QUIZ Chapter 7 Notes- page 1

Which of the following examples shows that a chemical reaction has occurred? 

• A rock breaks into smaller pieces when it is struck with a hammer.

• Rust forms on a hammer that has been left outside to long. 

• A cup of water turns pink when a few drops of red food coloring are added. 

• Water evaporates from a solution, leaving behind solid crystals.

A student places a piece of a potato into a container of hydrogen peroxide. One observation the student makes is that bubbles form around the potato. The presence of bubbles might indicate the formation of a new substance because bubbles - 

• could show that a gas is forming
• always rise to the top of a liquid. 
• are almost always perfectly spherical.
• usually burst after a few minutes.

Which of the following is an example that includes evidence of a chemical reaction?

• A sample of zinc is placed in water and it settles to the bottom
• A solid block of ice is heated and it completely melts into a liquid. 
• Sugar that is burned gives off an odor and turns brown and then black.
• A tomato is placed into a blender and chopped up into smaller pieces.

Evidence of a chemical reactions is anything that shows - 

• a new substance has formed
• a solid dissolved in a liquid
• interaction between 2 gases
• a change in the state of matter

A precipitate is a 

• liquid that forms when two solids are reacted
• a solid that forms when two liquids are mixed
• a gas that forms when vinegar and baking soda react
• a change of color in a solution

What is the Law of Conservation of mass?

• Mass is created in a chemical reaction
• Mass is created in a physical change
• New chemicals formed from a chemical reaction have a larger overall mass than the original reactants
• Mass is never created or destroyed

The substances at the beginning of a chemical equation are called the ____

• product
• yield
• chemical symbol
• reactants

In a chemical reaction, everything to the right of the arrow is called ______________.

• Products
• Yields
• Molecules
• Reactants

Which of the following is NOT evidence that that a chemical reaction has occurred?

• produces light/heat
• production of a gas
• formation of a precipitate
• melting

Which physical state indicates that a substance has been dissolved in water?

• (aq)
• (g)
• (l)
• (s)