. Thus there are two moles of atoms in each balloon.
Hydrogen gas is a diatomic gas, so the molecules that are filling the balloon exist as H2. Neon since it is a noble gas exists as a monoatomic gas, so the molecules that are filling the neon balloon exist as Ne. The volumes given allow us to calculate the amount of each gas in moles. At STP one mole of gas occupies 22.4 L, so there is one mole of hydrogen gas and there are two moles of neon gas. One mole of hydrogen gas indicates that there are actually two moles of hydrogen atoms in the balloon. Two moles of neon gas indicates that there are two moles of neon gas present in the balloon because neon exists as a monoatomic gas. Thus there are two moles of atoms in each balloon.
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Which of the following is a characterization of an ideal gas?
I. Low concentration
II. High Pressure
III. Elastic Collisions
Which of the following is a characterization of an ideal gas?
I. Low concentration
II. High Pressure
III. Elastic Collisions
An ideal gas is most likely low concentration of identical molecules and low pressure. The molecules move randomly and collisions are completely elastic.
An ideal gas is most likely low concentration of identical molecules and low pressure. The molecules move randomly and collisions are completely elastic.
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Oil and vinegar is a very popular salad dressing. It also is commonly used for dipping bread. The main component of the oil phase is olive oil, while the main part of the vinegar portion is aqueous acetic acid.
When oil and vinegar salad dressing is allowed to stand at room temperature, two distinct phases are observed. The main explanation for this phenomenon is the difference in
of the two phases.
Oil and vinegar is a very popular salad dressing. It also is commonly used for dipping bread. The main component of the oil phase is olive oil, while the main part of the vinegar portion is aqueous acetic acid.
When oil and vinegar salad dressing is allowed to stand at room temperature, two distinct phases are observed. The main explanation for this phenomenon is the difference in of the two phases.
Olive oil, like most oils, is non-polar, while aqueous acetic acid is very polar. These two phases do not mix because of their different solvent polarities.
Olive oil, like most oils, is non-polar, while aqueous acetic acid is very polar. These two phases do not mix because of their different solvent polarities.
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Hydrogen gas is being stored in a container. The pressure of the gas is suddenly doubled. What could NOT be an explanation for this sudden change?
Hydrogen gas is being stored in a container. The pressure of the gas is suddenly doubled. What could NOT be an explanation for this sudden change?
When dealing with gas problems that have multiple factors but very little data is given, it is a good idea to use the ideal gas law to compare factors.
The ideal gas law is written as PV = nRT
This allows us to see how factors could affect the pressure in the container. By lowering volume, we would see that pressure increased. If more gas was allowed into the container (increasing n), the pressure would increase as well. If we lower the temperature (lower T), then pressure should decrease as well. As a result, pressure rising due to a drop in temperature does not make sense in this question.
When dealing with gas problems that have multiple factors but very little data is given, it is a good idea to use the ideal gas law to compare factors.
The ideal gas law is written as PV = nRT
This allows us to see how factors could affect the pressure in the container. By lowering volume, we would see that pressure increased. If more gas was allowed into the container (increasing n), the pressure would increase as well. If we lower the temperature (lower T), then pressure should decrease as well. As a result, pressure rising due to a drop in temperature does not make sense in this question.
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A 3 liter container contains hydrogen gas. Assuming standard temperature and pressure (STP) and ideal conditions, how many moles of hydrogen gas are present in the container?
A 3 liter container contains hydrogen gas. Assuming standard temperature and pressure (STP) and ideal conditions, how many moles of hydrogen gas are present in the container?
At STP, one mole of an ideal gas occupies 22.4L. You should know this value for the exam.
Another approach would use the ideal gas law: 
. Since we know that the container is at STP, we know that the container has a temperature of 273.15K and has a pressure of 1atm.
Adding the other known variables, the equation becomes
Solving for n, we find that there is 0.13 moles of hydrogen gas in the container.
At STP, one mole of an ideal gas occupies 22.4L. You should know this value for the exam.
Another approach would use the ideal gas law:
Adding the other known variables, the equation becomes
Solving for n, we find that there is 0.13 moles of hydrogen gas in the container.
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In reality, the pressure of a gas is slightly less than the pressure predicted for an ideal gas. This is because
.
In reality, the pressure of a gas is slightly less than the pressure predicted for an ideal gas. This is because .
