Colegio de la Purisima Concepcion The Catholic School of the Archdiocese of Capiz Roxas City Junior High School Department
DETAILED LESSON PLAN IN SCIENCE 10 I. Objectives At the end of the lesson, the students are expected to: 1. Transform the ideal gas law into an equation; 2. Calculate the universal gas constant to derive its constant value; and 3. Value the importance of the ideal gas law in real life application. II. Subject Matter A. Topic: The Ideal Gas Law B. References: Science for the 21st Century Learner 10, pp. 316-318 C. Materials: Projector, PowerPoint Presentation, Laptop, Board work D. Value Focus: Appreciation, patience in solving scientific problems III. Procedure TEACHER’S ACTIVITY A. Introduction/Preliminary Activities
STUDENT’S ACTIVITY
Greetings and Prayer “Good Morning, Class”
“Good Morning, Sir” (One student will lead the prayer.)
Review “As we already knew from Avogadro’s law, the volume of a gas is directly proportional to the amount of gas at a constant temperature and pressure.” behind
the “The man behind the Avogadro’s law is Amadeo Avogadro.”
hypothesize
his “He hypothesized that at a constant temperature and pressure, the volume occupied by a gas is proportional to the number of gas particles.”
“Who is that man Avogadro’s law?” “Very good.” “How did he experiment?”
“That was great.” B. Motivation “Have you experience riding in an “Yes Sir.” airplane?” “How does it feel?”
“I felt comfortable and a little bit nervous.” “I felt some pain in my ear.”
“Don’t you know that there is an “No Sir.” estimation of cabin pressurization in an airplane?”
“And if you don’t know let’s have to discover and know more about that this morning.” C. Lesson Proper Introduction “We have already identified the existing relationships between absolute temperature (T), pressure (P), volume (V) and the number of moles (n) through the different gas laws.”
Presentation of the Lesson “Ideal gases as described by the (The students will listen attentively and raise kinetic molecular theory are those their hands if there is a question.) whose particles have negligible volume and exert no attraction between one another. These relationships between the gas laws can be combined and manipulated to form a more general description and equation that relate volume, pressure, temperature and amount of gas.” “Can you summarized the equation of : BOYLE’S LAW
V
1 , at constant n, T P
CHARLE’S LAW
V
T, at constant n, P
V
n, at constant P, T
AVOGADRO’S LAW” “Very good.” In order to combined these separate relationship we can have: V nT P Because these variables are all related, we can introduce a constant to express it into an equivalent equation: V = constant x nT P The constant in this equation is known as the ideal gas constant. This is usually represented with the symbol R. Substituting the symbol R in the previous equation will give you: V = RnT P
Because pressure is inversely proportional to volume, it will be place on the left side and the equation can be rewritten as: PV = nRT The relationships among the absolute temperature, amount of gas particles, volume and pressure can be observed in the ideal gas equation. Because R is a constant, it does not change value when the other variables change. “How can we derive the value for R?” “The numerical value for R can be calculated by substituting the STP conditions for one “In order to obtain the numerical mole of an ideal gas.” value of R it can be calculated by substituting the STP conditions for one mole of an ideal gas and from the Ideal Gas Formula we can solve for: R = PV nT R = (1atm) (22.4L) (1mol) (273K) = 0.0821 L-atm mol-K “This constant is only valid if you express volume in liters and pressure in atmosphere (atm). You will have to convert the given values to appropriate unit(s) to be able to use this constant.” “Any question class?” Sample Problem: “No, Sir.” Determine how many moles of nitrogen dioxide (NO2) are present in a 3.0L container at a temperature Solution: of 25.0°C and a pressure of 650 torrs? T = 25.0°C = 298K V = 3.0L P = 650 torr = 0.86atm n=? Use equation 8.9 found in your textbook to determine the number of moles present in the container. Rearrange the equation To come up with an equation for n.
PV = nRT n = PV RT = (0.86 atm)(3.0 L) (0.0821 L-atm)(298K) mol-K n = 0.11 mol D. Generalization “What are the measurable “The measurable properties that are involved properties of gases that are involved in the ideal gas law are temperature, pressure, in the ideal gas law?” volume and the number of moles.” “What is the letter that denotes the “Letter R” constant in the equation of the ideal gas constant?” “How can the numerical value of R “The numerical value of R can be calculated be calculated?” by substituting the STP conditions for one mole of an ideal gas.” E. Application (Problem Solving) What is the volume of 0.90 mol of Given: He at a temperature of 45.0°C and a V = ? T = 45.0°C = 318K pressure of 350 torr? n = 0.90 mol P = 355 torr = 0.47atm V = nRT P = (0.90 mol)(0.0821 L-atm/mol-K)(318K) 0.47 atm V = 49.99 L or 50.0L IV. Evaluation (Quiz) Calculate the following: 1. A sample of argon gas at STP occupies 56.2 liters. Determine the number of moles of argon in the sample. 2. At what temperature will 0.654 moles of neon gas occupy 12.30 liters at 1.95 atmospheres? V. Assignment Cite a real life situation where the Ideal Gas Law is applied. Prepared by: CRISTIAN V. CAPAPAS Student Teacher
Checked by: MRS. ELENA F. FRIO
Cooperating Teacher
