Module 3 Intro

Chemistry 20 © 2008 Alberta Education

Chemistry 20 © 2008 Alberta Education

Chemistry 20 © 2008 Alberta Education

Chemistry 20 © 2008 Alberta Education

Chemistry 20 © 2008 Alberta Education

Chemistry 20 © 2008 Alberta Education

Chemistry 20 © 2008 Alberta Education

Chemistry 20 © 2008 Alberta Education

Chemistry 20 © 2008 Alberta Education

Module 3—Behaviour of Gases

Lesson 2—Kelvin Temperature, Charles’ Law, and the Combined Gas Law

 

Get Focused

 

On a cold winter day in Alberta, temperatures may be around –30°C. On a hot summer day in Alberta, the temperature may be around 30°C. Is it easier to breathe in cold weather or hot weather? You probably find that it is more difficult to breathe when it is cold outside. This isn’t purely temperature dependent, however. Other factors, such as humidity, also affect breathing.

 

Try This

 

Step 1: Inflate a balloon.

 

Step 2: Measure the size of the balloon.

 

Step 3: Place the balloon into a freezer (typically around –18°C), and leave it there for ten minutes.

 

Step 4: Remove the balloon from the freezer and quickly determine its size.

 

Does the balloon get bigger or smaller when it is cooled?

 

In Lesson 1 you learned that the pressure of a gas is the result of the collisions of the gas molecules against the surfaces of its container. Do you recall how temperature affects the motion of particles? How would this explain the change in the size of the balloon upon cooling and heating?

 

The investigation you completed identifies an important relationship between temperature and volume of a gas. This relationship was first described by Jacques Charles—a French chemist, physicist, and aeronaut. In 1783, Charles made the first hot-air balloon using hydrogen gas and ascended to a height of nearly 3 km. Charles’ work with hot-air balloons set the stage for his discovery of the relationship between temperature and volume.

 

In this lesson you will investigate this relationship, as well as consider the relationship of pressure, volume, and temperature for a fixed amount of gas.

 

Essential Questions

• What is the Kelvin temperature scale, and why is it used?
  
  
• What are the relationships among pressure, volume, amount, and temperature for a fixed amount of gas?

  Module 3: Lesson 2 Assignment

Save a copy of the Module 3: Lesson 2 Assignment to your course folder. Later in the lesson you will receive more information about how to complete this assignment and when to submit it to your teacher.

 

You must decide what to do with the questions that are not marked by the teacher.

 

Remember that these questions provide you with the practice and feedback that you need to successfully complete this course. You should respond to all the questions and place those answers in your course folder.

 

Chemistry 20 © 2008 Alberta Education

Module 3—Behaviour of Gases

Explore

 

You may have observed a container rupture as a result of the expansion of the trapped gas inside. This event may occur if the gas is heated, for instance by the sun on a hot day or by exposure to another heat source.

 

Read

 

The kinetic molecular theory states that particles increase their rate of motion with increased temperature. How does this theory relate to the pressure and volume of a confined gas?

 

Read “The Relationship Between Temperature and Volume” on pages 152 to 153 and “Temperature Measurement Technologies” on pages 155 and 156 in your textbook. You will learn more about the absolute temperature scale and how it is related to the motion of particles. You will also find out why precise measurement is necessary for scientific investigation of gases.

 

Self-Check

 

SC 1. Complete the following table.

 

Temperature (°C)	Temperature (K)
–38
	358
104
	413
173

 

 

Read

 

In the Try This activity you completed earlier, you noticed that when the balloon cooled, it was reduced in size, or the volume the gas inside occupied, was less.

 

What would happen if you cooled or heated the gas inside the balloon and continued to measure its volume? Would you be able to observe a pattern?

 

Read “Charles’ Law” on pages 154 and 155 in your textbook. Carefully work through “COMMUNICATION example 3” and the “Learning Tip” in the margin on page 155.

 

Important: Remember that temperatures used in calculations must be in kelvin, not degrees Celsius.

 

Self-Check

 

SC 2. A balloon containing 1.25 L of helium is heated and increases in temperature from 21°C to 87°C. If kept at constant pressure, what is the final volume of the helium in the balloon?

SC 3. A balloon has a volume of 55.0 L at 22.0°C. To what temperature does the balloon need to be raised to have a volume of 80.0 L at the same pressure?

