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Chemical Equilibrium

Our host introduces equilibrium theories and the dynamic nature of chemical equilibrium. The students perform an activity using Legos® to understand the nature of how forward and reverse reactions affect equilibrium and the amount of products and reactants in a reaction.

Our host introduces equilibrium theories and the dynamic nature of chemical equilibrium. The students perform an activity using Legos® to understand the nature of how forward and reverse reactions affect equilibrium and the amount of products and reactants in a reaction.

Premiere Date: August 16, 2016 | Runtime: 00:18:55

Support Materials


Lego® Lab
Unit 10A Note Taking Guide & Segment Questions

Crosscutting Concepts

System and System Models

Defining the system under study—specifying its boundaries and making explicit a model of that system—provides tools for understanding and testing ideas that are applicable throughout science and engineering.


Observed patterns of forms and events guide organization and classification, and they prompt questions about relationships and the factors that influence them.

Stability and Change

For natural and built systems alike, conditions of stability and determinants of rates of change or evolution of a system are critical elements of study.

Cause and Effect

Mechanism and explanation. Events have causes, sometimes simple, sometimes multifaceted. A major activity of science is investigating and explaining causal relationships and the mechanisms by which they are mediated. Such mechanisms can then be tested across given contexts and used to predict and explain events in new contexts.

Science & Engineering Practices

Analyzing and Interpreting Data

Once collected, data must be presented in a form that can reveal any patterns and relationships and that allows results to be communicated to others. Because raw data as such have little meaning, a major practice of scientists is to organize and interpret data through tabulating, graphing, or statistical analysis. Such analysis can bring out the meaning of data—and their relevance—so that they may be used as evidence.
Engineers, too, make decisions based on evidence that a given design will work; they rarely rely on trial and error. Engineers often analyze a design by creating a model or prototype and collecting extensive data on how it performs, including under extreme conditions. Analysis of this kind of data not only informs design decisions and enables the prediction or assessment of performance but also helps define or clarify problems, determine economic feasibility, evaluate alternatives, and investigate failures. (NRC Framework, 2012, p. 61-62)

Asking Questions and Defining Problems

Students at any grade level should be able to ask questions of each other about the texts they read, the features of the phenomena they observe, and the conclusions they draw from their models or scientific investigations. For engineering, they should ask questions to define the problem to be solved and to elicit ideas that lead to the constraints and specifications for its solution. (NRC Framework 2012, p. 56)

Generating a Hypothesis and Developing a Model

Modeling can begin in the earliest grades, with students’ models progressing from concrete “pictures” and/or physical scale models (e.g., a toy car) to more abstract representations of relevant relationships in later grades, such as a diagram representing forces on a particular object in a system. (NRC Framework, 2012, p. 58)

Planning and Carrying Out Investigations

Students should have opportunities to plan and carry out several different kinds of investigations during their K-12 years. At all levels, they should engage in investigations that range from those structured by the teacher—in order to expose an issue or question that they would be unlikely to explore on their own (e.g., measuring specific properties of materials)— to those that emerge from students’ own questions. (NRC Framework, 2012, p. 61)


chemical equilibrium - a state that is reached when the rate of the forward reaction equals the rate of the reverse reaction.

dynamic equilibrium - a state of equilibrium in which two opposing processes occur simultaneously with no net change. 

equilibrium - a condition in which all acting influences are canceled by others, resulting in a stable, balanced, or unchanging system. 

equilibrium constant (ksubeq) - the ratio of the concentration of products divided by the concentration of reactants. 

Le Chatelier's Principle - a principle that states that when the equilibrium of a system is disturbed or stressed, the system adjusts to reestablish equilibrium by minimizing or countering the stress.

static equilibrum - a state of equilibrium in which no movement occurs.

The Haber Process - the process of synthesizing ammonia from nitrogen and hydrogen gases.


Georgia Standards of Excellence

SC4Obtain, evaluate, and communicate information about how to refine the design of a chemical system by applying engineering principles to manipulate the factors that affect a chemical reaction.

SC4.aPlan and carry out an investigation to provide evidence of the effects of changing concentration, temperature, and pressure on chemical reactions. (Clarification statement: Pressure should not be tested experimentally.)

SC4.bConstruct an argument using collision theory and transition state theory to explain the role of activation energy in chemical reactions. (Clarification statement: Reaction coordinate diagrams could be used to visualize graphically changes in energy (direction flow and quantity) during the progress of a chemical reaction.)

SC4.dRefine the design of a chemical system by altering the conditions that would change forward and reverse rates and the amount of products at equilibrium. (Clarification statement: Emphasis is on the application of LeChatelier’s principle.)

Request Teacher Toolkit

The Chemistry Matters teacher toolkit provides instructions and answer keys for labs, experiments, and assignments for all 12 units of study. GPB offers the teacher toolkit at no cost to Georgia educators. Complete and submit this form to request the teacher toolkit. You only need to submit this form one time to get materials for all 12 units of study.