SC15.CHM.8
Refine the design of a given chemical system to illustrate how LeChâtelier’s principle affects a dynamic chemical equilibrium when subjected to an outside stress (e.g., heating and cooling a saturated sugar- water solution).*
Refine the design of a given chemical system to illustrate how LeChâtelier’s principle affects a dynamic chemical equilibrium when subjected to an outside stress (e.g., heating and cooling a saturated sugar- water solution).*
Unpacked Content
UP:SC15.CHM.8
Vocabulary
- system
- dynamic equilibrium
- stresses
- LeChatelier's principle
- criteria
- constraints
- reversible reaction
- forward/ backward rates
- macroscopic level
- atomic/ molecular level
- claim
- evidence
- reasoning
Knowledge
Students know:
- Various stresses made at the macroscopic level, such as change in temperature, pressure, volume, concentration, affect a chemical system at the molecular level.
- Reaction rates of forward/ backward reactions change with stresses until rates are equal again.
- Forward/ reverse reactions occur at the same rate in dynamic equilibrium, so chemical systems appear stable at macroscopic level.
- The egineering design process is a cycle with no official starting or ending point, and, therefore, can be used repeatedly to refine your work.
Skills
Students are able to:
- Use the engineering design process (ask, imagine, plan, create, improve) to refine a chemical system.
- Refine a solution to a complex real-world problem, based on scientific knowledge, student-generated sources of evidence, prioritized criteria, and tradeoff considerations.
- Construct and revise an explanation based on valid and reliable evidence obtained from a variety of sources (including students' own investigations, models, theories, simulations, and peer review).
- Construct and present arguments supported by empirical evidence and scientific reasoning to support or refute an explanation or a model for a phenomenon or a solution to a problem.
Understanding
Students understand that:
- Much of science deals with constructing explanations of how things change and how they remain stable.
- Solutions to real-world problems can be refined using scientific knowledge, student-generated sources of evidence, prioritized criteria, and tradeoff considerations.
- In many situations, a balance between a reaction and the reverse reaction determines the numbers of all types of molecules present.
- Criteria may need to be broken down into simpler ones and decisions about the priority of certain criteria over others (tradeoffs) may be needed.
Scientific and Engineering Practices
Constructing Explanations and Designing Solutions
Crosscutting Concepts
Stability and Change
