Science 10 Quarter 4 Module 1 Layout PDF

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Department of Education National Capital Region

SCHOOLS DIVISION OFFICE MARIKINA CITY

Science Quarter 4 – Module 1 Behavior of Gases

Guiller P. Belen Daniel C. Villanueva

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What I Need to Know The purpose of this module is to help you understand how gases behave based on the motion and relative distances between gas particles. The module contains a lesson: Behavior of Gases. After going through this module, you are expected to investigate and explain the relationship between the properties of gases using kinetic molecular theory. Specifically, you are expected to: ● state the Kinetic Molecular Theory; ● investigate the relationship between volume and pressure at a constant temperature of a gas; ● investigate the relationship between volume and temperature at a constant pressure of a gas; ● explain volume-pressure and volume-temperature relationships using the kinetic molecular theory; and ● solve sample problems involving Gas Laws.

What I Know Read each item carefully and encircle the letter of the correct answer. 1. If a balloon is squeezed, what happens to the pressure of the gas inside the balloon? A. It increases. B. It decreases. C. It stays the same. D. The pressure depends on the type of gas in the balloon. 2. If a balloon is heated, what happens to the pressure of the air inside the balloon if the volume remains constant? A. It increases. B. It decreases. C. It stays the same. D. The change cannot be predicted.

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3. If a sample of helium gas has a volume of 120 mL and a pressure of 850 mm Hg, what is the new volume if the pressure is changed to 425 mm Hg ? A. 60 mL B. 120 mL C. 240 mL D. The change cannot be predicted. 4. Which statement best explains why a hot-air balloon rises when the air in the balloon is heated? A. Hot air rises inside the balloon, and this lifts the balloon. B. The temperature of the gas is directly related to its pressure. The pressure therefore increases, and this lifts the balloon. C. The temperature of a gas is directly related to its volume. Thus, the volume of the balloon increases, making the density smaller. This lifts the balloon. D. Some of the gas escapes from the bottom of the balloon, thus decreasing the mass of gas in the balloon. This decreases the density of the gas in the balloon, which lifts the balloon. 5. Which phenomenon best illustrates Charles’ Law? A. Carbon dioxide is dissolved in water. B. Breathing apparatus being used by a patient C. The leavening agent causing the fluffiness of cake products D. Expansion of the balloon as it is being submerged in hot water 6. A balloon with a volume of 200mL at 30 oC is submerged in hot water to obtain a temperature of 50 oC. Which of the following is expected to happen to the volume of the balloon if the pressure is kept constant? A. The volume of the balloon will become higher than 200 mL. B. The volume of the balloon will become lower than 200 mL. C. The volume of the balloon will stay the same. D. There is not enough data. 7. Why is gas easier to compress than liquid and solid? A. The volume increases more under pressure than an equal volume of solid does. B. Its volume increases more under pressure than an equal volume of liquid does. C. The volume of gas particles is larger compared to the overall volume occupied by the gas. D. The space between gas particles is much larger than the space between liquid or solid particles.

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8. Consider a 1.0L container of Neon gas at 273 K and 1 atm. In which of the following conditions will the average kinetic energy increase? I. The temperature increased to 1000C. II. The temperature is decreased to 500C. III. The volume has decreased to 0.5L. IV. The number of moles of neon is doubled. A. I only B. II only C. I and III D. I, II, and IV 9. When the Kelvin temperature of an enclosed gas doubles, how do the particles of the gas move at a certain temperature? A. Move faster B. Decrease in volume C. Decrease in average kinetic energy D. Strike the walls of the container with less force 10. Which type of gas is the basis for the kinetic-molecular theory? A. Real gas B. Ideal gas C. Perfect gas D. Smelly gas

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Lesson

Behavior of Gases

What’s In Identify the term being described. 1. Force exerted on an area S 2. Amount of space an object occupies L 3. Average kinetic energy of the gas particles P 4. Number of atoms contained in the substance A

U

What’s New OBSERVING THE BEHAVIOR OF GASES You will need: Balloon Pen and paper Procedures: (Do this at daytime) 1. Inflate the balloon. 2. Place the balloon under the sun. 3. Observe what happens.