SC 4. A gas has a volume of 3.30 L and a temperature of 25.0°C. The temperature of the gas is increased, and the new volume is 4.20 L. If the pressure is held constant, what is the new temperature of the gas?

 

SC 5. A gas is in a perfectly airtight metal cylinder with a movable top to allow for the expansion/compression of the gas. Charles’ law states that the ratio of volume to temperature for a gas is a constant, according to this formula:

 

 

Design an experiment to determine the value of k for the gas.

 

 

Try This

 

For additional practice, try the following questions in your textbook:

• questions 11, 12, and 13 on page 154
• questions 14(a), 15, 16, and 17 on page 156
  

You can find the answers to these questions on page 783 in Appendix A of your textbook.

 

Module 3: Lesson 2 Assignment

 

You will use the following lab to complete part of your Lesson 2 Assignment. Retrieve your saved copy of the Lesson 2 Assignment now.

 

Chemistry 20 © 2008 Alberta Education

Module 3—Behaviour of Gases

Lab: Charles’ Law

 

The following lab activity will enable you to complete a virtual investigation of Charles’ law. Be sure you read through the Background, Procedure, and Assignment before beginning the lab.

 

Record the data collected from the experiment in Part 1 of the assignment, and complete the questions under Procedure 1 and Procedure 2. Save copies of the graphs you drew for the data. Save a copy of your work in your course folder.

 

Read

 

The combined gas law describes a relationship among pressure, volume, and temperature consistent with Boyle’s law and Charles’ law. Read “The Combined Gas Law” on page 156 to 158 in your textbook. Carefully work through “SAMPLE problem 4.1” and “COMMUNICATION example 4” on pages 157 and 158.

 

Self-Check

 

SC 6. A gas has a volume of 32 L, a temperature of 22°C, and a pressure of 92 kPa. If the temperature is decreased to 19°C and the pressure is increased to 98 kPa, what is the new volume of the gas?

SC 7. The combined gas law is very useful, since it is possible to obtain both Boyle’s law and Charles’ law from this one formula.

1. Explain how Boyle’s law may be obtained from the combined gas law.
2. Explain how Charles’ law may be obtained from the combined gas law.

 

Chemistry 20 © 2008 Alberta Education

Module 3—Behaviour of Gases

Reflect and Connect

 

High-Altitude Balloons

 

Throughout this module you will be asked to consider technologies that apply the use of one or more of the gas laws. For your combined unit and module assessment, you will prepare a response on a technology that applies one or more of the gas laws. To prepare your response, consider the following description of high-altitude balloons. Refer to the Unit Assessment document for more information.

 

The Breitling Orbiter 3 was the first hot-air balloon to complete a non-stop trip around the world. High-altitude ballooning involves a great deal of knowledge about gases and their behaviour. Use the Internet to research this topic by combining the search terms breitling, balloon, and design to learn more about the design of this balloon. Use your knowledge of the gas laws to explain how these design considerations are consistent with the relationships described in the gas laws you have studied.

 

Save a copy of your explanation in your course folder. You may wish to use this information when completing the unit assessment. For more information on the unit assessment, refer to the Unit Assessment document.

 

Module 3: Lesson 2 Assignment

 

Retrieve the Module 3: Lesson 2 Assignment you saved to your course folder earlier in this lesson. Complete Part 2 of Lesson 2 Assignment, and save a copy of your work in your course folder.

 

Once you have completed all of the questions, submit your work to your teacher.

 

Chemistry 20 © 2008 Alberta Education

Module 3—Behaviour of Gases

Lesson Summary

 

In this lesson you investigated the following questions:

• What is the Kelvin temperature scale, and why is it used?
  
  
• What are the relationships among amount, pressure, volume, and temperature for a fixed amount of gas?

In this lesson you explored the Kelvin temperature scale and the basis of this scale—absolute zero. You discovered that when using Charles’ law and the combined gas law, Kelvin temperatures are needed. As such, you converted between degrees Celsius and kelvin.

 

You then discovered Charles’ law, which states as the temperature of a gas increases, the volume increases proportionally, provided that the pressure and chemical amount of gas remain constant.

 

You performed calculations and completed a virtual lab based on Charles’ law.

 

Finally, you combined Charles’ law with Boyle’s law to form the combined gas law and performed various calculations based on the resulting formula.

