NATS 101: “The World We Create” • Welcome Back! • Remember Project 2 Due • TODAY! 3/23
Ozone Depletion Acid Rain Global Warming Where Were We? • In Unit 2 we discussed environmental change, including natural and man-made effects. • We talked about how some of the substances we put into the atmosphere are negatively affecting our environment.
Unit 3:New materials,to build or to waste? Today we start Unit 3! Let’s talk about how we are positively impacting our environment
Power Generation • Used to fuel many things, from cars, to furnaces, to electricity generation.84% Petroleum use • Materials SynthesisUsed to make a variety of products/materials • 16% Petroleum use Petroleum We have seen that petroleum is used primarily for two things:
What are some things made from petroleum? • Plastics • Cosmetics • Fertilizer/ Insecticide • Rubber Products • AND MORE
The Challenge How do you get from this CHEMICAL REACTIONS!! to these?
Today’s Expected Outcomes • Recognize and describe the characteristics of a chemical reaction; • Describe and follow the necessary steps to synthesize a useful product; • Recognize materials that have positively impacted our environment.
Chemical Reaction? You decide Number your paper 1-10. Designate whether the situation describes a chemical reaction(True) or does not (False) 1. Rubbing alcohol evaporating from surface of your skin 2. Burning a candle 3. Melting a sugar cube 4. Cooking an egg 5. Freezing water (liquid water turning to ice) 6. A photographer’s flash blub flashing 7. Leaving a wagon outside to rust 8. Accidentally spilling bleach on your favorite jeans 9. Taking a few TUMS after a particularly spicy dinner 10. Butter melting on warm toast Keep your paper, we will revisit these at the end of class.
Chemical Reaction? You decide Let’s examine a few more examples; jot down some quick notes: Videos: Reaction or No Reaction? What is happening in the video? What does the process start with and what does it end with? Does this represent a chemical reaction? Why or why not?
What is a Chemical Reaction? Use information and rules you used to distinguish chemical reactions from non-reactions in the True/False activity, as well as the information you’ve gathered from the videos to answer this question. Discuss your ideas with your teammates . . . Think about . . . How you decided what was truly a chemical reaction and what was not? What characterizes a chemical reaction?
Chemical Reactions: Definition -A shuffling or rearrangement of chemical building blocks (atoms) -Leads to the formation of products that have different properties than the reactants used to create them. Reactants: all substances that react during the change Products: all substances produced after the change
Chemical Reactions: Representation Ball and Stick Models Space Filling Models Words: Magnesium wire + oxygen gas magnesium oxide Letters and Symbols 2Mg(s) + O2(g) 2MgO(s)
Chemical Reactions: RepresentationSome important facts to consider • Atoms are not created or destroyed in a chemical reaction; molecules may be broken apart and recombined to form new molecules • The molecules on either side of a reaction arrow may not be the same (nor do they have to be) * All atoms on one side of the equation must be equal to those on the other, the same number of each type of atom must appear on both sides of the equation 2 Mg(s) + O2(g) 2 MgO(s)
Chemical Reactions: A Closer Look AgNO3(aq) +KCl(aq) AgCl(s)+KNO3(aq) Can you describe what is happening in this reaction? Can you detect a pattern? Displacement Reaction: reactants change partners to create new products
- - What happens when we mix them? + + - - + + + + - - A Closer Look:Displacement Reactions AgNO3(aq) +KCl(aq) AgCl(s)+KNO3(aq) Who are the players? Ag+, (NO3)- , K+, Cl-
- - - - + + + + - - + + + + - - Displacement Reactions AgNO3(aq) +KCl(aq) AgCl(s)+KNO3(aq) How do they change partners? + KNO3 (aq) AgCl(s) AgNO3(aq) +KCl(aq) In General: MN +PQ MQ + PN
Let’s Examine: Displacement Reactions • Follow the directions on the handout in order to experiment with displacement reactions. • Be sure to record: • Observations of the reactants before you combine them, and products after you combine them (i.e. what do they look like) • The chemical formulas of the reactants you are combining. • Attempt to write the full chemical equation of each reaction **Remember in a displacement reaction: MN + PQ MQ + PN
PRECIPITATES Results: What did you see? A+B:K2CO3(aq) + K3PO4(aq) K3PO4(aq)+ K2CO3(aq) (clear liquid) (clear liquid) (clear liquid) A+C:K2CO3(aq) + CuCl2(aq) 2 KCl(aq) + CuCO3(s) (clear liquid) (blue liquid) (blue solid) A+D:K2CO3(aq) + CoCl2(aq) 2 KCl (aq) + CoCO3(s) (clear liquid) (red liquid) (purple solid)
Results: What did you see? B+C: 2K3PO4(aq) + 3CuCl2(aq) 6KCl (aq) + Cu3(PO4)2(s) (clear liquid) (blue liquid) (dark blue solid) B+D:2K3PO4(aq) + 3CoCl2(aq) 6KCl(aq) + Co3(PO4)2(s) (clear liquid) (red liquid) (dark blue solid) C+D:CuCl2(aq) + CoCl2(aq) CuCl2(aq) + CoCl2(aq) (blue liquid) (red liquid) (gray liquid)
How do we know there was a chemical reaction? • Color change • Formation of a precipitate: an insoluble product • Energy is released (in the form of heat, light, etc. we have seen these is the past, do you remember what they are called?) Based on our results and all of the reactions we have seen, how do we know a chemical reaction has happened? We often see the effects of a chemical reactions in the difference between the reactants and products.
