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Chapter 13. Gases

- The air resistance needed to keep the skydivers from descending too quickly is provided by the atmosphere.

- We are immersed in a solution.
- Oxygen, O2 and N2 are some of the gases in the earth's atmosphere.
- The atmosphere supports life and acts as a waste receptacle for the exhaust gases that accompany industrial processes.
- Smog and acid rain can be caused by the chemical reactions of waste gases in the atmosphere.
- The production of electricity and transportation are the main sources of pollution.
- Unburned fragments of the fuel used as fuel are produced along with CO, CO2, NO, and NO2 in vehicles.
- NO2 and SO2 are produced in the exhaust gases from power plants.
- The photochemical smog that afflicts most large cities can be created by absorbing light.
- The SO2 in the air reacts with oxygen to produce SO3 gas, which combines with water in the air to produce droplets of sulfuric acid, a major component of acid rain.

- The gases in the atmosphere keep the earth warm and shield us from harmful radiation from the sun.
- An increase in atmospheric carbon dioxide, a product of the burning of fossil fuels, is causing a dangerous warming of the earth.

- The properties of gases will be looked at in this chapter.
- The first thing we will see is how gas properties lead to different types of laws.
- We will build a model to explain why gases behave the way they do.
- The model will show how the behavior of individual particles of a gas leads to the observed properties of the gas itself.

- An example of the scientific method in action is provided by the study of gases.
- Natural laws can be accounted for by models.

- The Breitling Orbiter 3, shown over the Swiss Alps, recently completed a nonstop trip around the world.

- To learn how barometers work.
- To understand the different units of pressure.

- A gas uniformly fills any container, is easily compressed, and mixes with any other gas.
- A gas exerts pressure on its surroundings.
- When you blow up a balloon, the air inside pushes against the elastic sides of the balloon and keeps it firm.

- The gases form the atmosphere.
- The experiment shown in Figure 13.1 shows the pressure exerted by the air.
- A small volume of water is placed in a metal can, and the water is boiled, which fills the can with steam.
- The can crumples because of the atmospheric pressure.
- The water in the can condenses to a small amount of liquid water when it's cooled after being sealed.
- The water in the can did not come close to filling the can when it was a gas.
- The H2O molecule that used to be a gas is now collected in a much smaller volume of liquid, and there are very few left to exert pressure outside and counteract the air pressure.
- The pressure in the atmosphere causes the can to be smashed.

- Evangelista Torricelli, who was a student of Galileo, was the inventor of the barometer, a device that measures atmospheric pressure.
- Torricelli's barometer is made using a glass tube filled with liquid mercury and a dish of mercury, as shown in Figure 13.2.

- An air pump was invented by a German physicist.
- In a famous demonstration for the King of Prussia in 1683, Guericke placed two hemispheres together, pumped the air out of the sphere through a valve, and showed that teams of horses could not pull the hemispheres apart.
- After opening the air valve, Guericke was able to separate the hemispheres by hand.

- When a glass tube is filled with mercury and inverted in a dish of mercury at sea level, the mercury flows out of the tube until a column approximately 760mm high remains.
- The column of mercury in the tube is balanced by the pressure of the atmosphere.

- The weight of the air pulls the mass of the air toward the center of the earth.
- The height of the column of Hg supported by the atmosphere at sea level is not always 760mm.
- The atmospheric pressure is going to decrease when a "low" is approaching.
- This condition can occur in conjunction with a storm.

- The atmospheric pressure varies with altitude.
- At sea level there is more air pushing down on the earth's surface.

- Medical science is always looking for new ways to diagnose diseases.
- One method that is very promising is the analysis of a person's breath.
- This is not a new idea.
- Hippocrates suggested a link between breath odor and disease as early as 400 b.c.
- Doctors are now aware that patients with organ failure have a distinctive smell in their breaths.
- Scientists are able to identify compounds in a patient's breath that are related to a disease.

- Breath analysis is hard.
- A person's breath contains a lot of substances.
- Many of these substances are found in the person's diet, medication, and ambient air.
- Progress is being made despite the difficulties.
- The University of California has a Professor of Mechanical and Aerospace Engineering named Cristina Davis.
- Professor Davis is working on a portable asthma monitor that will measure the level of inflammation in a patient's breath.
- The Cleveland Clinic is testing a breath sensor that can diagnose lung cancer with 80% accuracy.
- The tests are using a more sensitive device.
- Breath tests are being studied for other types of cancer, such as colon cancer and breast cancer.

- Breath analysis developments are on the horizon.

- The units for pressure are usually based on the height of the mercury column that the gas pressure can support.
- The terms torr andmm Hg are used by different people.

- Mercury has a high density and is used to measure pressure.
- The column of water required to measure a given pressure is 13.6 times higher than the mercury column used for the same purpose.

