Gas Laws Week 5&6 - General Chemistry 1 Quarter 2 Module 1-General Chemistry 1 for SHS PDF

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Senior High School

         

General Chemistry 1 Alternative Delivery Mode Quarter 1 – Module 11: Gas Laws First Edition, 2020 Republic Act 8293, section 176 states that: No copyright shall subsist in any work of the Government of the Philippines. However, prior approval of the government agency or office wherein the work is created shall be necessary for exploitation of such work for profit. Such agency or office may, among other things, impose as a condition the payment of royalties. Borrowed materials (i.e., songs, stories, poems, pictures, photos, brand names, trademarks, etc.) included in this module are owned by their respective copyright holders. Every effort has been exerted to locate and seek permission to use these materials from their respective copyright owners. The publisher and authors do not represent nor claim ownership over them. Published by the Department of Education, Division of Palawan Schools Division Superintendent: Natividad P. Bayubay, CESO VI Assistant Schools Division Superintendents: Loida Palay-Adornado, Ph.D. Felix M. Famaran

Development Team of the Module Writer: Ranlee John Baynosa Content Editor: Jecelle A. Jaranilla Language Editor: Aldrin V. Gongob Illustrator: Harold Garcellano Management Team: Aurelia B. Marquez Rodgie S. Demalinao Rosalyn C. Gadiano

Printed in the Philippines, by ________________________ Department of Education – MIMAROPA Region – Division of Palawan Office Address: Telephone: E-mail Address: Website:

PEO Road, Barangay Bancao-Bancao, Puerto Princesa City (048) 433-6392 [email protected] www.depedpalawan.com

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Introductory Message For the facilitator: Welcome to the General Chemistry 1 Alternative Delivery Mode (ADM) Module on Gas Laws! This module was collaboratively designed, developed and reviewed by educators both from public and private institutions to assist you, the teacher or facilitator in helping the learners meet the standards set by the K to 12 Curriculum while overcoming their personal, social, and economic constraints in schooling. This learning resource hopes to engage the learners into guided and independent learning activities at their own pace and time. Furthermore, this also aims to help learners acquire the needed 21st century skills while taking into consideration their needs and circumstances. In addition to the material in the main text, you will also see this box in the body of the module:

Notes to the Teacher In view to the new normal world we are facing, this module was created to answer that education should not stop for our learners. This General Chemistry 1 Module for Quarter 1 is all about the Gas Laws. With this we are trying to allow our learners to work independently in discovering through simple and enjoyable activities/ experimentation that are aligned to the competencies that they should learn.

As a facilitator, you are expected to orient the learners on how to use this module. You also need to keep track of the learners' progress while allowing them to manage their own learning. Furthermore, you are expected to encourage and assist the learners as they do the tasks included in the module.

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For the learner: Welcome to the General Chemistry 1 Alternative Delivery Mode (ADM) Module on Gas Laws! This module was designed to provide you with fun and meaningful opportunities for guided and independent learning at your own pace and time. You will be enabled to process the contents of the learning resource while being an active learner. This module has the following parts and corresponding icons: What I Need to Know What I Know

What’s In

What’s New

What is It

What’s More

What I Have Learned

What I Can Do

This will give you an idea of the skills or competencies you are expected to learn in the module. This part includes an activity that aims to check what you already know about the lesson to take. If you get all the answers correct (100%), you may decide to skip this module. This is a brief drill or review to help you link the current lesson with the previous one. In this portion, the new lesson will be introduced to you in various ways; a story, a song, a poem, a problem opener, an activity or a situation. This section provides a brief discussion of the lesson. This aims to help you discover and understand new concepts and skills. This comprises activities for independent practice to solidify your understanding and skills of the topic. You may check the answers to the exercises using the Answer Key at the end of the module. This includes questions or blank sentence/paragraph to be filled in to process what you learned from the lesson. This section provides an activity which will help you transfer your new

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knowledge or skill into real life situations or concerns. Assessment

This is a task which aims to evaluate your level of mastery in achieving the learning competency.

Additional Activities

In this portion, another activity will be given to you to enrich your knowledge or skill of the lesson learned.

Answer Key

This contains answers to all activities in the module.

At the end of this module you will also find: References

This is a list of all sources used in developing this module.

