Algebra 2 p.84 Glencoe/McGraw Hill
Chemistry 1996 D.C. Heath pp. 228-241
Chemistry: Connections to Our Changing World
Prentice-Hall pp. 439-442
|Using prior knowledge concerning the gas laws, lab skills and techniques, the student will design an experiment to measure the molar mass of the gas found inside a disposable lighter.|
SI-H-A1-A7 2 - 3 class periods
PS-H-A1-A4, C3, C7
procedures -mole concept
-Massing using 0.001 g -Gas Laws including Ideal Gas
digital or centigram balance -variables for gas laws
-CBL with barometer probe -determining molar mass
-Reading a thermometer - graphic calculator
-Reading a graduated cylinder
-Converting: gas factors
SCIENCE EDUCATION STANDARDS 9-12
1) Science as Inquiry Content Standard A: Understanding about Scientific Inquiry
2) Physical Science Content Standard B: Structure & Properties of Matter 2,4
3) Science & Technology Content Standard E: Abilities of Technology Design
Hold up a lighter and ask the following questions…waiting for student responses.
1) We have a ____? lighter
2) What is in the lighter? Butane
3) Is it a gas? Yes
(Have BUTANE written on the board)
1) What is the molar mass of this gas? (give students time to calculate) 58.14g/mol
2) What is the ideal gas law? PV=nRT
possible variables? P, V, n, T
constant ? R
3) What is Dalton's Law of Partial Pressure??
Working in groups of 4, design an experiment to measure the molar mass of this gas. Utilize class time today to develop procedures, determine and procure materials and equipment, and research water vapor pressure (if needed).
Determine variables, constants and conversion factors needed.
Tomorrow, actual discovery with data collection. (Teacher monitor and assist as needed.
(Review, clarify and assist as needed) Monitor lab procedures. Data collection will not take long. Students will complete calculations of molar mass using formula:
n = RT Have water vapor pressure tables and barometer readings from weather station and CBL barometer probe.
Pose questions on Analysis and Extension sheets (attached).
One possible assessment tool is attached. Can be used for both days.
Teacher could also add bonus points, if desired.
As a group, design an experiment to measure the molar mass of the gas in the lighter. The group will utilize prior knowledge concerning gas laws, lab skills and equipment. State a hypothesis, the problem, procedures, SAFETY, materials and equipment. Determine and locate the variables utilized in your calculations upon completion of the data collection.
The discovery will be completed during the next class meeting.
c) MATERIALS AND EQUIPMENT:
a) Compare and contrast actual to theoretical values.
b) Evaluate the pressure (was it at or below 1 atm?)
c) Do gases behave "ideally?" Support your answer.
d) Can this data
be utilized to determine the Avogadro Constant?
molar volume = volume of gas collected at STP
number moles gas collected
a)Find the volume of a hypothetical cylinder occupied by one butane molecule. Assume that the molecule has a diameter of 4.5 x 10-8 cm and travels the mean free path distance of 1.0 x 10-4 cm/molecule.
Volume of cylinder =
b) Find the Avogadro constant.
Volume of cylinder
GROUP OF 4 :
a) Identified the problem
b) Stated a hypothesis
c) Identified constants
d) Listed materials and equipment
e) Designed procedures
f) Executed a plan
g) Applied process and problem solving
h) Reached a reasonable conclusion
i) Demonstrated group effort
GROUP OF 2:
10 Implemented procedures
3 Collected data
30 Calculations, Analysis, Extension