- A manometer is used to measure the pressure of a gas in a container.
- The pressure of the gas is equal to the difference in mercury levels.

- The SI unit for pressure is the pascal, which is equal to one newton per square meter.

- 100,000 or 105 pascals is the atmosphere.
- The pascal is small and we will use it a lot in this book.
- The pound per square inch is a unit of pressure used in the engineering sciences to measure tire pressure.

- Sometimes we have to convert from one unit of pressure to another.
- conversion factors are used to do this.
- The process is shown in an example.

- The tire's pressure is measured by the air in it.

- The tire's air pressure is checked.

- We want to convert from units of pounds per square inch to units of atmospheres, torr, and pascals.

- The units have equivalence statements.

- The units on the answers are required.

- What is the air pressure in the atmosphere?
- Hg.

There are problems of 13.11 and 13.12

- The law relates the pressure and volume of a gas.
- To do calculations related to this law.

- The first careful experiments on gases were performed by the Irish scientist.
- Using a J-shaped tube closed at one end, he studied the relationship between the pressure of the trapped gas and its volume.
- Table 13.1 contains representative values from the experiments.
- The units given for the volume and pressure are the ones used.
- The metric system was not used at this time.

- The J-tube is similar to the one used by Boyle.
- Adding or withdrawing mercury can change the pressure on the trapped gas.

- The product can have three significant figures because both of the numbers that are multiplied together have three significant figures.

- The volume of trapped gas decreases as the pressure increases.
- If you compare the data from experiments 1 and 4 you can see that the volume of gas is halved when the pressure is doubled.
- Experiments 2 and 5 and 3 and 6 have the same relationship.

- To see the relationship between the volume of a gas and its pressure, we can look at the product of the values of the two properties.
- The product is shown in the last column.

- The same behavior is shown by other similar measurements.

- The amount of gas must not be changed.
- The temperature has to be constant.

- If we make a graph, we can see the relationships between the two properties.
- The plot shows that V decreases as P increases.
- When this type of relationship exists, we say that volume and pressure are related in some way.
- The gas samples are shown in Figure 13.6.

- The containers have the same number of molecules.

- If we know the volume of a gas at a given pressure, we can predict the new volume if the pressure is not changed.

- This is another way to write the law.
- The final volume can be solved by dividing the equation into two parts.

- The new gas volume can be calculated by taking the original volume and dividing it by the ratio of the final pressure to the original volume.

- The compound CCl2F2 has been replaced by other compounds that do not cause the breakdown of the protective ozone in the upper atmosphere.
- Consider a sample of CCl2F2 at a pressure of 56 torr.

- We want to know if the volume will increase or decrease when the pressure is changed.

- We know the initial and final pressures.
- The amount of gas and temperature is constant.

- The volume must decrease because the pressure is increased from 56 torr to 150 torr.
- The ratio P1/P2 is less than 1 because P1 is less than P2.
- The volume decreases if V2 is a fraction of V. We expect the volume to decrease because of the increased pressure.
- The pressure increased and the volume decreased.

- A sample of neon that will be used in a neon sign has a volume of 1.51 L.

- Problems 13.21 and 13.22 can be seen.

- We want to know the new pressure of the fuel-air mixture.

- We know the initial pressure and volumes.
- The amount of gas and temperature is constant.

- We expect the pressure to increase because the volume is decreasing.
- The pressure increased by about a factor of 10 and the volume decreased by about a factor of 10.

- To learn more about absolute zero.
- To learn about the law relating the volume and temperature of a sample of gas at constant pressure and moles.

- Scientists continued to study the properties of gases in the century after Boyle's findings.
- Jacques Charles was the first person to fill a balloon with hydrogen gas and made the first solo balloon flight.
- When the temperature goes up, the volume goes up.
- A straight line is given by a plot of the volume of gas at constant pressure versus its temperature.
- This type of relationship is called linear, and is shown in Figure 13.

- When it is hot, the air in a balloon expands.
- This means that some of the air escapes from the balloon, lowering the air density inside and making the balloon float.

- The plots are spread out by the different number of moles in each sample of gas.

- The solid lines are based on the actual temperature and volume of the gases listed.
- We can't determine any experimental points below this temperature because the gases liquefy as we cool them.
- Something very interesting happens when we extend each straight line.
- 0 K has never been reached, despite the temperatures being obtained in the laboratory.

- When the volumes of gases are plotted against the temperature on the Kelvin scale rather than the Celsius scale, the plots shown in Figure 13.8 result.
- The volume of each gas is proportional to the temperature in kelvins and can be zero when the temperature is 0 K. An example can be used to illustrate this statement.
- At 300 K, we have 1 L of gas.
- When we double the temperature of this gas to 600 K, the volume also doubles to 2 L. Look at the lines for various gases in Figure 13.8 to verify this type of behavior.