 

Chemistry 20 © 2008 Alberta Education

Module 3—Behaviour of Gases

Lesson 3—The Law of Combining Volumes and Avogadro’s Theory

 

Get Focused

 

High-altitude ballooning creates many unique situations that must be considered. One aspect is the quantity of available oxygen. Oxygen is necessary for the crew to survive, and at high altitudes in the atmosphere, oxygen is less plentiful. You may recall that hot air within the balloon is necessary for lift. The air inside the balloon is heated by a combustion reaction. How is this possible in the upper atmosphere with limited oxygen?

 

You may notice the large compressed gas cylinders along the side of the Breitling Orbiter 3, the first hot-air balloon to circle Earth without stopping. The gases in the Breitling orbiter balloon were heated using a combustion reaction involving propane and oxygen. When planning the flight, the balloonists needed to know how many canisters of each gas, propane and oxygen, to carry. How would knowledge of gas laws assist their efforts?

 

Essential Question

• Is it possible to predict the quantity of a gaseous substance involved in a chemical reaction?

Assessment

 

There is no Module 3: Lesson 3 Assignment.

 

You must decide what to do with the questions that are not marked by the teacher.

 

Remember that these questions provide you with the practice and feedback that you need to successfully complete this course. You should respond to all the questions and place those answers in your course folder.

 

Chemistry 20 © 2008 Alberta Education

Module 3—Behaviour of Gases

Explore

 

Read

 

In Lessons 1 and 2 of this module you referred to the kinetic molecular theory of matter to help you visualize the behaviour of gas particles explained by the gas laws you have studied.  This theory can be used to develop a model that explains the physical behaviour of gases. In the gas phase, all pure substances show remarkably similar physical behaviour.

 

In your experiments conducted thus far, the relationships among pressure, volume, and temperature by Boyle’s law and Charles’ law were verified with all the gases tested. What is true for nitrogen is true for oxygen, hydrogen, and any other gas. The behaviour of gases is independent of the type of gas present. The fact that different gases resemble each other so closely in their physical behaviour has some interesting results.

 

Read pages 163 and 164 in your textbook to review a summary of the application of concepts of the kinetic molecular theory to what you have learned thus far in this module.

 

Self-Check

 

SC 1.    Complete “Practice” question 1 (a) through (e) on page 164 of your textbook.

 

 

Chemistry 20 © 2008 Alberta Education

Module 3—Behaviour of Gases

Read

 

The kinetic molecular theory, Boyle’s law, and Charles’ law consider individual or mixtures of unreactive gases. What happens when gaseous substances mix and react? Is there evidence that shows how gaseous substances react with one another?

 

The Law of Combining Volumes

 

The law of combining volumes was observed by Joseph Gay-Lussac in 1809. This law states that when temperature and pressure are kept constant, the volumes of gaseous reactants and products in chemical reactions are always in simple ratios of whole numbers. An example is the formation of water, which always requires a ratio of 2 (hydrogen) : 1 (oxygen).

 

Word Equation	hydrogen	+	oxygen	→	water
Volume	2.0 L		1.0 L		2.0 L

 

Volumes of gases were measured because that was empirically possible. But how does a measure of the volumes of gases relate to the number of particles present? Is there a relationship between volume and number of particles in a system?

 

Avogadro’s Theory

 

In 1811, Amedeo Avogadro explained Gay-Lussac’s observations. Avogadro noticed the relationship between the ratio of gas volume and the coefficient ratio of a balanced equation.

 

The coefficient ratio of hydrogen gas to oxygen gas is also 2:1—the same as the gas volume ratio. Finally, there is Avogadro's Theory, which states that equal volumes of gases at the same temperature and pressure contain equal numbers of molecules. An example is the formation of water.

Word Equation	hydrogen	+	oxygen	→	water
Balanced Equation	2 H2(g)	+	O2(g)	→	2 H2O(g)
Ratio	2		1		2
Volume	2.0 L		1.0 L		2.0 L

 

 

 

 

 

Since equal volumes contain equal numbers of gas molecules, a chemical equation in which all the substances are in the gas phase can be read two ways: as moles of each substance involved, or as litres of each substance involved.

It is important to note that the ratio describes the comparative quantity of each substance in the balanced equation, not the exact quantity. In other words, it does not always have to be 2.0 L of hydrogen, 1.0 L of oxygen, and 2.0 L of water. You must, however, always have twice as much hydrogen as oxygen during the formation of water.