The following are some reminders in using this module: 1. Use the module with care. Do not put unnecessary mark/s on any part of the module. Use a separate sheet of paper in answering the exercises. 2. Don’t forget to answer What I Know before moving on to the other activities included in the module. 3. Read the instruction carefully before doing each task. 4. Observe honesty and integrity in doing the tasks and checking your answers. 5. Finish the task at hand before proceeding to the next. 6. Return this module to your teacher/facilitator once you are through with it.

If you encounter any difficulty in answering the tasks in this module, do not hesitate to consult your teacher or facilitator. Always bear in mind that you are not alone. We hope that through this material, you will experience meaningful learning and gain deep understanding of the relevant competencies. You can do it!

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What I Need to Know

This module was designed and written with you in mind. It is here to help you master the nature of Chemistry. The scope of this module permits it to be used in many different learning situations. The language used recognizes the diverse vocabulary level of students. The lessons are arranged to follow the standard sequence of the course. But the order in which you read them can be changed to correspond with the textbook you are now using. The module contains the lesson about: •

Lesson 1 – Gas Laws!

After going through this module, you are expected to: 1. define Pressure; 2. identify the common units of pressure; 3. identify the gas laws to explain the pressure, volume, and temperature relationships of a gas under certain condition of change; 4. express the gas laws in equation form; 5. compute word problems involving gas laws; 6. identify the relationships among pressure, volume, temperature or number of moles of gas using the ideal gas equation; 7. solve problems using ideal gas equation; 8. utilize Dalton’s law of partial pressure to explain mole fraction and partial pressure of gases in mixture; and 9. compute word problems using Dalton’s law of partial pressure.

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What I Know Directions: Read the following questions carefully. Encircle the letter of the best answer. 1. The amount of force exerted by an object on a certain area is known as____. a. acceleration c. velocity b. pressure d. newton 2. The following are the most common units use in quantifying pressure EXCEPT _________. a. torr c. atmospheric pressure b. pascal d. Weber 3. Increasing the number of air molecules contained in a basketball will likely increase its volume. This is according to __________. a. Boyle’s law c. Avogadro’s law b. Charles’ law d. Lavoisier’s law 4. According to Charles’ law, the volume of gases at constant pressure is directly proportional to the temperature in which the gas is exposed. This statement is represented by which of the following mathematical equation? a. VT= k c. V/T= k b. T/V =k d. PV= k 5. You observed that as the bubble goes up from the bottom of the sea to the surface of the water, its size changes and grow bigger. What would be the BEST conclusion about the relationship of pressure and volume based on the situation given? a. Pressure and volume is inversely proportional at constant temperature. b. Pressure and volume is directly proportional at constant temperature. c. Volume of the bubble is not affected by the pressure under the sea. d. Pressure under the sea is lesser compare to the surface which allows the bubble to expand. 6. If the volume available to an ideal gas is increased, the pressures exerted by one mole of gas molecules will _____________. a. Increase c. Decrease then increase b. Decrease d. Remains the same 7. Calculate the pressure exerted by 0.300 mole of gas contained in an 8.00 liters vessel at 18°C. (***R=0.0821 Latm/molK) a. 0.986 atm c. 0.896 atm b. 1.001 atm d. 0.789 atm 1

8. The total pressure of a mixture of non-reacting gases is equal to the sum of the partial pressures of the individual gases. This is according to _____________. a. Gay-Lussac’s law b. Boyle’s law c. Avogadro’s law d. Dalton’s law of partial pressure 9. What is the partial pressure of nitrogen gas in container that holds 8.0 moles of CO2, 5.0 moles of N2, and 2.0 mole of H2 and has a total pressure of 3.00 atm? a. 1.60 atm c. 2.49 atm b. 1.00 atm d. 1.57 atm 10. At 30°C, the volume of a sample of air was 5.8-L what would be the volume of the air sample if it is heated to 60°C at the same pressure? a. 6.37-L c. 100-L b. 7.22-L d. 2.71-L 11. A barometric reading of 950 mmHg is recorded in a barometer at the top of the mountain. Convert this value to standard atmospheric pressure (atm) unit. (*** 1 atm=760 mmHg) a. 1.25 atm c. 722, 000 atm b. 1.25 mmHg d. 722, 000 mmHg 12. A balloon with an initial volume of 1.1 liters at room temperature (25°C) is placed in a tub full of cold water with a temperature of -10°C. What will happen to the volume of the balloon as it is placed inside the tub? What is its volume? a. Increase in volume: 2.2 liters b. Increase in volume: 1.9 liters c. Decrease in volume: 0.75 liters d. Decrease in volume: 0.97 liters 13. A plastic balloon containing 2.00 moles of helium has a volume of 0.88 liters. What is the new volume after 6.00 moles of helium are added to the balloon at the same temperature and pressure? c. 2.640 liters a. 880 liters b. 2640 liters d. 5,280 liters 14. The pressure of an ideal gas in a sealed container of volume V is