- The Plots of V vs. T are the same as in Figure 13.

- Charles's law holds for a sample of gas at constant pressure.

- The second form of this equation states that the ratio of V to T must be constant.
- The volume of the gas triples when we triple the temperature in kelvins.

- Charles's law can be written in terms of V1 and T1 and V2 and T2.

- We will show the use of this equation in two examples.

- Charles's law states that the volume of a gas is related to its temperature in kelvins and number of moles.

- A 2.0-L sample of air is collected and cooled.
- The pressure is held constant.

- We want to know if the volume will increase or decrease when the temperature is changed.

- We know the initial and final temperatures.
- The amount of gas and pressure is constant.

- We expect the volume to decrease because the temperature decreases.
- We would expect the volume to decrease slightly because the temperature decreased slightly.

- We want to know if the volume will increase or decrease when the temperature is changed.

- We know the initial and final temperatures.
- The amount of gas and pressure is constant.

- Charles's law states that the volume of a sample of gas is proportional to the temperature.

- The temperatures are usually given in Celsius degrees.
- Charles's law requires the temperature to be in kelvins.
- Adding 273 to each temperature is required to convert.

- We expect the volume to increase because the temperature increases.

- There is a steaming volcanic vent at Mount Baker in Washington.

- Problems 13.29 and 13.30 can be seen.

- We can adjust the volume of a gas for a temperature change by taking the final temperature and dividing it by the initial temperature.
- Do you know if your answer makes sense?
- The volume must increase when the temperature increases.

- Gas volume was once used as a way to measure temperature.

- We want to know the new temperature of a gas when the volume has decreased.

- We know the initial temperature and initial volumes.
- The amount of gas and pressure is constant.

- We divide both sides by T2.

- We divide both sides by T1.

- We can do the calculation with T2 isolated on one side of the equation.

- To convert from units of K to units of Cdeg, we have to subtract 273 from the temperature.

- We expect the temperature to be lower because the volume is smaller.

- To understand the law relating the volume and the number of moles of a sample of gas at constant temperature and pressure.

- When the number of moles of gas is doubled, the volume doubles.
- If temperature and pressure remain constant, the volume of a gas is proportional to the number of moles.

- The volume doubles when the number of moles is increased from 1 to 2.
- The volume is also tripled when the number of moles is tripled.
- The temperature and pressure are the same.

- As long as the temperature and pressure remain constant, the ratio of V to n is constant.

- The number of moles of gas is proportional to the volume of the gas.
- Avogadro's lawEqual volumes of gases at the same temperature and pressure have the same number of particles.

- We will show you how to use this equation.

- The volume of ozone formed from 0.50 mole of O2 is what we want to determine.

- The initial number of moles of oxygen and the volume of oxygen are known.
- The pressure and temperature are the same.

- The number of moles of ozone formed is determined by the balanced equation.

- We need to compare the moles of gas originally present to the moles of gas present after the reaction.
- We know that 0.50 mole of O2 is present.
- The balanced equation is needed to find out how many moles of O3 will be present after the reaction.

- The mole ratio from the balanced equation is used to calculate the moles of O3.

The volume should decrease because fewer molecules are present in the gas after O2 is converted to O3

- Consider two samples of nitrogen gas.

- There are problems in 13.41, 13.42, 13.43 and 13.44.

- To use the ideal gas law in calculations.

- The behavior of gases is described by three laws.

- A constant number of moles of gas is what Constant n means.

- R always has the value of 0.08206 L atm/K mol when the pressure is expressed in atmospheres.

- The ideal gas law involves the characteristics of a gas: its pressure, volume, number of moles, and temperature.
- The condition of the gas can be determined from the knowledge of any three of these properties.

- The ideal gas law is based on the experimental measurement of the properties of gases.
- A gas that obeys the equation behaves well.
- A hypothetical gas that obeys the ideal gas law is defined by this equation.
- At high temperature or low pressure, a real gas approaches ideal behavior.
- When working problems involving gases, you should assume ideal gas behavior.

- A variety of problems can be solved with the ideal gas law.

- We want to know the number of moles of hydrogen gas present under certain conditions.

- We know how much hydrogen gas there is.

- The temperature needs to be changed to the scale.

- The ideal gas law can be used to calculate the number of moles of gas present.

- A weather balloon has 1.10x105 moles and a volume of 2.70x106 L.

- You can see the problems of 13.53, 13.54, 13.55, 13.56, 13.57, and 13.58.

- We want to know how much CO2 is in the air given the number of moles, pressure, and temperature.

- The number of moles, pressure, and temperature of carbon dioxide are known.

- The ideal gas law can be used to calculate the volume, but we must first convert pressure to atmospheres and temperature.

- The ideal gas law is divided into two sides by P.

- The sample of CO2 has a volume of 12.5 L.

