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/Gas-Laws-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
Frame Teaching Hints Teacher’s Activity Student’s Activity IMs
3 min. A. Preliminary Activities
Impress presentation 1. Greetings Good afternoon class! Good afternoon Ma’am!
2. Prayer Everybody stand, kindly lead the prayer (Students will stand and somebody will lead the prayer.)
3. Securing the Cleanliness
Before taking your sits, arrange your chairs first and pick up tiny pieces of dirt under your chairs.
4. Checking of Attendance
Karen, who are absent for today? Thank you, class monitor.
(The class monitor will recite the list of students who are absent.) 5. Checking of
Assignment
Have I given you an assignment last meeting?
Okay.
No Ma’am.
3 min. B. Recall 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?
Very good!
We call them colloids
Like solution colloids have two components these are:
Great!
So, do you have questions regarding that topic?
The two components of colloids are dispersed phase and dispersion medium.
5 min. C. Motivation An inflated balloon will place on a pale of water with ice cubes
What have you observed? Great observation!
How about it we put it in a hot water?
Nice, inference.
(The teacher will spray a cologne / perfume)
Now, what have you observed / smelled?
The diameter of the balloon becomes smaller as we soak it in the cold water.
It will be the opposite, it will become bigger.
It smells good. The perfume spreads all over the place. 1 min. D. Presentation of
the Lesson
For this day, we’ll discuss about the gases
Impress presentation 1 min. E. Presentation of
Objectives
What do we have to learn for today? (Let the students read the objectives.)
Students will read the objectives.
3 min. F. Unlocking of
Difficulties Before we continue, let us first define some important terms that will help us for a better understanding of our discussion.
How will you define pressure?
How about volume
And we define temperature as
Pressure is defined as force per unit area.
The gas occupied space The average Kinetic energy of molecules.
G. Lesson Proper 5min. 1. Pre-activity
discussion
For our activity, I will group you into 3, 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.
RUBRICS:
Accuracy – 40%
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Cooperation – 10%.
Discipline – 20% Clarity of the output– 30%
Total –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! Okay, so you can now do the activity.
20min. 2. Activity proper
(The teacher will watch over the students’ perform of the activity.)
(Students will perform the respective activity per group.) Activity Sheet
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
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 x-axis. Give your observation
10 min. 3. Post-activity
discussion How did you find the activity? (Let each representative of the group discuss their works.)
Fun and knowledgeable. (Representative per group will present their works)
10 min. 4. Analysis For the activity of group 1, What are your observations?
Group 2’what’s your observation?
Group 3, your observation was?
The volume of the balloons is affected by the temperature of the surrounding.
The sudden change in the
temperature of the can makes it to collapse.
As we add more weights on the syringes the volume of the gases decreases.
10 min.
5. Abstraction Now, let us talk about gas
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
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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.
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 in a vessel undser a pressure of
Boyle’s Law states that, at
temperature, pressure and volume are inversely proportional
850mmHg. What will be the new volume if the gas pressure is changed to
1000mmhg?
Nice answer.
Another example, a 2.5 liter of gas sample is collected at a pressure of 1.25
atm. Calculate the pressure needed to reduce the volume of the gas to 2.0 liters
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. Which we call Charles law and
We mathematically expressed it as:
Take note class that only Kelvin is used in temperature.
Let’s have a sample problem.
P1= 850mmHg V1= 200cm P2= 1000mmHg F: V2 Formula: P1V1=P2V2 V2= 850mmHg)(200cm) 1000mmHg ( V2 = 170 cm Given: P1= 1.25atm V1= 2.5 L V2 = 2.0L F: P2 Formula: P1V1=P2V2 P2= (1.25 atm)(2.5L) 2.0L P2 = 1.56atm
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.
The temperature of a gas in 2 L container is 300K.What will be its volume if the temperature is increased to 500K?
.
Now class . we also have a combine Gas Law
It occurs when we consider both Boyles law and Charles Law
P1V1 = P2V2 T1 T2
This is expressed mathematically as: Let’s have a sample problem.
A gas occupies a volume of 3L at 323K and 1.50atmwith a final temperature of . 298K Compute its volume at STP
Given: V1= 2L T1= 300K T2= 500K F: V2 Formula: V1 = V2 T1 T2 2L = V2 300K 500K V2 = 3.33 L
Combined Gas Law states that” for a given mss of gas, the volume is inversely proportional to the pressure and directly proportional 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
Do you have any questions? None, Ma’am 5 min. 6. Application Applications of gas laws are unlimited.
And some are_____
Possible answers:
• OPENING A SODA CAN.
Inside a can or bottle of carbonated soda is carbon dioxide gas (CO 2 ), most of
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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 high-pressure 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.
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
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(Gas Law)
Chemistry Student Teacher
