Signs of Chemical Reactions

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

Which is NOT an indication of a chemical change?

• temperature change

• formation of a precipitate

• shape change

• production of light

Tags

NGSS.MS-PS1-2

The glow stick reaction is a

• Chemical change

• Physical change

Tags

NGSS.MS-PS1-2

NGSS.MS-PS1-5

The production of carbon dioxide gas when baking soda and vinegar reacted indicated a _____________.

• Chemical change

• Physical change

Tags

NGSS.MS-PS1-2

NGSS.MS-PS1-5

Four students performed four different investigations by combining different substances. Which of the observations is most indicative of a chemical reaction?

• investigation 1

• investigation 2

• investigation 3

• investigation 4

Tags

NGSS.MS-PS1-2

NGSS.MS-PS1-5

In a container, a solid consisting of clear crystals is combined with a blue liquid and the following observations are obtained: How many of the listed observations indicate a new substance was formed?

• 1

• 2

• 3

• 4

Tags

NGSS.MS-PS1-2

NGSS.MS-PS1-4

Two clear colorless solutions were combined.
The student observed that the temperature changed from 25 •C to 23 •C when the solutions were combined and that a white substance rapidly formed and settled to the bottom of the container. What most likely happened to produce these results?

• One of the original compounds came out of solution

• The solutions reacted chemically

• Some of the water froze into ice crystals

• Rapid evaporation of water occurred, leaving a solid

Tags

NGSS.MS-PS1-2

NGSS.MS-PS1-4

The Best Friend's Club uses "invisible ink" to write notes to each other. The invisible ink is actually lemon juice that is clear when it dries on paper, but turns brown when a club member holds a burning candle under the paper. Once it is heated, it is never invisible again.
 What type of change is occurring when the paper is heated?

• chemical change

• elemental change

• physical change

• temperature change

Tags

NGSS.MS-PS1-2

NGSS.MS-PS1-4

Substances giving off a smell (____________) while being combined is also an indicator of a chemical reaction.

• light

• odor

• molecule

• precipitate

Tags

NGSS.MS-PS1-2

Which of the following is a sign of a chemical reaction?

• Change in color

• Change in shape

• Change in size

• Change in mass

Tags

NGSS.MS-PS1-2