CENTRAL BICOL STATE UNIVERSITY OF AGRICULTURE CDE - Laboratory High School Pili, Camarines Sur Detailed Lesson Plan in Science and Technology III (Chemistry) 3-A & 3B, 2:00-4:00 pm February 6 & 8, 2012 PSSLC: VI.1 I. Objectives: At the end of the session, at least 85% of the students are expected to: General: 1. Demonstrate the understanding of the behavior of gases Specific: 1. Enumerate the properties and behavior of gases based on Kinetic Molecular Theory; 2. Solve problems on Boyle’s Law, Charles’ Law, and combine gas law 3. apply gas laws in explaining daily occurrences; and 4. Relate the properties of gases to air pollution. II. Subject Matter A. Topic: Gases Sub-topic: Boyle’s Law, Charles’ Law, Avogadro’s Law and Dalton’s Law of partial pressure; B. References: a. Chemistry for the New Millennium by Emil Soriano, et.al, pp. 240-260 b. http://www.chemprofessor.com/kmt.htm c. http://chemed.chem.purdue.edu/genchem/topicreview/bp/ch4/kinetic4.html d. http://www.chm.davidson.edu/vce/kineticmoleculartheory/basicconcepts.html e. http://www.scienceclarified.com/everyday/Real-Life-Physics-Vol-2/GasLaws-Real-life-applications.html#b C. Materials: Projector, computers with internet connection, impress presentation D. Concepts: The gas laws developed by Boyle, Charles, and Gay-Lussac are based upon empirical observations and describe the behavior of a gas in macroscopic terms, that is, in terms of properties that a person can directly observe and experience. An alternative approach to understanding the behavior of a gas is to begin with the atomic theory, which states that all substances are composed of a large number of very small particles (molecules or atoms). In principle, the observable properties of gas (pressure, volume, temperature) are the consequence of the actions of the molecules making up the gas.
E. Skills: identifying, describing, comparing, analyzing and developing scientific attitudes. F. Values Integration: awareness on the importance of scientific advancement in one’s daily existence, develop scientific values such as intellectual curiosity and creativity and respect and love for nature G. Time Frame: 120 minutes H. Strategy Applied: Inductive Method, 4A’s III. Teaching Procedure Time Teaching Hints Frame 3 min. A. Preliminary Activities 1. Greetings 2. Prayer
Teacher’s Activity
Student’s Activity
IMs
Good afternoon class! Good afternoon Ma’am! Everybody stand, kindly lead the prayer (Students will stand and somebody will lead the prayer.) Impress 3. Securing the Before taking your sits, arrange your presentation Cleanliness chairs first and pick up tiny pieces of dirt under your chairs. 4. Checking of Karen, who are absent for today? (The class monitor will recite the Attendance list of students who are absent.) Thank you, class monitor. 5. Checking of Have I given you an assignment last No Ma’am. Assignment meeting?
3 min. B. Recall
Okay. We are all surrounded by mixtures, and we all consume and use them in our daily living. We have mayonnaise for our sandwiches, gelatin as food, lotion to make our skin soft and smooth. So how do we classify these mixtures which are very useful to us? We call them colloids Very good!
Like solution colloids have two components these are: Great!
The two components of colloids are dispersed phase and dispersion medium.
So, do you have questions regarding that topic? None, Ma’am
5 min. C. Motivation
An inflated balloon will place on a pale of water with ice cubes
What have you observed? The diameter of the balloon becomes smaller as we soak it in the cold water.
Great observation! How about it we put it in a hot water?
It will be the opposite, it will become bigger. Nice, inference. (The teacher will spray a cologne / perfume) Now, what have you observed / smelled? It smells good. The perfume spreads all over the place. 1 min. D. Presentation of For this day, we’ll discuss about the the Lesson gases 1 min. E. Presentation of What do we have to learn for today? Objectives (Let the students read the objectives.) 3 min. F. Unlocking of Before we continue, let us first define Difficulties some important terms that will help us for a better understanding of our discussion. How will you define pressure? How about volume
Impress presentation Students will read the objectives.
Pressure is defined as force per unit area. The gas occupied space
And we define temperature as
The average Kinetic energy of molecules.