 

Example

 

Complete the following table.

 

Word Equation	hydrogen	+	oxygen	→	water
Balanced Equation	2 H2(g)	+	O2(g)	→	2 H2O(g)
Ratio	2		1		2
Volume			225 mL

 

According to the ratio, there is twice as much hydrogen as oxygen. Therefore, the volume of hydrogen must be 2 × 225 mL = 450 mL. Similarly, there is twice as much water as oxygen, which equates to 2 × 225 mL = 450 mL.

 

For additional clarification of this important law, read “Explaining the Law of Combining Volumes” on pages 164 to 166 in your textbook. Carefully work through “SAMPLE problem 4.2” and the “COMMUNICATION example” in this section.

 

You may wish to listen to the audio explanation of “SAMPLE problem 4.2.”

 

 

Chemistry 20 © 2008 Alberta Education

Module 3—Behaviour of Gases

Self-Check

 

SC 2. Complete the following table.

 

Word Equation	hydrogen	+	chlorine	→	hydrogen chloride
Balanced Equation	H2(g)	+		→	2 HCl(g)
Ratio	1				2
Volume			1.1 L

 

SC 3.

 

The Breitling Orbiter 3 uses the combustion of propane and oxygen to heat gases in the two chambers of the high-altitude balloon. Complete the following table to investigate the proportion by which propane and oxygen are used in a combustion reaction.

 

Word Equation	propane	+	oxygen	→	carbon dioxide	+	water vapour
Balanced Equation		+	5 O2(g)	→	3 CO2(g)	+	4 H2O(g)
Ratio			5		3		4
Volume							80 mL

 

SC 4. Use the law of combining volumes to find the volume of oxygen required for the complete combustion of 83.0 mL of propane. Assume the pressure and temperature are held constant.

 

SC 5. Butane gas is combusted to produce carbon dioxide and water vapour. If 2.4 mol of butane reacts, how many moles of water vapour will be produced?

 

SC 6. Complete question 5(a) on page 168 of your textbook.

 

 

Chemistry 20 © 2008 Alberta Education

Module 3—Behaviour of Gases

Reflect on the Big Picture

 

High-Altitude Balloons

Throughout this module you will be asked to consider technologies that apply the use of one or more of the gas laws. For your combined unit and module assessment, you will prepare a response on a technology that applies gas laws. To prepare your response, consider the following information relating to the gases necessary for high-altitude flights. Refer to the Unit Assessment document for more information.

 

Large compressed gas cylinders containing oxygen, and others containing propane, are situated along the side of the Breitling Orbiter 3. A combustion reaction involving these two gases is used to heat the gases within the balloon. When planning the flight, the balloonists needed to know how many canisters of each gas, propane and oxygen, to carry.

 

Use your knowledge of the gas laws to explain how the law of combining volumes or Avogadro’s theory is incorporated in the design of the system to heat the gases in a high-altitude balloon.

 

Save a copy of your explanation in your course folder. You may wish to use this explanation when completing the unit assessment. For more information on the unit assessment, refer to the Unit Assessment section.

 

Assessment

 

There is no Module 3: Lesson 3 Assignment.

 

In this lesson you continued to consider technologies that apply the use of one or more of the gas laws. Later you will be given instructions about submitting the combined unit/module assessment to your teacher.

 

Chemistry 20 © 2008 Alberta Education

Module 3—Behaviour of Gases

Lesson Summary

 

In this lesson you explored the following question:

• Is it possible to predict the quantity of a gaseous substance involved in a chemical reaction?

Joseph Gay-Lussac developed the theory that gases react in distinct proportions. When gases are at similar temperatures and pressures, the proportions are identical to the volumes of each gas involved in the reaction.

 

This theory of combining volumes of gases was further supported by Avogadro’s law that extends an understanding of this relationship to the moles of each substance involved. This law states that when temperature and pressure are kept constant, equal volumes of gases at the same temperature and pressure contain equal numbers of molecules.

 

With this information, you can analyze and predict the quantities of gases involved in chemical reactions. In Unit D you will further your understanding of quantitative relationships in chemical reactions.