- Lung cancer can be caused by a radioactive gas in the soil.
- It can pose a hazard to humans by entering houses, and there is concern about this problem in many areas.
- A sample of radon gas has a volume of 21.0 L. Cdeg.

- You can see the problems of 13.53, 13.54, 13.55, 13.56, 13.57, and 13.58.

- R has units of L atm/K mol.
- The ideal gas law requires us to express the volume in units of liters, the temperature in kelvins, and the pressure in atmospheres.
- We need to convert the data in other units to the appropriate ones.

- The ideal gas law can be used to calculate the changes that will occur when the conditions of the gas are changed.

- The ideal gas law can be used to calculate the final pressure.

- The ideal gas law equation can be used to determine the pressure of ammonia gas.

- The initial number of moles, pressure, volume, and temperature of ammonia are known.
- We are aware of the new volume.

- There is a sample of ammonia gas in which the conditions are changed.

- Both n and T remain the same.
- We could use Boyle's law to solve for P2 The ideal gas law will be used to solve this problem in order to introduce the idea that one equation can be used to solve almost any gas problem.
- In using the ideal gas law to describe a change in conditions for a gas, we always solve the equation in such a way that the variables that change are on one side of the equals sign and the constant terms are on the other side.
- The ideal gas equation in the conventional form should be rearranged so that the terms that change are moved to one side and the terms that don't change are moved to the other side.
- The temperature and number of moles remain constant in this case, as does the pressure and volume change.

- We can write P1V1 and P2V2 if R, T, and n remain the same.

- The calculation indicates that the pressure should increase because the volume was decreased at a constant temperature and number of moles.

- There are problems 13.61 and 13.62.

- We obtained Boyle's law from the ideal gas equation.
- The ideal gas equation can be used to solve gas law problems.

- The ideal gas law is being practiced.
- The key idea is to rearrange the equation so that the quantities that change are moved to one side of the equation and the quantities that remain constant are moved to the other.

- The ideal gas law equation can be used to determine the volume of diborane gas.

- The pressure, volume, and temperature of the diborane gas are known.
- We are aware of the new temperature and pressure.

- The value of n is not given.
- We know that n is constant because no diborane gas is added or taken away.
- In this experiment, n is constant and P, V, and T change.

- If we divide both sides by P2 and then divide them by T2 we can solve V2.

- It's convenient to think of the ratios of the initial temperature and pressure and the final temperature and pressure.

- There are problems 13.61 and 13.62.

- The popping is related to gases.
- Charles's law states that if the pressure is held constant, the volume of gas must increase as the temperature increases.

- The pressure of a gas is proportional to the temperature when n, R, and V are held constant.
- The pressure of the trapped gas increases as the temperature increases.
- This is what happens when popcorn is heated.
- The heat causes increasing pressure inside the kernels.
- The pressure gets so great that the kernels break open, allowing the starch inside to expand to 40 times its original size.

- The pericarp is where popcorn's "popability" is found, according to William da Silva, a Biologist at the University of Campinas in Brazil.
- The pressure jump that pops the popcorn is caused by the heat transfer from the pericarp of popcorn to regular corn.
- The pericarp of popcorn is thicker and stronger than regular corn, so it can hold more pressure, leading to a more powerful pop when the time is right.

- When the amount of gas is constant, it holds.
- It's not necessary to remember this equation because you can always use the ideal gas equation.

- To understand the relationship between the partial and total pressures of a gas mixture.

- A mixture of components is found in many important gases.
- Air is an example.
- helium and oxygen are used by scuba divers who are going deeper than 150 feet.
- The high pressures experienced by the diver under several hundred feet of water causes the nitrogen present in the blood to be dissolved in large quantities.
- When the diver returns too quickly to the surface, nitrogen bubbles out of the blood, just as soda bubbles when it's opened, and the diver gets "the bends", a very painful and potentially fatal condition.
- The problem is not caused by helium gas being in blood.

- Studies show that each component behaves in its own way.
- Oxygen exerts the same pressure in a 1.0-L vessel whether it is alone or in the presence of nitrogen or helium.

- John was one of the first scientists to study gases.
- For a mixture of gases in a container, the total pressure is the sum of the partial pressures of the gases present.
- The partial pressure is the pressure that the gas would exert if it were alone in the container.

- The partial pressures are P1, P2 and P3 and they are responsible for only part of the total pressure.

- The total pressure is the sum of the partial pressures of the gases.

- For ideal gases, the total number of moles of particles is more important than the individual gas particles.
- This idea is shown in a figure.

- The three samples show the same pressure because they have the same amount of gas.
- The nature of the mixture is unimportant.

- The volume of the gas particle is not important.
- The forces of the particles are unimportant.

- The pressure of the gas depends on the nature of the individual particles.
- An argon atom is larger than a helium atom.

