Detecting chemical reactions

Which of these is NOT a sign that a chemical change has occurred? 

• Change in shape.
• An unexpected color change
• A temperature change
• The formation of a precipitate

You know that a chemical reaction has occurred if

• there is a precipitate (new solid)

• there is a color change.

• there is a temperature change.

• All of these answers are evidence.

What indicates a chemical reaction occurred?

• Heat or Light is released
  heat or light is produced
• gas (bubbles) produced
• color change
• all of the above

A chemical change is different than a physical change because in a chemical change

• chemicals are used

• molecules do not physically touch

• a new substance is formed and in a physical no new substance is formed

• the change can be seen but in a physical change it cannot

Complete the word equations.

copper oxide + sulfuric acid →

(black)

• copper sulfate + water

  (precipitate)

• copper sulfate + water

  (blue)

• copper sulfate + water

  (white)

• copper sulfate + water

  (green)

Complete the word equations.

magnesium + hydrochloric acid →

• magnesium chloride + hydrogen

• magnesium chloride

• magnesium chloride + water

• magnesium chloride + carbon dioxide

When potassium is placed in water, hydrogen has given off. The reaction produced

• an alkali

• a precipitate

• so much heat

• a blue solution

Which is the name of the kind of solid substance formed in this figure?  

• aqueous 
• precipitate
• acid
• synthesis 

Marble Chips in Hydrochloric Acid makes a gas that turns lime water cloudy. What is the name of the gas?

• Hydrogen

• Oxygen

• Carbon Dioxide

Photosynthesis is the process plants use to make their own food from light and carbon-dioxide. This process releases Oxygen. How do you test for Oxygen?

• Turns Lime Water Cloudy

• Relights a Glowing Splint

• Burns with a Pop