G. Lesson Proper 5min. 1. Pre-activity For our activity, I will group you into 3, discussion and then you will choose your leader. Each group will perform an activity, after which a representative per group will report the group’s work for the class. The activity will be good for 15 minutes and another 5 minutes will be allotted in answering the guide questions. We will be using a rubric in grading your group activity. PowerPoint Presentation
RUBRICS: Accuracy
– 40%
Cooperation – 10%. Discipline of the output– 30% Total
– 20%
Clarity
–100%
For the activity, I’ll provide you an index card where you can see the procedure to be followed by group. In presenting your work, you’ll follow this format flashed on the screen. Present your output in manila paper. Group # ____ Title of Activity: Materials: Procedure: Observation/s: Conclusions: So, do you have questions regarding to your activity? None, Ma’am! 20min.
2. Activity proper
Okay, so you can now do the activity. (The teacher will watch over the students’ perform of the activity.) Activity Sheet
(Students will perform the respective activity per group.)
GASES Group 1. Materials: 2 pcs rubber ballon, warm water, cold water, measuring tape/ string and ruler Procedure: 1. Inflate the 2 balloon and measure its diameter. They should be of the same size 2. Immerse the balloon in warm water in three minutes 3. The other balloon in cold water in three minutes also 4. compare the diameter before and after immersing them in cold and warm water. Points for Discussion: 1. What have you observed? 2. Illustrate your observation Group 2
Laboratory materials, manila paper, marker
Materials: 1 empty softdrink can, alcohol lamp, tong, basin containing ice and water Procedure: 1. Place the softdrink can on the lighted alcohol lamp with a small amount of water. 2. When the steam comes out the can, invert this into the basin of very cold water using a tong. Points for Discussion: 1. What have you observed? Illustrate your observation Group 3. Materials: Syringe. Clay weights
10 min.
10 min.
Procedure: 1. Fill the syringe with air and seal the tip of it with a clay 2. Apply pressure on the syringe by placing weights on it. Start adding weights from 50g to 250g. 3. Tabulate your data. Plot your data in a graph. Assign pressure on the y axis and mass in the xaxis. Give your observation 3. Post-activity How did you find the activity? Fun and knowledgeable. discussion (Representative per group will (Let each representative of the group present their works) discuss their works.) 4. Analysis For the activity of group 1, What are your observations? The volume of the balloons is affected by the temperature of the surrounding. Group 2’what’s your observation? The sudden change in the temperature of the can makes it to collapse. Group 3, your observation was? As we add more weights on the syringes the volume of the gases decreases.
10 min.
5. Abstraction Now, let us talk about gas
PowerPoint Presentation
We are surrounded by gases. Without gases we will die. But the presence of it in high concentration will be detrimental for us. Let’s have the Kinetic Molecular theory The experimental observations about the behavior of gases discussed so far can be explained with a simple theoretical model known as the kinetic molecular theory.
1. Gases are composed of a large number of particles that behave like hard, spherical
This theory is based on the following postulates, or assumptions.
objects in a state of constant, random motion. 2. These particles move in a straight line until they collide with another particle or the walls of the container. 3. These particles are much smaller than the distance between particles. Most of the volume of a gas is therefore empty space. 4. The force of attraction is almost negligible. 5. Collisions between gas particles or collisions with the walls of the container are perfectly elastic. None of the energy of a gas particle is lost when it collides with another particle or with the walls of the container. 6. The average kinetic energy of a collection of gas particles depends on the temperature of the gas and nothing else.
Okay, class gas laws that we use today describe the behavior of gases. Let’s have Boyles Law. Boyle’s Law states that, at temperature, pressure and volume are inversely proportional If the pressure and volume are inversely proportional, an increase in volume will lead to a decrease in pressure. If volume increases, the distance each particle travels before it hits the wall increases. This relation between the volume of the gas and the gasits pressure was analyzed by Robert Boyle in 1662. This is expressed mathematically: P1V1=P2V2 P1= initial pressure P2= final pressure V1=initial volume V2= final volume Let’s have an example problem A 200 cubic centimiter of gas contained Given: in a vessel undser a pressure of
850mmHg. What will be the new volume P1= 850mmHg if the gas pressure is changed to V1= 200cm 1000mmhg? P2= 1000mmHg F: V2 Formula: P1V1=P2V2 V2=
850mmHg)(200cm) 1000mmHg ( V2 = 170 cm
Nice answer. Another example, a 2.5 liter of gas sample is collected at a pressure of 1.25 Given: atm. Calculate the pressure needed to P1= 1.25atm reduce the volume of the gas to 2.0 liters V1= 2.5 L V2 = 2.0L F: P2 Formula: Great seems you have mastered calculating c\Boyle’s Law let’s have another gas law which is Charles Law. In 1787, Jacques Charles studied the relationship between the volume and temperature of gas using a balloon.