- The behavior of an ideal gas seems to be unaffected by the forces among gas particles.
- The model that we will construct to explain ideal gas behavior will be influenced by these observations.

- Oxygen and helium are used in the air tanks of underwater divers.

- We want to know the total pressure of the tank.

- The initial volume, pressure, and temperature of both gases are known.
- The final volume of the tank is known.
- The temperature is the same.

- The temperature in the tank is 25Cdeg and it has a volume of 5.0 L. The ideal gas law can be used to calculate the partial pressure of each gas.

- When diving to depths greater than 150 feet, divers use a mixture of oxygen and helium in their breathing tanks.

- The partial pressures are the sum of the total pressures.

- The pressure of each gas increased.
- It makes sense that the initial temperatures and pressures of helium and oxygen were the same, but the initial volume of helium was much greater than that of oxygen.

- There are Problems 13.67, 13.68, and 13.69.

- A mixture of gases occurs when a gas is collected.
- The collection of oxygen gas that is produced by the decomposition of solid potassium chlorate is shown in Figure 13.12 The gas is collected by filling the bottle with water.
- The gas in the bottle is a mixture of water and oxygen.
- The total pressure is the sum of the partial pressure of the gas being collected and the partial pressure of the water vapor.
- The vapor pressure of water is called the partial pressure.
- Vapor pressure of water increases with temperature because water is more likely to escape from hot water than from cold water.
- The values of vapor pressure are shown in Table 13.2.

- The number of moles of O2 present and the partial pressure of oxygen collected by water displacement are what we want to determine.

- We know how much gas is collected by water displacement.
- We know the pressure of water.

- We can subtract 21 torr from the equation to solve it.

- The ideal gas law is the number of moles of O2.

- The gaseous mixture has a volume of 0.500 L and a total pressure of 0.950 atm.
- 24 torr is due to the water vapor.

- You can see the problems.

- To understand the relationship between models and laws.

- We have seen how mathematical equations can be used to express the relationships between gases' properties in this chapter.
- The ideal gas equation relates all the important gas properties.
- Gases don't obey the ideal gas equation under certain conditions.
- The ideal gas equation predicts the properties of gases at high pressures and low temperatures.
- Almost all gases agree with the ideal gas equation when the pressure is lowered or the temperature increases.
- An ideal gas is a hypothetical substance.
- Real gases approach the behavior expected for an ideal gas at low pressures and high temperatures.

- We want to understand why a gas behaves the way it does.
- Let's review the scientific method first.
- Many experiments have shown that a law is a generalization of behavior.
- Laws allow us to predict the behavior of similar systems.
- A chemist can assume that a new compound will obey the ideal gas equation if they prepare it.

- Laws don't tell us why nature behaves the way it does.
- Scientists attempt to answer the question by constructing theories.
- The models in chemistry are speculations about how individual atoms or Molecules cause the behavior of macroscopic systems so that we can observe them.

- A model that predicts the results of future experiments is considered successful.
- A model can never be proved to be true.
- Any model is an approximation and is destined to be modified in part.
- The models range from simple to complex to account for observed behavior.
- The models used in this text fit most experimental results.

- To understand the basic postulates of the theory.

- The model that attempts to explain the behavior of an ideal gas is a simple one that assumes that an ideal gas is composed of tiny particles.
- There are speculations about the behavior of the individual particles in a gas.

- The volume of the individual particles can be assumed to be zero, because they are so small.
- The particles collide with the walls of the container.
- The gas exerts pressure when the walls are hit.
- The particles aren't assumed to attract or repel each other.
- The gas particles have a direct correlation to the temperature of the gas.

- The energy associated with the motion of a particle is referred to in postulate 5.
- The mass of the particle and the speed of the particle are given by the equation.
- Postulate 5 means that if a gas is heated to higher temperatures, the average speed of the particles increases.

- In the next section, we will see that the postulates listed here explain ideal gas behavior--behavior shown by real gases at high temperatures and/or low pressures.

- You've learned about the postulates of the theory.

- To understand temperature.
- To learn how the gas laws are explained.

- The qualitative relationships between theKM theory and the properties of gases will be discussed in this section.
- Without going into the mathematical details, we will show how the kinetic molecular theory explains some of the observed properties of gases.

- In Chapter 2, we introduced temperature as a measure.
- As the temperature of an object increases, it feels hotter to the touch.
- The idea that temperature is an index of motion was introduced in Chapter 10.
- The concept can be further developed with the help of the kinetic molecular theory.
- According to postulate 5 of the KM theory, the temperature of a gas reflects how quickly individual gas particles are moving.
- At high temperatures the particles move very fast and hit the walls of the container frequently, whereas at low temperatures the particles' motions are more sluggish and they collide with the walls of the container less often.
- The motions of the gas particles are measured by temperature.
- The average kinetic energy of the gas particles is directly proportional to the temperature of the gas.

