Chemical Reactions Simulation Practice balancing chemical reactions Learning Objectives Understand how to balance chemical reactions A. Definitions Using your online text references (for example sections 4.1 and 4.2), complete the following: 1. Define the terms: chemical equation, reactants, products, and coefficients. 2. State, and then explain in your own words, the law of conservation of matter. 3. What does it mean for a chemical equation to be balanced? 4. What are phase labels? (What does the term “phase" mean?) B. PhET Simulation, Balancing chemical reactions Launch the PhET simulation on balancing chemical reactions and click on the introduction sim. 1. The first reaction, synthesis of ammonia, should be active. In your notebook write the unbalanced (aka skeleton) reaction. 2. Increase the number of ammonia molecules produced to two and count how many total nitrogen and hydrogen atoms show up. What coefficients are needed in front of the hydrogen and nitrogen reactants to balance this equation? 3. Write the most simplified version of the balanced reaction for the formation of ammonia. 4. Explore the tools available in the top right corner. Which one do you prefer and why? 5. Balance and write reactions for the separation of water starting with a. 2 molecules of water b. 4 molecules of water 6. C. 6 molecules of water Can you balance a reaction using this sim for only one molecule of water? Explain. 7. Why doesn't the simulation let you change the subscripts of the molecules? 8. What is the balanced reaction for the combustion of methane? 9. Change the simulation to the game. Complete and write 5 additional reactions. C. Turning equalities into factors or ratios Example Ratio Invert it Scale it up 1 person has 2 legs 1 person 2 legs 2 legs 1 person How many legs for 3 people? 2legs 3 pers. 6legs 1 person 1 cat has 4 legs 1 pizza has 8 slices 2 people drink 3 gallons 2 people eat 3 cookies 2 dozen people eat 3 dozen cookies 1 person uses 2 pieces of paper 1 dozen people use 2 dozen pieces of paper 1 N2 makes 2 NH3 1 mole N2 makes 2 moles NH3 1 mole Na makes 2 moles NaCl # legs for 3 cats? # slices for 3 pizzas? # for 4 people? # cookies for 4 people? # cookies for 4 doz people? #paper for 3 people? # for 3 doz people # NH3 for 3 N₂ # moles NH3 for 3 moles N2 # moles NaCl for 2 moles Na These last two examples are showing the idea of the mole to mole ratio, also called the mole ratio. Read a little about mole ratios in your online textbook. To complete your lab assignment, write a summary of what you learned regarding the learning objectives. Answer the lab conclusion questions: 1. How do you balance a chemical reaction? 2. What is a mole ratio?