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Guide Questions: 1. Describe the balloon before and after the exposure to the sun. _____________________________________ _____________________________________ 2. Illustrate your observations inside the box. You may use these guides: dots or small circles = gas particles arrow = direction of the motion of gas particles shorter arrow =slower movement longer arrow = faster movement

VOLUME VS. PRESSURE Procedures: 1. Analyze Table 1 showing the relationship of pressure and volume at constant temperature and amount of substance. 2. Construct a graph by plotting pressure against volume. 3. Answer the questions that follow. Table 1. Data on Pressure and Volume Pressure (atm)

Volume (mL)

1.0

10.0

2.0

5.0

3.0

3.3

4.0

2.5

5.0

2.0

6.0

1.6

7.0

1.4

Title of the Graph: _______________________

Guide Questions: 1. As the pressure increases, what happens to the volume? ___________________________________________________________________________ 2. What relationship exists between pressure and volume at same amount of gas and constant temperature? ___________________________________________________________________________

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VOLUME VS. TEMPERATURE Procedures: 1. Analyze Table 2 which shows the relationship of volume and temperature at constant pressure and amount of substance. 2. Construct a graph by plotting volume against temperature. 3. Answer the questions that follow. Table 2. Data on Volume and Temperature Volume (mL)

Temperature (K)

5.0

100.0

10.0

200.0

15.0

300.0

20.0

400.0

25.0

500.0

30.0

600.0

35.0

700.0

Title of the Graph: _______________________

Guide Questions: 1. As the volume increases, what happens to the temperature? _________________________________________________________________________ 2. What relationship exists between volume and temperature at the same amount of gas and constant temperature? _______________________________________________________________________________

What Is It Kinetic Molecular Theory While doing the activity, you have noticed that gases exhibit changes in behavior if they are subjected to changes in temperature. These behaviors may be explained through the Kinetic Molecular Theory which has the following assumptions: 1. The volume of the individual particles of a gas is so small that it is incomparable to the volume of the gas itself.

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2. These particles are in constant random motion which moves in a straight line until it hits another particle or a wall. 3. These particles have no force of attraction on each other or on the wall. 4. When two particles collide or a particle hits a wall, the total kinetic energy is conserved. No energy is gained or lost by the particle. 5. The absolute temperature affects the kinetic energy of the particles; the higher the temperature, the higher the average kinetic energy of gas particles. This means that at absolute zero, the particles’ motion stops.

Figure 1. Gas Particles (A) moving particles in a constant random straight line; (B) the particles are not affected by each other; (C) gas particle showing elastic collision; (D) gas particle after an increase in temperature

These assumptions are true for ideal gases but may still be applied in real gases. Ideal gases are hypothetical gases that follow these assumptions. Also, Kinetic molecular theory supports the different gas laws that explain the relationship among the properties of gases. Boyle’s Law Boyle’s law states that the volume of a fixed quantity of gas maintained at constant temperature is inversely proportional to the pressure. 1 𝑃 ∝ 𝑉 When two measurements are inversely proportional, one gets smaller as the other gets larger.

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Boyle’s law can be expressed in mathematical terms: 𝑃𝑉 =𝑘 or 𝑃1 𝑉1 = 𝑃2 𝑉2 The value of the constant depends on the temperature and the amount of gas in the sample. Try to analyze and understand the example problem related to Boyle’s law: A gas at 1.0 atm of pressure occupies a volume of 2.0 L. What is the new volume occupied by the gas if the pressure is reduced to 0.5 atm? The temperature and amount of gas are held constant. Given: P1 = 1.0 atm P2 = 0.5 atm V1 = 2.0 L V2 = ? Formula when the pressure is changed from 1.0

(b) Figure 2. Gas particle contained in (a) small volume and (b) large volume having the same number and temperature.