- To see how the meaning of temperature helps to explain gas behavior, take a picture of a gas in a container.
- The particles move faster when the gas is heated to a higher temperature.
- As the particles move faster, the impacts become more powerful.
- As the temperature increases, the gas pressure should increase.

- If the volume is not changed, a sample of gas in a container shows an increase in pressure.

- Take a picture of the gas in a container.
- The external pressure Pext is balanced by the gas pressure Pgas.
- The particles move faster as the temperature increases.
- The piston moves up until Pgas is greater than Pext.
- The KM model predicts that the volume of the gas will increase as we raise its temperature.
- Charles's law states that this agrees with experimental observations.

- The pressure of a gas can be predicted by using the KM theory.

- The particles don't have to travel so far between the walls when we decrease the gas's volume.
- The increase in pressure would be suggested by this.
- The model is in agreement with experimental observations of gas behavior.

- In this section we have seen that the predictions of the theory fit the behavior of gases.
- It is a successful model because of this.

- Modern automobiles have air bags that have led to a reduction in injuries as a result of crashes.
- Air bags are stored in the steering wheel and dashboard of all cars, and many autos now have additional air bags that protect the occupant's knees, head, and shoulders.
- Air bags are now included in the seat belts.
- All cars now have "smart" air bags that deploy with an inflation force that is proportional to the seat occupant's weight, because deployment of an air bag can severely injury a child.

- Air is not involved in the inflation process so the term "air bag" is not really a good one.
- An air bag inflates quickly due to the production of N2 gas.

- The air bags must be triggered very quickly.
- Consider a car hitting a bridge.
- The control module gets a message from the internal accelerometer that a collision is possible.
- The air-bag deployment is decided by the microprocessor after it analyzes the measured deceleration from several sensors.
- Within 8 to 40 ms of the initial impact, all this happens.

- An air bag has to provide the right effect in order for it to vent as it is being filled.
- Even in the middle of a collision event, the maximum pressure in the bag is 5 pounds per square inch.
- Air bags are used to save lives rather than reverse them.

- To understand the volume of an ideal gas.
- To understand the definition of STP.
- To use the ideal gas equation.

- In this chapter, we have seen how useful the ideal gas equation is.
- If we know the pressure, volume, and temperature, we can calculate the number of moles present.
- It is possible to do calculations for reactions involving gases.
- This process will be shown in example 13.15

- We want to know how much oxygen gas was collected.

- We know the pressure and temperature of oxygen.
- We know the mass.

- The number of moles is what we need.

- This is a similar problem to the one we considered in Chapter 9.
- The number of grams is not the same as the volume of a gaseous product.
- The ideal gas law gives us the relationship between moles and volume.

- The moles of KClO3 can be found using the molar mass of KClO3.

- The mole ratio of O2 to KClO3 is derived from the balanced equation.

- 3.13 L of O2 will be produced.

- There are problems of 13.86, 13.88, 13.89, 13.90, and 13.89.

- It is useful to define the volume occupied by 1 mole of a gas under certain conditions.

- The volume of 22.4 L is equal to 22.42 liters at a standard temperature and pressure of an ideal gas.

- Under these conditions, the properties of gases can be given.
- The ideal gas has a molar volume of 22.4 L. The ideal gas at STP is 1 mole.

- A sample of nitrogen gas has a volume of 1.75 L.

- We want to know how many moles of nitrogen gas there are.

- The nitrogen gas has a volume of 1.75 L.

- A mole of ideal gas occupies a volume of 22.4 L.

- The ideal gas equation can be used to solve this problem, but we can use the molar volume of an ideal gas at STP.
- A 1.75-L sample of N2 at STP contains less than 1 mole because it has a volume of 22.4 L.

- Ammonia can be used as a source of nitrogen for plants.
- The most convenient way to do this problem is to use the molar volume at STP.

- There are Problems 132.95, 13.96, 13.97, and 13.98.

- Standard conditions and molar volume are useful for carrying out calculations on reactions involving gases.

- We want to know the volume of carbon dioxide produced.

- The temperature and pressure of carbon dioxide gas are known.
- The mass of CaCO3 is known.

- We need a certain number of moles of carbon dioxide gas.

- The number of moles of CaCO3 is calculated using the molar mass of CaCO3.

- 1.52 moles of CO2 will be formed by each mole of CaCO3.

- The molar volume of an ideal gas can be used to convert the moles of CO2 to volume.

- 34.1 L of CO2 is produced by the decomposition of 152 g of CaCO3.

- The final step involves calculating the volume of gas from the number of moles.
- We were able to use the molar volume of the gas because the conditions were specified.
- The ideal gas law can be used to compute the volume if the conditions of a problem are different from STP.

- A hypothetical gas that obeys the ideal gas law is expressed in the equation.

