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Le Chatelier's Principle

The students explain their examples of real world chemical equilibrium, including in our bodies. The teacher demonstrates Le Chatelier's principle using a solution of tea, showing how different additives will change the tea's color and its equilibrium. The students prepare to do an experiment concerning the equilibrium of smog.

The students explain their examples of real world chemical equilibrium, including in our bodies. The teacher demonstrates Le Chatelier's principle using a solution of tea, showing how different additives will change the tea's color and its equilibrium. The students prepare to do an experiment concerning the equilibrium of smog.

Premiere Date: August 16, 2016 | Runtime: 00:20:12

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Unit 10D Note Taking Guide & Segment Questions
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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.

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

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)

Constructing Explanations and Designing Solutions

The goal of science is the construction of theories that provide explanatory accounts of the world. A theory becomes accepted when it has multiple lines of empirical evidence and greater explanatory power of phenomena than previous theories.”(NRC Framework, 2012, p. 52)

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)

Vocabulary

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

SC2Obtain, evaluate, and communicate information about the chemical and physical properties of matter resulting from the ability of atoms to form bonds.

SC2.gDevelop a model to illustrate the release or absorption of energy (endothermic or exothermic) from a chemical reaction system depends upon the changes in total bond energy.

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.)

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