 

Chemistry 20 © 2008 Alberta Education

Module 3—Behaviour of Gases

Lesson 4—Molar Volume and the Ideal Gas Law

 

Get Focused

 

A flat tire can be a real problem when cycling. Not only does it take time to change the tire, but getting the inflation correct can be tricky. Riding on an underinflated tire decreases efficiency. It may also decrease your ability to steer around hazards in your path. Pinching the tire is one way to check the inflation of a tire, but more often a pressure gauge is used to get an accurate reading. Inflating a tire to the appropriate pressure involves adding air, but what quantity of gas is necessary for proper inflation?

 

In Lesson 3 you began to investigate the relationship between the chemical quantity of a gas (moles) and one of its measurable properties (volume). In Lessons 1 and 2 you investigated relationships between volume and pressure and between volume and temperature.

 

There is also the empirical relationship you may have already observed—adding more gas (increasing moles) will increase the pressure exerted by gas.

 

How can all of these relationships be combined to better explain and predict the relationship between quantity of gas and its measurable properties?

 

Essential Questions

• What is molar volume?

• What is the difference between a real gas and an ideal gas?

• What relationship exists between pressure, volume, temperature, and moles of gas?

Module 3: Lesson 4 Assignment

Save a copy of the Module 3: Lesson 4 Assignment to your course folder. You will receive more information about how to complete this assignment later in this lesson.

 

You must decide what to do with the questions that are not marked by the teacher.

 

Remember that these questions provide you with the practice and feedback that you need to successfully complete this course. You should respond to all the questions and place those answers in your course folder.

 

Chemistry 20 © 2008 Alberta Education

Module 3—Behaviour of Gases

Explore

 

Molar Volume of Gases

 

Avogadro’s theory states that equal volumes of any gas, measured at constant temperature and pressure, contain equal numbers of molecules. But how many molecules are there?

 

From your previous learning in science you know that chemical quantities are expressed as moles. A mole is defined as 6.02 × 1023 atoms, molecules, or particles. Therefore when you indicate that a mole of propane combusts, you are also saying that 6.02 × 1023 molecules of propane combust. To make measuring a quantity of a gas easier, we often use volumes—so what volume does one mole of propane, or any other gas, occupy?

It should not surprise you that the molar volume for all gases is dependent upon the temperature and pressure of the gas. Therefore, there are two common temperature/pressure sets:

Set	Conditions
standard temperature and pressure (STP)	0°C and 101.325 kPa
standard ambient temperature and pressure (SATP)	25°C and 100 kPa

 

At these conditions a mole of any gas has the following volumes:

 

STP   22.4 L/mol.

 

 

This means that one mole of gas at STP constitutes about 11 two-litre pop bottles!

 

SATP 24.8L/mol

 

If the conditions are changed to SATP, a higher temperature, and a slightly lower pressure, the volume occupied by the same number of particles of gas is 24.8 L/mol.

 

 

This means that one mole of gas at SATP constitutes over 12 two-litre pop bottles!

 

Volumes are used when dealing with gases because measuring the mass of a gas is just too hard! Knowing the molar volume allows you to calculate the number of moles of a gas or the volume of gas according to this formula:

 

 

Example 1

 

How many moles of oxygen are available for a combustion reaction in a volume of 5.6 L at STP?

 

 

What volume is occupied by 0.024 mol of carbon dioxide gas at SATP?

 

 

Chemistry 20 © 2008 Alberta Education

Module 3—Behaviour of Gases

Read

 

For clarification of molar volume of gases, read the information on pages 169 and 170 in your textbook. You will also find out about the calculations involved in converting a volume of gas at one of the standard conditions into moles of gas.

 

Self-Check

 

SC 1. Hydrogen gas can be used in weather balloons because of its low density. The volume occupied by 4.50 mol of hydrogen at SATP is

1. 109 L
2. 111 L
3. 112 L
4. 113 L
   

SC 2. Hydrogen gas can be used in weather balloons because of its low density. The volume occupied by 4.50 mol of hydrogen at STP is

1. 99.1 L
2. 101 L
3. 102 L
4. 112 L
   

SC 3. Nitrogen gas is an important gas in artificial breathing apparatus. The number of moles of nitrogen gas in 100 L of pure nitrogen at STP is

1. 4.46 mol
2. 4.03 mol
3. 3.81 mol
4. 2.76 mol
   

SC 4. Nitrogen gas is an important gas in artificial breathing apparatus. The number of moles of nitrogen gas in 100 L of pure nitrogen at SATP is

1. 4.46 mol
2. 4.03 mol
3. 3.81 mol
4. 2.76 mol

 

In some situations the mass of the gas is able to be measured or is communicated. From your study of gases in this unit, you will understand why a value for mass is often converted into a volume for that gas. What calculation is necessary for this conversion?