increased from P to 3P. What will happen to the volume, V of this gas? a. There is no change. c. increases from V to 3V. b. decreases to V/3. d. increases from V to 2V. 15. The temperature of a fixed mass of gas increases from 100K to 400K. What will happen to its volume? It will ________. a. stay the same. b. double. c. increase by a factor of four (four times its original volume). d. decrease to a quarter of its original volume. 9

Lesson

Gas Laws

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Earth is surrounded by a mixture of gases known as atmosphere. In this vast portion of Earth, never-ending reactions take place and many of them are determined by the energy from the sun. In this lesson, you are going to learn the underlying concept of how balloons inflate as you blow air in it, how hot air balloon goes up, how divers able to dive in an endless water with oxygen tank and some of the most common real-life scenario you probably encounter in your everyday life.

What’s In The next activity will help you check how profound your understanding about the previous lesson is. This will enable you to self-reflect if you are wellprepared to take on your science journey or you still need some supplementary information to acquire. Activity 1: Chem-rades! Directions: Guess the word out of words. Write your answer on the space provided. Example: Charade Came Mist Three

Hidden term Chemistry

Charade

Hidden term

1. Tea you ray thee call yelled 2. Ache wall yelled 3. Pear scent age yelled 4. Ray ache taunt 5. Must ray lay shown shape 6. Lay may thing ray ache taunt 7. Ex seas ray ache taunt 8. Came make all ache way shown

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9. Proud duck 10. Came meek all ray ache shown

What’s New Gas Pressure One of the most important properties of any gas is its pressure. The firmness of a balloon filled with air indicates that the gas inside exerts pressure. This pressure is caused by gas molecules striking the balloon’s inner surface with each collision exerting a force on the surface. The amount of force exerted in a specific area is what we call pressure. It is given as:

Where:

𝐅 P= 𝐀

P= Pressure F= Force A= Area

Gas Pressure: Units and Conversions Gas particles in the atmosphere have mass and are pulled toward the Earth by gravity where they exert pressure on every surface it contacts. This pressure is known as the atmospheric pressure. Atmospheric pressure can be measured with a barometer. Pressure measured with a mercury barometer is usually reported in millimeters of mercury (mmHg), a unit that is also called the torr after Evangelista Torricelli, who invented the mercury barometer in 1643. The standard atmosphere (atm) is defined as 1 standard atmosphere = 1 atm = 760 mmHg = 760 torr = 101.325 kPa The table below shows some of the most common units and conversion factors use in quantifying gas pressure: Table 1. Pressure Units SI Unit: Pascal (Pa) 1 Pa = 1 N/m2 ; 1 kPa = 103 Pa Other Common Units 1 bar = 105 Pa = 100 kPa ; 1 millibar (mbar) = 102 Pa 1 atm = 1.01325 x105 Pa = 101.325 kPa 1 atm = 760 torr = 760 mmHg (this conversion is exact)* 1 atm = 14.7 lb/inch2 (psi) = 1.01325 bar 11

There are some instances in this lesson that you will be instructed to convert the units of the variable that you are going to use in solving word problems and other related mathematical computation. Example 1: 1. What is the pressure (in atmospheres) of a gas that has a pressure of 600 torr? Solution 1: To solve this problem, you must first identify the conversion factor such as; there is 1 atm in every 760 torr, thus 600 torr

