Exploring the Properties of Gases (a.m.) Parent Letter
Dear SEP Families,
Students in Session 3 did a great job recognizing the relationships between two gas variables. The following pairs are directly proportional:
We also discussed the inverse relationship between pressure and volume. This information lead us to explore the ideal gas law (PV = nRT) and we practiced solving problems using this equation.
While we did not go into great detail regarding intermolecular forces, we did talk about the fact that gas particles experience attractive forces when they condense into liquids. Students observed the transformation of various gases into liquids/solids (using liquid nitrogen).
The following real world connections were discussed in class:
In the future, students will certainly work with gas laws and relationships between gas variables in chemistry (and to some extent in physics). The kinetic molecular theory of gases can be helpful as students explain the physical behavior of gases. Understanding more about moles, molar relationships, and stoichiometry will help students to appreciate that a balanced chemical equation verifies the law of conservation of matter. Moreover, conversions from one substance into another in the context of chemical equations are based on the mole ratios between different substances.
Students in Session 3 did a great job recognizing the relationships between two gas variables. The following pairs are directly proportional:
- volume & temperature,
- pressure & temperature,
- pressure & moles,
- volume & moles.
We also discussed the inverse relationship between pressure and volume. This information lead us to explore the ideal gas law (PV = nRT) and we practiced solving problems using this equation.
While we did not go into great detail regarding intermolecular forces, we did talk about the fact that gas particles experience attractive forces when they condense into liquids. Students observed the transformation of various gases into liquids/solids (using liquid nitrogen).
The following real world connections were discussed in class:
- Hot air balloons rise because they are less dense than the surrounding air.
- Liquid nitrogen (-320°F) can be prepared when nitrogen gas is cooled and placed under pressure.
- Rubbing alcohol (or other volatile liquids) feel cool on the skin because evaporation is an endothermic process.
- If hydrogen fuel is used to power a car, the only gas produced in the combustion reaction is water vapor.
- Styrofoam (expanded polystyrene) contains mostly air. This polymer does not bio-degrade with exposure to light or water.
In the future, students will certainly work with gas laws and relationships between gas variables in chemistry (and to some extent in physics). The kinetic molecular theory of gases can be helpful as students explain the physical behavior of gases. Understanding more about moles, molar relationships, and stoichiometry will help students to appreciate that a balanced chemical equation verifies the law of conservation of matter. Moreover, conversions from one substance into another in the context of chemical equations are based on the mole ratios between different substances.
Exploring the Properties of Gases (p.m.) Parent Letter
Dear SEP Families,
Students in Session 3 understood the relationships between two gas variables well. The following pairs are directly proportional:
We also discussed the inverse relationship between pressure and volume.
They did a great job with the applications of ideal gas law, which ties all of the gas variables together in one equation. They determined the molar mass of an unknown gas, based on the variables of mass, pressure, volume, and temperature.
Students were also able to articulate the reasons why gases behave as they do. Here is one example of an explanation of the "drinking bird" toy.
The bird's beak gets wet. As the bird rocks back and forth, the water starts to evaporate on the beak. This causes the bird's head to get colder (due to the absorption of heat from the surroundings). Then this lower temperature causes some of the vapor inside the bird to condense back into a liquid. This will lower the pressure inside the head. This drop in pressure causes the volatile liquid to rise up the tube from the bottom. Once the bird tips over, the liquid runs back down, and the process repeats again.
The following real world connections were discussed in class:
If students take courses in chemistry or physics, they will need to understand the kinetic molecular theory in order to understand the physical and chemical properties of gases. Understanding more about moles, molar relationships, and stoichiometry will help students to appreciate that a balanced chemical equation verifies the law of conservation of matter. Moreover, conversions from one substance into another in the context of chemical equations are based on the mole ratios between different substances. Gas behavior also has connections to chemical concepts, such as thermodynamics, kinetics, acid-base chemistry, and equilibrium
Students in Session 3 understood the relationships between two gas variables well. The following pairs are directly proportional:
- volume & temperature,
- pressure & temperature,
- pressure & moles, and
- volume & moles.
We also discussed the inverse relationship between pressure and volume.
They did a great job with the applications of ideal gas law, which ties all of the gas variables together in one equation. They determined the molar mass of an unknown gas, based on the variables of mass, pressure, volume, and temperature.
Students were also able to articulate the reasons why gases behave as they do. Here is one example of an explanation of the "drinking bird" toy.
The bird's beak gets wet. As the bird rocks back and forth, the water starts to evaporate on the beak. This causes the bird's head to get colder (due to the absorption of heat from the surroundings). Then this lower temperature causes some of the vapor inside the bird to condense back into a liquid. This will lower the pressure inside the head. This drop in pressure causes the volatile liquid to rise up the tube from the bottom. Once the bird tips over, the liquid runs back down, and the process repeats again.
The following real world connections were discussed in class:
- Hot air balloons rise up because they are less dense than the colder air around them.
- A tornado (or a vortex) can occur during periods of atmospheric instability, when warm, moist air masses and cold, dry air masses collide to cause large thunderstorms.
- The maximum height of a vertical straw can only be about 10.3 meters long; you would need to create a perfect vacuum inside the straw to suck up the liquid.
- Liquid nitrogen (-196°C) is cold enough to turn gaseous CO2 into solid CO2 (dry ice). This is called deposition.
- The "bends" (a.k.a. decompression sickness) can happen to scuba divers if they rise too quickly. The solubility of nitrogen gas in the blood decreases rapidly upon ascent.
If students take courses in chemistry or physics, they will need to understand the kinetic molecular theory in order to understand the physical and chemical properties of gases. Understanding more about moles, molar relationships, and stoichiometry will help students to appreciate that a balanced chemical equation verifies the law of conservation of matter. Moreover, conversions from one substance into another in the context of chemical equations are based on the mole ratios between different substances. Gas behavior also has connections to chemical concepts, such as thermodynamics, kinetics, acid-base chemistry, and equilibrium
Resources for Continued Learning
Books that your student might find interesting:
Websites with great information about chemistry:
Thank you for being a part of SEP 2016 Session 3!
- Hands-On Chemistry Activities with Real-Life Applications by Norman Herr and James Cunningham
- Illustrated Guide to Home Chemistry Experiments by Robert Bruce Thompson
- Chemistry for Every Kid: 101 Easy Experiments that Really Work by Janice VanCleave
- Chemistry: A Guided Inquiry by Richard S. Moog and John J. Farrell
Websites with great information about chemistry:
- PhET Interactive Simulations for Chemistry ( https://phet.colorado.edu/en/simulations/category/chemistry )
- ExploreLearning Gizmos for Chemistry (https://www.explorelearning.com/index.cfm?method=cResource.dspResourceExplorer&browse=Science/Grade+9-12/Chemistry# )
- ChemMatters (high school chemistry magazine that demystifies chemistry in people's everyday lives. (https://www.acs.org/content/acs/en/education/resources/highschool/chemmatters.html )
Thank you for being a part of SEP 2016 Session 3!