The pressure is determined by how many times each particle hits the wall. If the gas is contained in a small volume with no change in temperature and amount of substance, it is more likely for the particle to hit the wall many times as compared with gases contained in larger volumes. Figure 2 shows that at the same number of particles and the same temperature, there are more times these particles hit the wall as depicted by the hollow circles at the walls. Inversely, when the volume is large, the particles less likely to hit the walls, thus, lower pressure. Charles’ Law Charles’ law states that the volume of a fixed amount of gas maintained at constant pressure is directly proportional to its absolute temperature. 𝑉 ∝ 𝑇

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When two measurements are directly proportional, one increases as the other increases. Charles’ law can be expressed in mathematical terms below: 𝑉 =𝑘 𝑇 or 𝑉1 𝑉2 = 𝑇1 𝑇2 The value of the constant depends on the pressure and the amount of gas. The Kelvin scale is also known as the absolute temperature scale. On this scale 0 K, which is called absolute zero, is equal to -273.15 C. The unit of temperature to be used in Charles’ law is Kelvin. Try to analyze and understand the example problem related to Charles’ law: A gas occupies a volume of 10.0 L at 300.0 K under constant pressure and number of molecules. If the temperature is increased to 500.0 K, what will be the new volume occupied by the gas? Given: V1 = 10.0 L V2 = ? T1 = 300.0 K T2 = 500.0 K

Solution:

Answer: V2 = 16.67 L The new volume occupied by the gas when the temperature is changed from 300.0 K to 500.0 K is 16.67 L.

Formula

As the temperature is increased in the container, the particles are likely to move faster and will hit the wall of the container frequently. In order to keep the pressure constant, the volume of the container should increase, which is true if the container is not rigid. Figure 3 shows that when the particles’ temperature is low it exerts lower pressure on the walls of the container but when the temperature is

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increased, the particle exerts more forces on the wall which causes it to expand. This expansion is to compensate the pressure that is to be held constant.

What’s More Answer the following problems. Show your complete solution by following the GFSA (Given, Formula, Solution, and Answer) method. 1. A balloon is filled with 100.0 L of air at 1.300 atm pressure. What pressure is needed to change the volume to 25.00 L?

(a)

(b)

Figure 3. Gas particle contained in (a) small volume and (b) large volume having the same count and pressure but shows and increased in temperature depicted by the size of the arrow.

Given:

Solution:

Formula:

Answer:

2. A gas occupies 900.0 mL at a temperature of 300.0 K. What is the volume at 405.0 K? Given:

Solution:

Formula:

Answer:

What I Have Learned Answer the following questions. 1. What does Kinetic Molecular Theory state? ___________________________________________________________________________

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2. What relationship exists between the volume and pressure of gases at constant temperature? ___________________________________________________________________________ 3. What relationship exists between the volume and temperature of gases at constant pressure? ___________________________________________________________________________

What I Can Do A. Fill in each blank with the appropriate word chosen from the given options in the box below. greater compressed

increases decreases

Boyle's Law explains how the volume of a gas varies with the surrounding pressure. Scuba diving is one of the many applications where the concept of the law is applied. In diving, as a diver descends, the water pressure around him ___________, causing air in scuba equipment and lungs to become ___________. As he ascends, water pressure ___________, so the air in the equipment and body expands to occupy a ___________ volume. B. Fill in each blank with the appropriate word chosen from the given options in the box below. cooled rises

heated temperature

pressure less dense

Hot air balloons follow Charles’ law. When the balloon is ___________ air inside it expands and then it ___________. The warm air in the balloon is ___________than the surrounding cool air at the same ___________. The difference in density of the air inside and outside the balloon causes it to ascend. Similarly, the balloon will descend when it is ___________.

Additional Activities Answer the following problems. Show your complete solution by following the GFSA (Given, Formula, Solution, and Answer) method.

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1. What is the volume of a gas in a balloon that occupies 0.620 L at 298 K if the temperature is lowered to 273 K?

2. If 25 mL of a gas is compressed from 2.0 atm of pressure to 4.0 atm of pressure, what is the new volume at constant temperature?

