1. 180 170 160 150 140130120 110100 90 80 7060504030 20 1098765432 1 0 Seconds Remaining: Many chemical reactions occur around the home. – Describe one chemical reaction that occurs in a home and the products of the reaction.

2. A chemical reaction that occurs around the home is the burning of charcoal for barbecues. When charcoal burns, it reacts with oxygen to form ash, carbon dioxide, and heat. The cooking of food is another example.

3. 180 170 160 150 140130120 110100 90 80 7060504030 20 1098765432 1 0 Seconds Remaining: Copper sulfate, when dissolved in water, has a blue color. When steel wool is mixed with a copper sulfate solution, the steel wool disappears, a brownish solid forms, and the color of the solution changes from blue to green. – Explain how three changes that occur in this experiment suggest a new substance may have been formed.

4. The disappearance of the steel wool suggests that a new substance is forming. As steel does not dissolve in water, it is likely that it was part of the reaction that formed a new substance. Another new substance, the brown solid, was observed forming. Because it is different in color from the other substances, it is also probably a new substance. The color change of the solution from blue to green implies that a chemical change has taken place.

5. 180 170 160 150 140130120 110100 90 80 7060504030 20 1098765432 1 0 Seconds left: List the four signs of a chemical reaction

6. 1.Formation of a gas 2.Formation of a precipitate (solid in a liquid) 3.Color change 4.Energy change

7. 180 170 160 150 140130120 110100 90 80 7060504030 20 1098765432 1 0 Seconds Remaining: Describe the difference between ionic and covalent bonding.

8. Ionic bonding is the gaining or losing of electrons in atoms to make happy atoms. Covalent bonding is the sharing of electrons between atoms to make happy atoms.

9. 180 170 160 150 140130120 110100 90 80 7060504030 20 1098765432 1 0 SECONDS REMAINING: What happens to atoms during a chemical reaction?

10. Chemical reactions occur when different atoms and molecules combine together and spit apart. Atoms are re-arranged in the way they are connected (or bonded); they are not created or destroyed.

11. 180 170 160 150 140130120 110100 90 80 7060504030 20 1098765432 1 0 SECONDS REMAINING: Explain the difference between chemical and physical changes.

12. PHYSICAL REACTION – is a change that affects the size, shape or color of a substance but does not affect its composition – no new substance is formed Examples might by melting, boiling, cutting, etc. CHEMICAL REACTION – is a change caused by the rearrangement of the atoms of one or more substances, resulting in the formation of new substances, having entirely different properties.

13. 180 170 160 150 140130120 110100 90 80 7060504030 20 1098765432 1 0 Seconds Remaining: State the Law of Conservation of Mass

14. Matter cannot be created or destroyed in an ordinary chemical reaction.

15. 180 170 160 150 140130120 110100 90 80 7060504030 20 1098765432 1 0 Seconds Remaining: Describe endothermic and exothermic

16. Endothermic – absorbing energy Exothermic – releasing energy

17. 180 170 160 150 140130120 110100 90 80 7060504030 20 1098765432 1 0 Seconds Remaining: A student wrote the following equation: 4Al + 3O 2 2Al 2 O 3 – Write a sentence to describe what occurs in this reaction.

18. In this reaction, aluminum reacts with oxygen to form Al 2 O 3.

19. 180 170 160 150 140130120 110100 90 80 7060504030 20 1098765432 1 0 Seconds Left: Students carry out a chemical reaction by mixing two solutions in a glass beaker. A temperature probe in the beaker records changes in temperature that occur after mixing. Within seconds after mixing, the temperature rises from 25 °C to 40 °C. Then the temperature returns to 25 °C over a period of several minutes. –Based on this data, what should be concluded about the type of chemical reaction that has occurred?

20. The best conclusion is that an exothermic reaction has occurred. The students observe the temperature rising by 15 °C soon after they mix the chemicals. This shows that the reaction has given off energy as heat. Although there is cooling afterward, that is normal. Any hot object cools as it gives off heat.

21. 180 170 160 150 140130120 110100 90 80 7060504030 20 1098765432 1 0 Time Remaining: Betsy mixes and stirs two chemical solids together. While stirring she notices that the beaker is getting hot. What is happening to the beaker?

22. The reaction of the two chemicals is releasing heat – an EXOTHERMIC reaction