Evidence of Chemical Reactions

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.

• A solid is formed when heat is removed from a sample of water.

Tags

NGSS.MS-PS1-2

NGSS.MS-PS1-5

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.

Tags

NGSS.MS-PS1-2

___________________ are the elements or compounds that are formed in a chemical reaction.

• Polymers

• Bonds

• Reactants

• Products

Tags

NGSS.MS-PS1-5

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.

Tags

NGSS.MS-PS1-2

Evidence of a chemical reaction 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

Tags

NGSS.MS-PS1-2

NGSS.MS-PS1-5

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

• produces light/heat

• production of a gas

• formation of a solid

• melting

Tags

NGSS.MS-PS1-2

Coal contains carbon and other elements. Carbon dioxide forms when coal burns in the presence of oxygen. Which of these is the best evidence that a chemical reaction occurs when coal burns?

• The shape of the coal changes
• Oxygen is present
• A new substance is produced
• Coal is made up of more than one element

Tags

NGSS.MS-PS1-2

Which of these is NOT a sign that a chemical reaction occurred?

• A loss of transparency

• An unexpected color change

• A temperature change

• The formation of a solid

Tags

NGSS.MS-PS1-2

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

• water freezes to form ice

• sugar dissolves in water

• gasoline burns in a car engine

• a piece of metal expands when it is heated

Tags

NGSS.MS-PS1-2

NGSS.MS-PS1-5

In the reaction methane + oxygen turns into carbon dioxide + water, the methane and oxygen are called _______________.

• reactants
• products
• neutrals
• energizers

Tags

NGSS.MS-PS1-5