Friday April 4th!

Substance	pH
Lemon Juice	2.0
Pure water	7.0
Baking Soda	8.0
Tomato Juice	4.5
Ammonia	12.5

1. According to the chart, baking soda is considered a(n)

a. acid

b. base

c. neutral

d. reaction

2. According to the chart, tomato juice is considered a(n)

a. acid

b. base

c. neutral

d. reaction

3. According to the chart, pure water is considered a(n)

a. acid

b. base

c. neutral

d. density

4. Which substance on the chart is the strongest acid? __________________________

5. Which substance on the chart is the weakest base? __________________________

6. The water in the Arizona Canal is around 5.5.  What should be added to make it neutral like pure water?

a. acid                         b. base

c. more water               d. fish

7. A swimming pool has a pH of 8.0.  The correct pH of a swimming pool is between pH 6.5-7.5.  What should be added to the swimming pool to bring it to the correct ph?

a. an acid

b. a base

c. a neutral substance

d. chlorine

8. A student adds together a solution with a pH of 2.0 and a powder with a pH of 8.0.  The pH of this new mixture would be:

a. acidic

b. pH 10

c. basic

d. neutral

9. Which of the following is an example of oxidation?

a. an ice cream cone melting

b. a piece of fruit browning

c. a slice of bread growing mold

d. the paint on a house peeling

10. Oxidation is the reaction of a substance with which element?

a. sulfur

b. nitrogen

c. oxygen

d. carbon dioxide

Lupe and Jessica conducted an investigation to identify an unknown powder that they found on the cafeteria floor.  They tested four known substances: flour, baking soda, sugar, and baking powder.  They also tested an unknown substance, “Substance X”.  The students mixed each substance with water, vinegar, and iodine.  They recorded their findings below.

Substance	Reaction with Vinegar	Reaction with Iodine	Water
flour	no reaction	turns black	dissolves
baking soda	fizzles	no reaction	dissolves
sugar	no reaction	no reaction	dissolves
baking powder	fizzles	turns black	dissolves

11.  The substance on the cafeteria floor turns black with iodine.   It also bubbles in vinegar.  The substance is:

a. flour

b. baking soda

c. sugar

d. baking powder

12. The bubbling that occurred when baking soda was added to vinegar was evidence that:

a. heat was being released

b. a gas was being released

c. heat was being absorbed

d. a color change was occurring

13. The fact that the flour turned black when mixed with iodine is evidence that:

a. a physical change occurred

b. a solubility reaction occurred

c. a corrosion reaction occurred

d. a chemical change occurred

14. The students find another mystery powder.  They test this powder and find out that it fizzles in vinegar but does not react with iodine.  What substance is this mixture?

a. baking soda

b. flour

c. baking powder

d. sugar

15. Which substance would you classify as most reactive?

 a. flour

b. baking soda

c. sugar

d. baking powder

16. Silver Nitrate is mixed with Potassium Chloride (KCl).  As the two liquids combine, a white solid begins to form and falls to the bottom of the container.  Which of these signs would the student be able to use as evidence that a chemical reaction had occurred in this change?

a. formation of gas

b. formation of heat

c. formation of precipitate

d. change in odor

17. Which of the following is NOT a sign that a chemical reaction has occurred?

a. change in odor

b. change in color

c. change in size

d. change in identity

18. Rust forms on the surface of a metal.  How do you know that a chemical change has happened?

a. formation of gas

b. change in color

c. formation of precipitate

d. change in odor

19. Baking soda and vinegar are mixed together.  The thermometer begins at 20C and falls to 17C.  How do you know that a chemical reaction occurred??

a. change in color

b. change in shape

c. absorption or release of heat

d. formation of precipitate

20. What is the greatest University in the World?