×

1 atm

760 torr

= 0.789 atm

Example 2: 2. The pressure of a gas is measured as 980 mmHg. Express this pressure in atmosphere. Solution 2: Conversion factor: 1 atm = 760 mmHg 1 atm 980 mmHg × = 1.29 atm 760 mmHg Try this: 3. A sample of hydrogen gas has a pressure of 0.75 atm. Give the pressure

of hydrogen in torr. Aside from pressure, gas can also be measured and described with the other parameters (or variables) such as volume, temperature, and amount of gas (n, mole). Volume: the space occupied by a certain gas. It is equal to the volume of the container inasmuch as a gas completely fills its container. The common unit for volume is the liter (L), but the SI unit for volume is m3. The equivalence of liter in SI units is simple: 1 cubic meter (m3) = 1000 liters (L) 1 cubic decimeter (dm3) = 1 liter (L) 1 cubic centimeter (cm3) = 1 milliliter (mL) Temperature: Determines the average kinetic energy of a body. The common unit for temperature is degree Celsius (°C), but the SI unit is Kelvin (K). The Kelvin temperature is used in all calculations with gases. 12

The relationship between the units is: K = °C + 273.15 Amount of Gas: the quantity of the particles of gas added on a system. In gas laws, the amount of gas in a container is usually expressed in moles (n).

What is It Gas Laws: Pressure, Volume, Relationship

Temperature

and

Amount

of

Gas

Gases have been studied for hundreds of years, and the properties that all gases display have been summarized into gas laws that are named for their discoverers. Using the variables such as pressure, volume, temperature and amount of gas (number of moles); we can write equations that explain how gases behave. That behaves exactly as described by these equations is called an ideal gas. The Pressure-Volume Relationship: BOYLE’S LAW Boyle’s law states that the volume (V) of an ideal gas varies inversely with the applied pressure (P) when temperature (T) and amount of gas (n, moles) are constant. In mathematical terms, the initial pressure P1 multiplied by the initial volume V1 of a gas gives a constant value k P 1 V1 = k If the volume or pressure of the gas changes without changing the temperature or the amount of the gas, the final pressure and volume will be equal to the same constant. P 2 V2 = k Hence, the relation of the initial and final products of the volume and pressure of a gas may be written as:

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P1 V1 = P2 V2 (at constant T and n) Table 2. Examples of Pressure-Volume Relations and its graphical representation

Consider the situation below: 1. A sample of oxygen gas (O2) has an initial volume of 8.0 L and a pressure of 1.0 atm. What is the new pressure if the volume is decreased to 2.0 L? Step 1: Analyze the stem of the word problems and identify the known and the unknown variables. Known Variables: V1 = 8.0 L P1 = 1.0 atm V2 = 2.0 L Unknown Variable: P2 = ?

Some clues can be used to identify the right variable and its numerical value in the problem. Words such as “initial”, “new” are some of them. • Make sure that the units of the variables are scientifically correct. • Convert the units if it is needed to convert.

•

Step 2: Express the known and unknown variables into mathematical equation. Remember this equation?

P 1 V 1 = P2 V 2

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P 1 V1 = P 2 V2 V2 V2 Final equation: P 2 = P 1 V1 V2

•

Rearrange the equation to get the correct formula to compute the unknown.

Step 3: Substitute the value to its corresponding variables.

• Compute the problem P2 = (1.0 atm) (8.0 L) 2.0 L • Cancel the unnecessary units to Final answer: 4.0 atm arrive with the correct one. ***Interpretation: The pressure is increased which affects the volume of • Make an interpretation from the the gas to occupy a smaller volume. answer you computed. Try this! 1. A sample of a gas has a pressure of 0.4 atm in a sealed 0.125-L flask. If the gas sample is transferred to another flask with a volume of 0.2-L, what will be the new pressure in mmHg? Assume that the temperature remains constant. (***must convert your final answer to mmHg using the conversion factors on table 1)

Solution:

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The Temperature-Volume Relationship: CHARLES’S LAW Charles’s law states that the volume (V) of an ideal gas varies directly with absolute temperature (T) when pressure (P) and amount of gas (n) are constant. 𝑽∝𝑻

𝑽

(V= constant (k) x T)

𝑻

= k (depends on pressure

and the amount of the gas. If the volume, V1, and temperature, T1, of a sample of gas are known, then the volume V 2, at some other temperature, T2, at the same pressure is given by unchanging P and n) The value of the constant

𝑉1 𝑇1

=

𝑉2

𝑇2

(P and n constant)

Graph 2. Graphical Representation of Volume-Temperature relationship

Consider the situation below: Example 1: 1. A sample of neon gas at 760 mmHg has a volume of 10.0 L and a temperature of 34°C. Find the new volume of the gas after the temperature has been increased to 75°C at constant pressu...