Homework 6

2009 - 2010

Homework 6: 9/24/09 - 10/1/09

Mr. Sam Harrelson MS Room 312 Email: [email protected] Tel: 864-381-7374 (or 864-381-SDSG) http://griffinscience.com

More information can be found on GriffinScience.com and feel free to email or call me with any questions you might have! Mr. Harrelson -This week, we are studying chemical reactions. This is one of my favorite topics of study because we see how and why elements combine to form the things they do! So, here’s your homework for the week:

Objective 1: Define the Following Terms: 1. Physical Property 2. Chemical Property 3. Physical Change 4. Chemical Reaction 5. Endothermic Reaction 6. Exothermic Reaction 7. Conservation of Mass 8. Coefficient 9. Replacement 10. Activation Energy 11. Concentration 12. Catalyst

Physical Science - Grade 8 - Homework 6

1

2009 - 2010

Homework 5: 9/17/09 - 9/24/09

Objective 2: Chemical Reaction Concepts 1. What are two kinds of changes that occur in matter? Describe how you can tell one from the other. 2. Why can’t you balance a chemical equation by changing the subscripts of the reactants or the products? 3. You find the mass of a piece of iron metal, let it rust, and measure the mass again. The mass has increased. Does this violate the principle of conservation of mass? Explain. 4. Why does spraying water on a fire help to put the fire out? 5. How are inhibitors useful in controlling chemical reactions? Objective 3: Thinking Critically About Chemical Reactions 1. Steel that is exposed to water and salt rusts quickly. If you were a shipbuilder, how would you protect a new ship? 2. When silver coins are found in ancient shipwrecks, they are coated with a black crust. What question could you ask to help you decide whether the silver underwent a chemical change or a physical change? Explain. 3. What are 5 kinds of evidence you can use to determine if a chemical reaction has occurred? 4. How are endothermic and exothermic reactions the same and how are they different? 5. What are 3 types of chemical reactions? Objective 4: Inferring Information About Chemical Reactions 1. In your own words, state the meaning of the principle of conservation of mass. 2. If the total mass of the products of a reaction is 250 g, what was the total mass of the reactants? 3. What is activation energy? 4. What are 4 ways that chemists can control the rates of chemical reactions? Objective 5: Balancing Chemical Equations 1. Fe + HCl -----------> FeCl2 + H2 2. N2 + O2 ----------> N2O5 3. MgO + HBr ----------> MgBr2 + H2O 4. C2H4 +O2 ------------> CO2 + H2O

Physical Science - Grade 8 - Homework 5

2