Unit 2 topic 7

Question 1

What is one important thing to remember in a chemical reaction?

Answer 1

the properties of the new substance are different from the original substances.

Question 2

what are the following signs that you know a chemical change has occurred?

Answer 2

Color
Odor
Temperature
gas(bubbles) 
precipitate or light is produced

Question 3

is a change a chemical change

Answer 3

no

Question 4

what are important things to remember about chemical bonds

Answer 4

chemical bonds need to be broken down and new ones are formed in chemical reactions
- since energy is stored in chemical bonds all chemical reactions involve changes in enegry.

Question 5

what is an example of exothermic reactions

Answer 5

(heat, or light) Explotions, or combustions

Question 6

What are examples of endothermic reactions

Answer 6

(Heat, sunlight) electrolysis of water, cold packs

Question 7

what is an example of breaking down something in a chemical reaction

Answer 7

when baking soda is mixed into some kinds of cookie dough, the baking soda absorbs enrgy and breaks down the water.

Question 8

We know that atoms are neither lost nor created in a chemcial change what is one more key thing about atoms

Answer 8

atoms just change partners as old substances are changed into new substances during a chemcial reaction