 

Molar Mass

 

In previous science courses you learned how to calculate moles of a substance from mass. Molar mass is the value used to convert mass to moles. Follow the example below to review this conversion. 

Example 2

 

Carbon dioxide is a greenhouse gas. Convert 1.5 kg of carbon dioxide into moles.

 

Step 1: Write the chemical formula for carbon dioxide.

 

CO2

 

Step 2: Determine the molar mass of carbon dioxide. The molar mass of each element is found on the periodic table.

 

 

Step 3: Determine the number of moles.

 

You can combine the two formulas for number of moles, n, to calculate the volume of gas that is available from a known mass of a substance. This is done as follows:

 

 

Example 3

 

What volume does 1.5 kg of carbon dioxide gas occupy at SATP?

 

Self-Check

 

SC 5. How many grams of oxygen gas are present in a 5.00-L container at STP?

 

SC 6. At SATP, what volume will 84.7 g of argon gas occupy?

 

 

Chemistry 20 © 2008 Alberta Education

Module 3—Behaviour of Gases

Read

 

Real vs. Ideal Gases

 

In Lesson 1 you completed a lab investigating the relationship between pressure and volume of two gases. Did you observe any difference in the way the gases behaved? If you look back on your data and graphs, you will notice that the data collected for the two gases are almost identical.

 

This lab demonstrated that as long as temperature was constant, and the gases were compressed to similar volumes, they produced the same pressure. As you learned in this module, the pressure exerted by a gas is a direct result of its motion. When gases produce equal pressures when all other conditions are similar, it means that the degree of motion of the two gases is the same.

 

In Unit A you learned about intermolecular forces and how attractions between atoms and molecules in a system can influence boiling point. You might ask whether the difference in intermolecular forces between these two gases tested would alter their behaviour and cause a difference in the observed pressure of each gas.

 

Clearly the data from your experiment shows this is not the case, and that the gases are behaving independent of these kinds of forces under the conditions of the experiment. When gases do not appear to be influenced by forces between them, along with other characteristics, they exhibit ideal behaviour.

 

Read “The Ideal Gas Law” on pages 172 through 174 in your textbook. You will find out what other conditions make the behaviour of a gas “ideal.” In this section you will also learn about the development of the ideal gas law, a relationship among all the variables you have studied in this unit: pressure, volume, temperature, and moles of gas.

 

Carefully work through “SAMPLE problem 4.4,” the “COMMUNICATION example” on page 174, and the following examples.

 

Example 4

 

How many grams of oxygen gas are there in a 60.0-L tank at 25.0°C when the pressure in the tank is 12.2 MPa (MPa = megapascals)?

 

First, determine the number of moles using the ideal gas law.

 

Now, determine the number of grams of oxygen.

 

The mass of O2(g) is 9.45 × 103 g or 9.45 kg.

 

Example 5

 

Experiments show that a reaction will produce 12.7 g of CO2(g). What volume of CO2(g) should be expected at a new temperature of 40.0°C and 120.0 kPa?

 

First, find the number of moles of carbon dioxide gas.

 

Now, determine the volume using the ideal gas law.

 

A volume of 6.26 L of CO2(g) should be expected.

 

As you can see by these examples, using the ideal gas law to predict the pressure, volume, or mass of gas can be very useful. One of the most practical reasons for using this relationship is to ensure the safety of people working with compressed gases and to ensure that the capacity of containers is not exceeded.

 

Self-Check

 

SC 7. What mass of neon gas should be introduced into an evacuated 0.88-L tube to produce a pressure of 90 kPa at 30°C?

 

SC 8. When an air bag is activated in a collision, sodium azide rapidly decomposes to produce nitrogen gas. Chemical engineers carefully choose the quantity of sodium azide to produce the required chemical quantity of nitrogen gas. Use the ideal gas law to predict the chemical quantity of nitrogen gas required to fill a 60-L air bag at a pressure of 233 kPa and a temperature of 25°C.