- The units for pressure are millimetres Hg, atmosphere, and pascal.
- The pascal is the SI unit.
- The volume of gas at a constant temperature varies according to its pressure.
- Charles's law states that the volume of an ideal gas at constant pressure varies with its temperature.
- Avogadro's law states for an ideal gas at constant temperature and pressure, the volume depends on the number of moles of gas.
- The ideal gas law describes the relationship between P, V, n, and T. The combined gas law can be obtained from the ideal gas law, which states that the total pressure of a mixture of gases is equal to the sum of the individual.
- The relationship of P, V, T, and n for an ideal gas is explained by a model based on the properties of individual gas components.
- A law is a summary of observations.
- Theory is an attempt to explain observed behavior.
- The average energy of the gas particles is reflected by the temperature of the ideal gas.
- As the gas temperature increases, the pressure of the gas increases.
- When a gas is heated to a higher temperature, the particles of the gas speed up.
- The volume of 1 mole of an ideal gas is 22.4 L.

- Group of students in class will be asked these questions.
- For introducing a topic in class, these questions work well.

- The Student Solutions Guide has full solutions for the questions and problems below.

- Solids are rigid and have definite shapes and volumes.
- Liquids take the shape of their containers and are less rigid than solid objects.
- Gases have no fixed volume or shape, they take the volume and shape of their container, and are affected more by changes in their pressure and temperature than are liquids.
- An experiment can be used to demonstrate the pressure exerted by the atmosphere.
- Write an explanation of the experiment to a friend who has not yet taken any science courses to help him understand the concept of atmospheric pressure.
- A mercury barometer consists of a tube filled with mercury that is inverted over a surface of mercury that is open to the atmosphere.
- The column of mercury in the tube is supported by the height of the atmosphere.

- Two gases that don't react with each other are put in the same container.

- Which experimental unit is derived from the device used to measure atmospheric pressure?
- The unit "mm Hg" is derived from the barometer because in a traditional mercury barometer, we measure the height of the mercury column in millimeters.

- The Student Solutions Guide has full solutions for the questions and problems below.

- If you're talking to a friend who has not yet taken any science courses, tell her how you would explain the law to her.
- Adding mercury increases the pressure on the gas sample, causing the volume of the gas to decrease.

- The volume of a sample of ideal gas is related to the temperature of the gas.
- P1V1 is a mathematical expression that summarizes the law.

- The new volume of the gas sample should be calculated after the pressure change is made.

- The Student Solutions Guide has full solutions for the questions and problems below.

- Explain the concept of absolute zero to a friend of yours who has not yet taken any science courses.
- Charles's law states that an ideal gas decreases in volume for every degree its temperature is lowered.

- The volume of ideal gas is determined by its temperature at constant pressure.
- There is a mathematical expression that summarizes Charles's law.

- The new volume of the neon sample will be calculated after the change is made.
- A sample of argon is cooled from 450 K to 250 K at constant pressure.
- A sample of gas has a volume of 127 mL in a boiling water bath.
- Cdeg.

- The Student Solutions Guide has full solutions for the questions and problems below.

- The volume of a sample of ideal gas is determined by the number of moles of gas present.
- A mathematical expression that summarizes Avogadro's law is V.

If 1.04 g of chlorine gas occupies a volume of 872 mL at a particular temperature and pressure, what volume will 2.08 g of chlorine gas occupy under the same conditions?

- The Student Solutions Guide has full solutions for the questions and problems below.

- Real gases behave best at high temperatures and low pressures.
- The ideal gas law can be derived from the gas law.
- The ideal gas law can be derived from Charles's gas law.
- Consider a sample of gas at a fixed pressure.
- The volume of the gas sample is V1.
- For this set of conditions, the ideal gas equation would be given.
- The ideal gas equation would be given by the new conditions.
- If we make a ratio of these two expressions for the ideal gas equation for this gas sample, we get V1V2 or T1T.

- There is a sample of neon gas in a container.
- Suppose the temperature is raised to 50 degrees.
- The pressure of the flask will be higher than the pressure of the argon.
- 1.29 g of argon gas is confined to a volume of 2.41 L. The ideal gas law can be used to estimate the pressure inside popcorn.
- Measure the mass of popcorn before and after popping to determine the mass of water released.
- The mass of water lost on popping is assumed to be the difference in mass.
- We can calculate the pressure inside the kernels just before they pop by taking a total volume of 2.0 mL and a mass of 0.250 g of water lost from them.

- The Student Solutions Guide has full solutions for the questions and problems below.

- The Student Solutions Guide has full solutions for the questions and problems below.

- A theory that has been successful in the past can be successful in the future.
- Theories that have been successful in the past may not be as successful in the future.

- The Student Solutions Guide has full solutions for the questions and problems below.