Final Component of Chemical Reactions We were able to merely combine reactants and observe a reaction, this isn’t always the case. Can you think of any reason why not? Necessary Conditions . . . Temperature: more energy in the system = more collisions* Pressure: more pressure mean less space for molecules to move around = more collisions Concentration: more molecules to react = more collisions Presence of a Catalyst: a compound that in some way effects the progress of a chemical reaction, without being changed or consumed in the reaction All of these are components of a set of carefully controlled conditions, required to effectively generate the desired products, and are collectively called Reaction Conditions
Creation of New Materials Scientist manipulate the products of chemical reactions (usually many reactions in many steps) to create useful products. Scientists use what they know about chemical reactions, reactants and products to design and synthesize products to meet particular needs.
New Materials We can break the creation of new materials into 3 steps: Let’s examine these 3 ideas in terms of the precipitate we made in the previous displacement reactions. K2CO3(aq) + CoCl2(aq) 2 KCl(aq) + CoCO3(s) (clear liquid) (red liquid) (purple solid) Design Synthesis Processing We’ve created a pigment that can be used to color many different materials
New Materials: Design When designing new materials what considerations might scientists need to think about? Objectives: What are we trying to make, what purposes do we need to accomplish, yield, product purity Limitations: Costs (equipment and raw materials), space, safety, environmental impact, reliability (of equipment and process), flexibility (in design and process) What could we make with our pigment?
New Materials: Synthesis What do we mean by the word synthesis? In terms of synthesis, what might scientists need to think about when creating new materials? Scientists often consider. . . -the specific reactants and sequences of reactions that can be utilized in order to create the desired products -the best set of reaction conditions to maximize the yield. We’ve already synthesized the pigment K2CO3 + CoCl2 CoCO3 + 2KCl
New Materials: Processing What additional steps need to be accomplished in order to create a useful product? Products must often be: - separated (i.e. centrifugation) - filtered - distilled - purified - combined with additional materials • What about our Pigment? • Separate out of solution • Transform it from a powder to a useful product
Creating a Product: It’s your turn! You and your group members are going to become chemical engineers You must process this pigment, in order to create a useful paint product. Directions: Each group of 3 students will receive the following supplies: • 1 gram of pigment (CoCO3) • 1 small vial of Linseed Oil (solvent) • 1 mL pipette (for measuring the oil) • 1 plastic teaspoon (for measuring the pigment) • “Paintbrush” to test your paint • 1 plate to perform experiments on
Creating a Product: It’s your turn YOUR TASK: Using these supplies, work with your group to determine the ratio of pigment to oil that yields the “best” paint. Be Prepared to: • Define what “best” means to your group; (i.e. dries the fastest, has the deepest color, etc.) • Share your recipe for the best paint
What did you produce? • What was your best product? • What was the recipe for that product? You’ve taken raw materials (pigment) and transformed them into paint, what are some other materials that have transformed your world?
Drastic Transformations:Materials that have changed our world • Medication/Pharmaceuticals • Agrochemicals • Plastics and Elastomers (You’ll learn more about these on Thursday!) • Fuels • Detergents (soaps, shampoos, cleaners) • Flavorings
Chemical Reaction?: You decideLet’s revisit our list Number your paper 1-10. Designate whether the situation describes a chemical reaction (True) or does not (False) 1. Rubbing alcohol evaporating from surface of your skin 2. Burning a candle 3. Melting a sugar cube 4. Cooking an egg 5. Freezing water (liquid water turning to ice) 6. A photographer’s flash blub flashing 7. Leaving a wagon outside to rust 8. Accidentally spilling bleach on your favorite jeans 9. Taking a few TUMS after a particularly spicy dinner 10. Butter melting on warm toast False True False True False True True True True False