 

SC 9. At what temperature does 10.5 g of ammonia gas exert a pressure of 85.0 kPa in a 30.0-L container?

 

SC 10. Use the ideal gas law to determine three ways to reduce the volume of gas in the shock absorber (cylinder and piston) of an automobile.

 

SC 11. A 1.49-g sample of a pure gas occupies a volume of 981 mL at 42.0°C and 117 kPa.

1. Determine the molar mass of the compound.
2. If the chemical formula is known to be XH3, identify element X.

 

Module 3: Lesson 4 Assignment

 

You will use the following lab to complete part of your Lesson 4 Assignment.

 

Chemistry 20 © 2008 Alberta Education

Module 3—Behaviour of Gases

Lab: Molar Volume of an Ideal Gas

 

In chemistry, solving mathematical and scientific problems is often attempted in a laboratory. By using appropriate glassware, chemicals, equipment, and technology, you can complete experiments, record data, perform calculations based on the data, and draw conclusions.

 

The following lab activity will enable you to complete a virtual experiment to verify the molar volume of an ideal gas. At STP, the molar volume of a gas is 22.4 L/mol; and at SATP, the molar volume of a gas is 24.8 L/mol. This lab offers you an opportunity to test the molar volume of a gas with a different set of conditions, formulate a hypothesis, and test the results in the virtual lab.

 

Read through the Background, Procedure, and Assignment before beginning the lab.

 

Retrieve a copy of the Module 3: Lesson 4 Assignment. Complete Part 1; then save a copy of the assignment to your course folder.

 

Chemistry 20 © 2008 Alberta Education

Module 3—Behaviour of Gases

Reflect and Connect

 

Compressed Carbon Dioxide Cartridges

 

Throughout this module you are asked to consider technologies that apply the use of one or more of the gas laws. For your combined unit and module assessment, you will prepare a response on a technology that applies gas laws. To prepare your response, consider the following information on compressed carbon dioxide cartridges. Refer to the Unit Assessment section for more information.

 

Compressed carbon dioxide cartridges are a popular alternative to a hand pump for many cyclists. Since the size of the tires and the suggested optimal inflation pressure varies between mountain bikes and road bikes, different sizes of cartridges are available. Each size of cartridge has a different mass of carbon dioxide inside.

 

Describe advantages and disadvantages of the use of compressed carbon dioxide gas cartridges in place of a hand pump to inflate bicycle tires. Make sure your list addresses at least three different perspectives.

 

Save a copy of your list in your course folder. You may wish to use this explanation when completing the unit assessment. For more information on the unit assessment, refer to the Unit Assessment section.

 

Reflect on the Big Picture

 

Propane Cylinders

 

Throughout this unit you have been asked to consider technologies that apply the use of one or more of the gas laws. Consider the use of propane cylinders.

 

How does a technician at a filling station know when a propane cylinder is full? Can you think of how the ideal gas law applies to the filling of propane cylinders, like the cylinders used with many gas barbeques? How is the safety of gas cylinders determined at a filling station? Does this system have merit?

 

You may wish to use your response to this question as your module and unit assessment. Refer to the Unit Assessment document for more information.

Module 3: Lesson 4 Assignment

 

Retrieve the Module 3: Lesson 4 Assignment you saved to your course folder earlier in this lesson. Complete Part 2, and save a copy of your answers to your course folder.

 

Once you have completed all of the questions, submit your work to your teacher.

 

Chemistry 20 © 2008 Alberta Education

Module 3—Behaviour of Gases

Lesson Summary

 

In this lesson you investigated the following questions:

• What is molar volume?
• What is the difference between a real gas and an ideal gas?
• What relationship exists between pressure, volume, temperature, and moles of gas?

In this lesson you further interpreted laws and relationships among pressure, volume, temperature and amount of gas. You learned that molar volume has a different value at different conditions of temperature and pressure. You learned what aspects constitute ideal behaviour of a gas and how the ideal gas law can be used to perform meaningful calculations, some of which focused on ensuring safety for people using compressed gases.

 

Chemistry 20 © 2008 Alberta Education

Chemistry 20 © 2008 Alberta Education

Module 3—Behaviour of Gases

Module Glossary

 

There is no glossary for this module.

 

Chemistry 20 © 2008 Alberta Education