- The gas's observed pressure is caused byCollisions of the molecule in a sample of gas with the walls of the container.
- The average of the molecule in the sample of gas is called the temperature.
- The theory of gases suggests that gas particles do not exert attractive or repulsive forces on each other.

- The Student Solutions Guide has full solutions for the questions and problems below.

- If the temperature of a sample of gas is increased, the average kinetic energy of the particles of gas increases.
- The speeds of the particles increase.
- The particles will hit the walls of the container more frequently if they have a higher speed.

- The Student Solutions Guide has full solutions for the questions and problems below.

- These conditions are easy to reproduce and attain.

- The temperature must be expressed in terms of the temperature scale when calculating gas samples.

- A widely used weather instrument called a barometer can be built from a thin tube of glass that is sealed at one end.
- There is a small pool of mercury in the inverted tube.
- Initially, the mercury inside the tube drops but then it goes back up.
- The height of the column of mercury is a measure of pressure in millimetres Hg.
- Which of the following is the best explanation of how this barometer works?
- Air pressure outside the tube counterbalances the weight of the mercury inside the tube.

- At constant temperature, the lighter the gas molecule, the faster the average velocity of the gas molecule.
- Draw what each diagram will look like after the stopcock between the two flasks is opened.
- In terms of the original pressure, solve for the final pressure in each case.
- The gas particles will distribute uniformly throughout both flasks if the temperature is constant.

- The total pressure exerted by a mixture of gases in the same container is the pressure that those gases would exert if they were alone in the container.

- 25.2 L of helium is contained in a tank.
- The temperature is lower in the upper atmosphere than at sea level.
- As they rise, weather balloons expand.
- Three gases are produced when ammonium carbonate is heated.

- You have an ideal gas in a balloon.
- The pressure in the balloon should double and the temperature should be halved if the volume is decreased by more than half the original volume.

- Predict what will happen when 10.0 g of oxygen gas is added to the container if the 2.50-L container is rigid.
- The container is rigid and cannot expand, so the volume is constant.
- The missing quantity is calculated for each set of pressure/volume data.
- If the temperature remains constant, what will be the new pressure if the volume increases to 0.794 L?
- You can change one of the conditions of the gas in a container fitted with a piston, and explain why each change would work.
- If the temperature goes up, the gas particles have more energy and will hit the piston with more force.
- The volume will increase if the pressure inside the container is the same as outside the container.
- Adding moles of gas to the container will cause gas particles to hit the walls of the container more frequently.
- The volume will increase if the pressure inside the container is the same as outside the container.
- The pressure inside becomes greater than the pressure outside.
- When the pressure inside the container is the same as outside the container, the gas particles inside will push the piston up.
- One of the tanks is going to be filled with hydrogen and the other with helium.
- A sample of neon gas exerts a pressure of 2.0 atm at a certain temperature and volume.
- The heat is turned off and the can is sealed after it is boiled with a small amount of water.
- The can does not explode or crumple because the pressure inside the can and the pressure outside the can remain "balanced" or equalized.
- The can crumples because the gaseous water does not have as much energy as the liquid.
- Liquid water does not take up as much space as gas in the can.
- There are less moles of gas in the can colliding with the walls of the container.
- There are two gas cylinders.
- The gas cylinder A has a volume of 48.2 L and contains N2(g) at 8.35 atm.
- The gas cylinder B has a volume of 22.0 L. When the two cylinders are connected with a valve of negligible volume and the gases are mixed, the pressure in each cylinder increases.
- Make sure to address the variables P, V, n, and T.n and T are constant before and after the valve is connected to show the relationship between pressure and volume.
- The inverse relationship is shown when the volume expands into two cylinders and the pressure decreases.
- The first step in the process is the reaction of solid calcium carbide with liquid water.
- Second, the acetylene gas produced is then ignited with a match, causing the combustion reaction of acetylene with oxygen gas to produce gaseous carbon dioxide and gaseous water.
- If the connecting tube has negligible volume, draw what each diagram will look like after the stopcock between the two flasks is opened.
- The final pressure of the original pressures of helium and neon is assumed to be constant.
- It is assumed that the temperature is constant.
- The chemistry of air bags is discussed in the "Chemistry in Focus" segment.
- Use the balanced chemical equation in the segment to determine the mass of azide needed to inflate an air bag.
- Breath analysis is used to diagnose diseases in the "Chemistry in Focus" segment.
- 4% of what we exhale is carbon dioxide, and the volume of the average human breath is 500 mL.
- Determine the mass of carbon dioxide exhaled by a human.

- The same type of assistance a student would get from an instructor can be found in these multiconcept problems.

- After some argon has been used, the pressure is 2.00 MPa.
- The balloon has a pressure of 605 torr and a temperature of 15 degrees.
- There is a reaction between the xenon and fluorine.

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