Ideal gas pressure only takes the repulsive forces between gas molecules into consideration. The truth is, gas molecules can also exhibit attractive forces with one another (London dispersion forces). This attractive force pulls the molecules inward and slows their velocity before striking the wall of the container. As a result, real gases exert slightly less pressure compared to the ideal pressure.
Ideal gas pressure only takes the repulsive forces between gas molecules into consideration. The truth is, gas molecules can also exhibit attractive forces with one another (London dispersion forces). This attractive force pulls the molecules inward and slows their velocity before striking the wall of the container. As a result, real gases exert slightly less pressure compared to the ideal pressure.
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In reality, the volume of a gas is slightly larger than the ideal volume. This is because
.
In reality, the volume of a gas is slightly larger than the ideal volume. This is because .
One of the key charactersitics of an ideal gas is that gas molecules have no volume. This is obviously not the case, and the volume of the molecules must be added to the ideal volume. As a result, the real volume is slightly larger than the ideal volume.
One of the key charactersitics of an ideal gas is that gas molecules have no volume. This is obviously not the case, and the volume of the molecules must be added to the ideal volume. As a result, the real volume is slightly larger than the ideal volume.
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If you create a perfect vacuum and place a glass of water into the vacuum at room temperature, what will happen to the water?
If you create a perfect vacuum and place a glass of water into the vacuum at room temperature, what will happen to the water?
Boiling occurs when the vapor pressure exceeds the air pressure. There is no air pressure in a vacuum, so water at any temperature will boil in a vacuum.
Boiling occurs when the vapor pressure exceeds the air pressure. There is no air pressure in a vacuum, so water at any temperature will boil in a vacuum.
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Which of the following conditions would cause a gas to act the most like an ideal gas?
Which of the following conditions would cause a gas to act the most like an ideal gas?
An ideal gas acts as if there are no interactions between the gaseous molecules during their rapid movements. At high temperature and low pressure the particles of the gas will not interact very much, as they will have high energy and will move around very fast. The faster the movement, the less time and contact the particles have with one another. The slower the particles are moving, the more they are starting to act like a liquid, and less like an ideal gas. High pressure will condense the particles, while low pressure will allow them to move freely. High temperature will add energy to speed the particles, while low temperature will slow them down.
An ideal gas acts as if there are no interactions between the gaseous molecules during their rapid movements. At high temperature and low pressure the particles of the gas will not interact very much, as they will have high energy and will move around very fast. The faster the movement, the less time and contact the particles have with one another. The slower the particles are moving, the more they are starting to act like a liquid, and less like an ideal gas. High pressure will condense the particles, while low pressure will allow them to move freely. High temperature will add energy to speed the particles, while low temperature will slow them down.
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You place some balloons in your car, and leave them to sit as the car is heated by the sun. What effect would this have on the gases inside the helium balloons?
Assume the balloons are fully elastic.
You place some balloons in your car, and leave them to sit as the car is heated by the sun. What effect would this have on the gases inside the helium balloons?
Assume the balloons are fully elastic.
We can predict the result of the heating by using the ideal gas law:
We know that 
, which is a constant, will never change. We also know that 
, the number of moles of helium inside the balloons, will stay the same since no gas is added or removed from the sealed balloons.
The variables in this case are pressure, volume, and temperature. We know that the temperature will increase because the sun is heating up the car. This leaves us with pressure and volume. Pressure will not increase because the balloons are elastic; as the gas expands, the balloons expand as well without increasing the pressure. In this scenario, only the volume will increase.
We can predict the result of the heating by using the ideal gas law:
We know that
The variables in this case are pressure, volume, and temperature. We know that the temperature will increase because the sun is heating up the car. This leaves us with pressure and volume. Pressure will not increase because the balloons are elastic; as the gas expands, the balloons expand as well without increasing the pressure. In this scenario, only the volume will increase.
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Boiling points at standard temperature and pressure:
Methanol- 
Toluene- 
Water- 
Methylene chloride- 
Dimethylsulfoxide- 
Of the five compounds given, which will have the highest vapor pressure at standard temperature and pressure?
Boiling points at standard temperature and pressure:
Methanol-
Toluene-
Water-
Methylene chloride-
Dimethylsulfoxide-
Of the five compounds given, which will have the highest vapor pressure at standard temperature and pressure?