P1V1=P2V2 P2=
(1.25 atm)(2.5L) 2.0L P2 = 1.56atm
Which we call Charles law and
We mathematically expressed it as:
Take note class that only Kelvin is used in temperature.
Charles’ Law states that, at constant number of moles and pressure, the volume and the temperature are directly proportional. V1 = V2 T1 T2 Where: V1= initial volume of the gas V2 final volume of the gas T1= Initial temperature of the gas T2= final temperature of the gas.
Let’s have a sample problem.
The temperature of a gas in 2 L container is 300K.What will be its volume if the temperature is increased to 500K? Given: V1= 2L T1= 300K T2= 500K
.
Now class . we also have a combine Gas F: V2 Law Formula: It occurs when we consider both Boyles law and Charles Law P1V1 = P2V2 T1 T2
V1 = V2 T1 T2 2L = V2 300K 500K V2 = 3.33 L
This is expressed mathematically as: Let’s have a sample problem.
Combined Gas Law states that” for A gas occupies a volume of 3L at 323K a given mss of gas, the volume is and 1.50atmwith a final temperature of . inversely proportional to the pressure and directly proportional 298K Compute its volume at STP to its absolute temperature.
Given: P1 = 1.5 atm V1= 3L T1= 323 K P2= 1atm (STP) T2 = 298K F: V2 Formula: P1V1 = P2V2 T1 T2 Answer: 4.15L
5 min.
Do you have any questions? 6. Application Applications of gas laws are unlimited. And some are_____
None, Ma’am Possible answers: • OPENING A SODA CAN. Inside a can or bottle of carbonated soda is carbon dioxide gas (CO 2 ), most of
PowerPoint presentation
which is dissolved in the drink itself. But some of it is in the space (sometimes referred to as "head space") that makes up the difference between the volume of the soft drink and the volume of the container. At the bottling plant, the soda manufacturer adds highpressure carbon dioxide to the head space in order to ensure that more CO 2 will be absorbed into the soda itself. This is in accordance with Henry's law: the amount of gas (in this case CO 2 ) dissolved in the liquid (soda) is directly proportional to the partial pressure of the gas above the surface of the solution—that is, the CO 2 in the head space. The higher the pressure of the CO 2 in the head space, the greater the amount of CO 2 in the drink itself; and the greater the CO 2 in the drink, the greater the "fizz" of the soda. Once the container is opened, the pressure in the head space drops dramatically. Once again, Henry's law indicates that this drop in pressure will be reflected by a corresponding drop in the amount of CO 2 dissolved in the soda. Over a period of time, the soda will release that gas, and will eventually go "flat."
3 min. H. Generalization
Again, what are assumptions in Kinetic Molecular Theory?
1. Gases are composed of a large number of particles that behave like hard, spherical objects in a state of constant, random motion. 2. These particles move in a straight line until they collide with another particle or the walls of the container. 3. These particles are much smaller than the distance between particles. Most of the volume of a gas is therefore empty space.
4. The force of attraction is almost negligible. 5. Collisions between gas particles or collisions with the walls of the container are perfectly elastic. None of the energy of a gas particle is lost when it collides with another particle or with the walls of the container. 6. The average kinetic energy of a collection of gas particles depends on the temperature of the gas and nothing else.
5 min. I. Values Integration In terms on our daily living what is the importance of knowing the concepts of gas laws?
Possible answers: •
We use it when cooking using pressure cooker
•
We can lessen air pollution by knowing what are the properties of gases. Let’s stop burning stuffs at home
IV. Evaluation: (5 min.) 1. Solve the given problem using “GUES method” 1. A quantity of gas exerts a pressure of 2.4 atm when its volume is 4 L at 310K. Calculate the pressure exerted by the same gas if the temperature is raised to 330Kand the volume is 1.5L.
V. Assignment: (3 min.) 1. What are the applications of gas laws? Send your answer to
[email protected] State references used.
Prepared by:
Janine Pauline S. Sierda Chemistry Student Teacher Checked by:
Prof. Charlie P. Nacario Cooperating Teacher
Noted by:
Nelia A. Barce Coordinator, CDE-LHS
Prof. Nelia B. Arimado LHS-Principal
CENTRAL BICOL STATE UNIVERSITY OF AGRICULTURE CDE - Laboratory High School Pili, Camarines Sur
Less on Plan (Gas Law)
Janine Pauline S. Sierda
Chemistry Student Teacher
Prof. Charlie P. Nacario Cooperating Teacher
