Using barometric pressure to teach about particle motion and states of matter
In a few simple experiments, temperature can be related to the the kinetic energy of particles inside a substance, or the the transfer of thermal energy from one object to another through kinetic energy in order to teach NGSS MS-PS1-4. In doing these experiments, students can gain an understanding of how particle motion is affected when thermal energy is added or removed. This can also be related to the changes of state of a substance as a solid, liquid, or gas.
NGSS MS-PS1-4 specifically states:
Develop a model that predicts and describes changes in particle motion, temperature, and state of pure substance when thermal energy is added or removed.
Understanding NGSS MS-PS1-4 through gas laws
Gay-Lussac’s Law - Temperature and pressure are directly proportional
The most directly connected lesson on the PocketLab Educator page is listed as lesson 1 in the links below. However, the other activities also can help students develop a qualitative model of what is happening in a substance on a molecular level. Most of the experiments involve measuring the barometric pressure of a gas in a sealed container. Students then add thermal energy to the container and observe the change in pressure. The added thermal energy will increase the kinetic energy of the particles in the gas, causing an increase in barometric pressure. As more heat is added, the pressure increases proportionally. Students can then work to develop a model that can predict the pressure of the gas given certain temperatures. Gay-Lussacs Law is the gas law that shows that the temperature and pressure of a gas are directly proportional.
Boyle’s Law - Volume and pressure and inversely proportional
In other related activities, students can change the volume of the gas to see how the pressure changes. This does not directly align with NGSS MS-PS1-4 as students aren’t adding thermal energy. However, as they see how the pressure increases and decreases with changes in volume, it will help them think about what is happening with the particles in the gas. If the volume of the sealed container is decreased, the kinetic energy of the particles does not change, yet the pressure increases. Students can design and develop models by drawing diagrams to show why this occurs. Designng and Developing Models is the Science and Engineering Practice in NGSS MS-PS1-4.
Understanding NGSS MS-PS1-4 through Energy Transfer
Another related activity is also a great way to get students up and moving, exerting their own energy. In lesson 6 in the lesson links, students use a temperature probe to measure the change in thermal energy of a jar of sand. They can “add” thermal energy to the sand through kinetic energy (shaking the jar of sand). The longer and more vigorously they shake the sand, the greater the kinetic energy of the grains of sand and therefore the greater the thermal energy. This can be used as an experiment to show how kinetic energy and thermal energy are related. While the grains of sand are obviously larger than individual molecules, they can in some ways model particle motion for the students so it is less abstract. The more the sand is moving, the more kinetic energy it has, and therefore, the more thermal energy it has. Similarly, when thinking about NGSS MS-PS1-4, when thermal energy is added to a substance like liquid water, the particles gain kinetic energy, moving around more and more until they eventually transfer the state of the liquid water to gas.
Science and Engineering Practices in NGSS MS-PS1-4
The Science and Engineering practices in NGSS MS-PS1-4 ask students to develop a model tp predict and/or describe phenomena, In this case, the phenomena they need to describe is how particle motion relates to thermal energy. In the first lesson link below, students create a model of the phenomena by using the evidence they collected to draw diagrams of the particle motion fo the gas at different temperatures. In the second lesson linked below (and as an extension in the first lesson), students create a model by graphing pressure versus temperature data. They can then use that graph to predict pressure changes at different temperature.
- Investigating Thermal Energy and Particle Motion
- Investigating Gay-Lussac’s Law and Absolute Zero of Temperature
- Investigating Boyle’s Law
- Pressure and Volume with a Syringe
- Pressure and Volume with a Syringe and Flask
- Energy Conservation - Transferring Kinetic Energy to Thermal Energy
For lesson 6
Container for sand (disposable coffee cups with lid works well)
Summary of NGSS Alignment for NGSS MS-PS1-4
NGSS MS-PS1-4 Performance Expectation:
Develop a model that predicts and describes changes in particle motion, temperature, and state of pure substance when thermal energy is added or removed. (Clarification Statement: Emphasis is on qualitative molecular-level models of solids, liquids, and gases to show that adding or removing thermal energy increases or decreases kinetic energy or the particles until a change of state occurs. Examples of models could include drawing and diagrams. Examples of particles could include molecules or inert atoms. Examples of pure substances include water, carbon dioxide, and helium).
Science and Engineering Practices
Developing and Using Models Modeling in 6–8 builds on K–5 and progresses to developing, using and revising models to describe, test, and predict more abstract phenomena and design systems.
- Develop a model to predict and/or describe phenomena.
Disciplinary Core Ideas
PS1.A: Structure and Properties of Matter
- Gases and liquids are made of molecules or inert atoms that are moving about relative to each other.
- In a liquid, the molecules are constantly in contact with others; in a gas, they are widely spaced except when they happen to collide. In a solid, atoms are closely spaced and may vibrate in position but do not change relative locations.
- The changes of state that occur with variations in temperature or pressure can be described and predicted using these models of matter.
PS3.A: Definitions of Energy
- The term “heat” as used in everyday language refers both to thermal energy (the motion of atoms or molecules within a substance) and the transfer of that thermal energy from one object to another. In science, heat is used only for this second meaning; it refers to the energy transferred due to the temperature difference between two objects. (secondary)
- The temperature of a system is proportional to the average internal kinetic energy and potential energy per atom or molecule (whichever is the appropriate building block for the system’s material). The details of that relationship depend on the type of atom or molecule and the interactions among the atoms in the material. Temperature is not a direct measure of a system's total thermal energy. The total thermal energy (sometimes called the total internal energy) of a system depends jointly on the temperature, the total number of atoms in the system, and the state of the material. (secondary)
Cause and Effect
- Cause and effect relationships may be used to predict phenomena in natural or designed systems.