Read each item carefully and encircle the letter of the correct answer. 1. Jane can still pump air in the party balloon even though it is already inflated. What explains this phenomenon? A. Balloons look better if their size is bigger. B. Balloons are made up of plastic. C. The air inside the balloon is hot. D. Air molecules can be compressed. 2. What happens to the lungs of a scuba diver as it moves closer to the seafloor? A. The lungs compress. B. The lungs expand. C. The lungs explode. D. There is no change in the lungs. 3. Which phenomenon best illustrates Charles’ Law? A. Carbon dioxide is dissolved in water. B. Breathing apparatus being used by a patient C. Leavening agent causing the fluffiness of cake products D. Expansion of the balloon as it is being submerged in hot water 4. Records show that the incidence of tire explosion is high during the summer season. Which of the following gives the best explanation for this observation? A. There are more travelers during summer vacation. B. Vehicles’ tires are not well maintained. C. There is too much air inside the tires. D. High temperature during the summer season causes the air inside the tire to expand.

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5. If the temperature of a fixed quantity of gas decreases and the pressure remains unchanged, A. its volume increases. C. its volume is unchanged. B. its volume decreases. D. its volume is neglected. 6. How can you possibly prove that gases have negligible mass? A. Put a balloon in a digital balance before and after you fill it with air. B. Feel the weight of the samples on both hands. C. Ask two persons to hold a box filled with air. D. Support your claim through equation. 7. What is NOT an assumption of the kinetic molecular theory to the motion of the gas? A. It moves in a straight-line motion. B. It moves in a constant motion. C. It moves in random motions. D. It moves in a curved path. 8. Which is an assumption of the kinetic molecular theory? A. The particles of gas have a distinct volume measured in mL. B. The particles of gas attract one another via intermolecular forces. C. The particles of gas collide and emit energy to the surroundings. D. The speed of the particles in a gas is directly proportional to the Kelvin temperature. 9. A gas occupies a volume of 2.0 L at a pressure of 1.0 atm. If the volume of the gas decreases to half of its original value, what is its new pressure if the temperature remains unchanged? A. 0.5 atm B. 1.0 atm C.1.5 atm D. 2.0 atm 10. The pressure of a gas is kept constant. If the initial temperature is doubled, what will happen to the volume it occupies? A. It will be doubled. B. It will be the same value as the pressure. C. It will decrease to half of its original value. D. Nothing will change in the volume.

Gibb, Nathalie. How does Boyle’s Law Apply to Scuba Diving. Retrieved from https://www.liveabout.com/boyles-law-and-scuba-diving-2962935 Kinetic Molecular Theory | Boundless Chemistry (lumenlearning.com) retrieved from https://courses.lumenlearning.com/boundlesschemistry/chapter/kinetic-molecular-theory/

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WHAT’S IN Pressure Volume Temperature Amount of Substance

WHAT’S NEW Activity 1 The balloon increases in size. (your illustration should show particles moving in random direction. All lines should be straight. Activity 2 The volume decreases. The relationship between volume and pressure is inverse. Activity 3 As the volume increases, temperature also increases. The relationship between volume and temperature is direct.

WHAT’S MORE 2.2 L 1,215 mL WHAT I HAVE LEANRED Kinetic Molecular Theory states that gas particles are in constant motion and exhibit perfectly elastic collisions. Inverse relationship Direct Relationship WHAT I CAN DO A. Increases Compressed Decreases Greater B. Heater Rises Less Dense Pressure Cooled

Answer Key Young, H. D., Freedman, R. A., Ford, A. L., & Sears, F. W. (2014). In Sears and Zemansky's university physics: With modern physics (pp. 1078-1151). Harlow, Essex, England: Pearson Education. Serway, R. A., & Vuille, C. (2014). In College physics (pp. 732-782). Australia: Brooks/Cole.

Development Team of the Module Writer:

Guiller P. Belen Daniel C. Villanueva

Content Editors:

Alma B. Castaño Edna R. Francisco Jessica S. Mateo Lei B. Penaflor
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