H.Chem- 20%- Formative Lab: Evidence of a Chemical Change

Check box ALL of the following that would be considered an indication of a chemical change?

• melting point

• temperature change

• formation of a gas

• production of light

Which of the following best explains the difference between exothermic and endothermic reactions?

• Exothermic reactions release energy, while endothermic reactions absorb energy.

• Exothermic reactions absorb energy, while endothermic reactions release energy.

• Both exothermic and endothermic reactions release energy.

• Both exothermic and endothermic reactions absorb energy.

In the last reaction of this experiment, pieces of aluminum were placed into a solution of copper II chloride, the aluminum seemed to disappear and a brownish solid was formed. What do you think the brownish solid was, and what happened to the aluminum foil?

• The brownish solid was copper, and the aluminum chemically reacted forming aluminum chloride.

• The brownish solid was rust, and the aluminum foil remained unchanged.

• The brownish solid was aluminum oxide, and the aluminum turned into copper.

• The brownish solid was copper chloride, and the aluminum foil formed a protective layer.

Sarah made her Kool-Aid, by dissolving the powder into the liquid and stirring it. Is this a chemical reaction?

• Yes, because the ingredients are mixed and a new substance is formed.

• No, because mixing Kool-Aid is a physical change, not a chemical change.

• Yes, because the color and taste change, indicating a chemical reaction.

• No, because the process is irreversible and no new substance is formed.

Check box all of the following reactions from the lab that were considered a double replacement reaction

• Reaction #1= mixing copper (II) nitrate and sodium hydroxide

• Reaction #2= mixing sodium carbonate and calcium chloride

• Reaction # 5= calcium chloride and water

• Reaction #6= Copper (II) chloride and water

In reaction #6, aluminum pieces were placed in a copper (II) chloride solution. This was considered an ​ (a)   reaction with one of the products being ​ (b)  

• copper
• alumium
• chloride
• exothermic
• endothermic

Classify each of your reactions are endothermic or exothermic

Groups:

(a) Exothermic

,

(b) Endothermic

• Reaction #2

• Reaction #6

• Reaction #3

• Reaction #4

• Reaction #5

• Reaction # 1

Check box all the following pieces of evidence that would be valid reasons for supporting that reaction #1 was a chemical reaction.

• production of a gas

• permanent change in color

• energy change (heat, light)

• formation of a precipitate

• temperature change

Check box all the following pieces of evidence that would be valid reasons for supporting that reaction #6 was a chemical reaction.

• production of a gas

• permanent change in color

• energy change (heat, light)

• formation of a precipitate

• temperature change

Which of the following is NOT evidence of a chemical change?

• A solid precipitate forms when two solutions are mixed.

• A metal heats up when placed in hot water

• Bubbles form when vinegar is added to baking soda.

• A color change occurs in a reaction.