A liquid will boil when its vapor pressure increases to match the pressure of its environment. By this logic, a liquid with a higher vapor pressure will be closer to boiling. Liquids with low boiling points thus have greater vapor pressures.
Of the given compounds, methylene chloride has the lowest boiling point, meaning it will also have the highest vapor pressure.
A liquid will boil when its vapor pressure increases to match the pressure of its environment. By this logic, a liquid with a higher vapor pressure will be closer to boiling. Liquids with low boiling points thus have greater vapor pressures.
Of the given compounds, methylene chloride has the lowest boiling point, meaning it will also have the highest vapor pressure.
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Which of the following conditions would result in the deviation of a gas from ideality?
Which of the following conditions would result in the deviation of a gas from ideality?
Under high pressure, the volume of the gas molecules would no longer be negligible—one of the assumptions for an ideal gas. In addition, at low temperature, the molecules would have less kinetic energy, and intermolecular forces could take affect—another assumption of an ideal gas is that there are no intermolecular attractions or repulsions.
At low pressure and high temperature, gases behave more like gases and liquids are more likely to boil (convert to gas). At high pressure and low temperature, gases behave less ideally and can condense (convert to liquid).
Under high pressure, the volume of the gas molecules would no longer be negligible—one of the assumptions for an ideal gas. In addition, at low temperature, the molecules would have less kinetic energy, and intermolecular forces could take affect—another assumption of an ideal gas is that there are no intermolecular attractions or repulsions.
At low pressure and high temperature, gases behave more like gases and liquids are more likely to boil (convert to gas). At high pressure and low temperature, gases behave less ideally and can condense (convert to liquid).
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When does a gas behave most like an ideal gas?
When does a gas behave most like an ideal gas?
The ideal gas law assumes the gas particles are non-interacting and small relative to the size of their container. At high temperatures the gas molecules are moving fast enough to shorten the time scale for any interactions. At high volumes, the molecular size becomes small relative to the size of the container, and the low interactions mean the molecules act more independently.
The ideal gas law assumes the gas particles are non-interacting and small relative to the size of their container. At high temperatures the gas molecules are moving fast enough to shorten the time scale for any interactions. At high volumes, the molecular size becomes small relative to the size of the container, and the low interactions mean the molecules act more independently.
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Under which conditions would you expect Ar to deviate the most from ideal behavior?
Under which conditions would you expect Ar to deviate the most from ideal behavior?
The ideal gas law assumes the gas particles are non-interacting and small relative to the size of their container. At 200K (lowest temperature in the list, and the highest pressure). This gives Ar the most time to interact due to molecular speeds and the high pressure implies the molecular size is not insignificant relative to the container.
The ideal gas law assumes the gas particles are non-interacting and small relative to the size of their container. At 200K (lowest temperature in the list, and the highest pressure). This gives Ar the most time to interact due to molecular speeds and the high pressure implies the molecular size is not insignificant relative to the container.
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Would you expect a polar or non polar gas to deviate most from ideal gas behavior?
Would you expect a polar or non polar gas to deviate most from ideal gas behavior?
Polar gases would have increased interactions due to their dipoles that would lead to deviations from ideal gas behavior.
Polar gases would have increased interactions due to their dipoles that would lead to deviations from ideal gas behavior.
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Which of the following would behave most like an ideal gas?
Which of the following would behave most like an ideal gas?
is the smallest molecule in the list, and therefore the least size effects.
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Why do gases deviate from ideal behavior as the temperature is decreased?
Why do gases deviate from ideal behavior as the temperature is decreased?
The ideal gas law assumes the gas particles are non-interacting and small relative to the size of their container. As the temperature is decreased the gas molecules are moving slower and allow for a greater degree of interaction.
The ideal gas law assumes the gas particles are non-interacting and small relative to the size of their container. As the temperature is decreased the gas molecules are moving slower and allow for a greater degree of interaction.
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How much faster/slower the rate of effusion for oxygen gas compared to hydrogen gas?
How much faster/slower the rate of effusion for oxygen gas compared to hydrogen gas?
Rate of effusion:
and 
must be used because they exist as bimolecular molecules. The correct answer is that Oxygen gas will effuse 4 times slower than hydrogen gas.
Rate of effusion:
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