Introduction to Modeling and Chemical Reactions Physical Science Module 4: Lesson 1-5

Chemistry Concepts Physical Properties of matter Color, melting point, boiling point, density, … Can you think of other physical Properties? Chemical Properties of matter Why is Gold and diamond expensive? Why is Hydrogen gas so dangerous? Why does Peroxide bubble when poured on an wound? Is solubility in water a physical or chemical property?

Atoms and Periodic Table Elements are arranged in the Periodic Table according to their atomic number, which determines their chemical properties and chemical reactivity.

Chemical Symbols & Ions Some elements react to give away electrons and some elements react to gain electrons. Examples: Sodium: Na likes to lose an electron to become Na + Silver: Ag loses an electron  Ag + Chlorine: Cl gains an electron  Cl - Oxygen: O likes to gain two electrons  O -2 Copper: Cu can lose 1 or 2 electrons  Cu +1 or Cu +2 Aluminum: Al loses 3 electrons to become Al +3

Ionic Compounds Ionic Compounds are made of positive ions (cations) and negative ions (anions) held tightly together. When (inorganic) ionic compounds dissolve in water, they separate into their positive and negative ions. States of matter: solid, liquid, gas. Matter that dissolves in water has Aqueous state, and we have a solution.

Examples of Ionic Compounds NaCl (Table Salt) in water: Saline solution AgCl: silver nitrate CuCl 2 : Copper Chloride Al 2 O 3 : aluminum Oxide AgCl (s) in water  AgCl (aq)  Ag +1 (aq) + Cl - (aq)

Video or Live Demonstration Aqueous Silver Nitrate and solid Copper reaction Signs of a chemical reaction:  Color change  Formation of gas: bubbles or funny odor  Formation of precipitate  Change of temperature

StarLogo Nova Base Model Water Molecules setup Silver Nitrate setup Copper rod Setup Why 200 steps? Would 150 steps be enough?

Running the Model: Simulation What signs of a chemical reaction do you see in this simulation? Assumptions (Abstractions) in this model?

Physical Science Lesson 2: Modeling Chemical Reactions

Student Activity #1 Analyzing the Model  Use Model Observation Form  Download the StarLogo Nova Base model: “silver nitrate and copper reaction”  Remix and rename  Run the model and have fun analyzing

Student Activity #2 Use the Student Activity Sheet Challenge 1: Modify the model to add or remove some or all of the water molecules in the model. Challenge 2: Modify the code to move the copper rod somewhere else in the solution keeping the number of agents of copper the same.

Physical Science Lesson 3: Products of Chemical Reactions

Chemistry Concepts Observed behavior Aqueous silver nitrate added to solid copper will react to form aqueous copper nitrate and solid silver. Chemical Reaction 2 AgNO 3 (aq) + Cu (s)  Cu(NO 3 ) 2 (aq) + 2 Ag (s) Reactants  Products Balancing chemical equations Limiting reactant and reactant in excess

Computer Science Concepts Agents represented by breeds. Default breed in StarLogo Nova is “Turtle”. Breeds can be added and can be renamed. What is missing from the model?

Computer Science Concepts What is missing from the model? 2 AgNO 3 (aq) + Cu (s)  Cu(NO 3 ) 2 (aq) + 2 Ag (s) Reactants  Products Did we capture all of the reactants and products in our model? Does our model accurately represent the conservation of mass?

Student Activity #1 Remix and Rename the StarLogo Nova base model: “silver nitrate and copper reaction” Use Student Activity Sheet for guidelines. Challenge: Change the code to add copper nitrate agents to represent the missing chemical product from the model.

Student Activity #2: Experiment Start with the your modified model. Use Experimental Design Form.  Challenge: Run experiment at different initial quantities of copper or silver nitrate and get the amount of silver produced.  How much silver is produced in each case?  Which is the limiting reactant and reactant in excess in each case?

Physical Science Lesson 4: Complex Ions in Solution

Ions in water  Silver nitrate, Ag(NO 3 ) in water dissociates to one ion of Ag + and one ion of (NO 3 ) -. Ag(NO 3 ) (s) in water  Ag + (aq) + NO 3 - (aq)  Copper nitrate, Cu(NO 3 ) 2, is an ionic compound that is soluble in water. In water, it dissociates to Cu +2 [or Cu(II)] and two (NO 3 ) - ions. Cu(NO 3 ) 2 (aq)  Cu +2 (aq) + 2 (NO 3 ) - (aq)

Complex Ions  Copper ions [Cu +2 [or Cu(II)] in water form a complex ion with 3 water molecule which produces the blue hue in the solution. This complex can be referred to as Copper Nitrate.3H 2 O or Cu(II).3H 2 O Note: NO 3 - is a complex negative ion but it a spectator ion in this reaction Ionic Reaction: 2 Ag + (aq) + 2 NO 3 - (aq) + Cu (s) ---> Cu 2+ (aq) + 2 NO 3 - (aq) + 2 Ag (s)

Student Activity #1 Copper nitrate in water forms a complex with 3 water molecules, turning solution blue. Challenge: Change the code to create additional breeds Cu(II).H 2 O Cu(II).2H 2 OCu(II).3H 2 O  Start with StarLogo Nova modified model from Lesson 3. Remix and Rename.  Use Student Activity Sheet for guidance. Execute your model every time you add a piece of code. Debug if needed. Save often.

Rate of a Reaction Increasing the temperature increases the rate of the reaction because the kinetic energy of the reactants increases. Rate of reaction is determined by how fast the reactants are used up or products formed over time.

Physical Science Lesson 5: Impacts on rate of reaction

Model Abstraction: Mixing In the model, we can change the mixing of ions in solution by altering the Wiggle Walk. Change the maximum number of degrees turned in the left and right turn commands. See the impact of changing how agents move.

Model Abstraction: Kinetic Energy In the model, we can change the number of forward steps from 1 to 2 to 3, to mimic the kinetic energy of ions and molecules.

Student Activity #2: Experiment Challenge: Run experiment at different kinetic energy levels OR different mixing and measure time when half of the copper is used up.  Make sure the initial amount of copper and silver nitrate is the same throughout the experiment.  Change the number of forward steps from 1 to 2 to 3 for each experiment OR change the maximum turn radius. Measure Time when half the reaction occurred.  Multiple trials are needed at every different setting of initial amounts used, at each experiment.

Presentations and Reflections