Evidence of Chemical Change

Four students performed four different investigations by combining different substances. Their results are shown in the table provided. In which experiment are new substances being formed?

• Experiment 1

• Experiment 2

• Experiment 3

• Experiment 4

Tags

NGSS.MS-PS1-2

NGSS.MS-PS1-5

Hydrogen peroxide breaks down to form water and oxygen gas. Which observation is evidence that a chemical reaction has occurred?

• The mass of the solution remains the same.

•  Phase changes are observed.

•  The color of the solution remains clear.

• The temperature of the solution increases. 

Tags

NGSS.MS-PS1-2

NGSS.MS-PS1-5

A clear liquid from a flask is poured into another clear liquid in a beaker. Which of the following results of this procedure would indicate a new substance was formed?

• The level of the substance in the beaker is higher after the other liquid is added.

• A yellow solid forms and then settles to the bottom of the beaker.

• Small white crystals are left behind in the flask that held the first liquid.

Tags

NGSS.MS-PS1-2

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

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

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

Tags

NGSS.MS-PS1-2

NGSS.MS-PS1-5

For an investigation a student poured a blue solution of CuSO₄ into a beaker. The student placed a shiny, silver-colored strip of zinc metal in the solution and observed the changes.
The student inferred that a chemical reaction occurred. What evidence supports this inference?

• A dark solid formed on the zinc metal.

• 
  The zinc metal remained silver-colored and shiny

• The CuSO₄ solution turned blue when the zinc metal was added.

• None of these

Tags

NGSS.MS-PS1-2

NGSS.MS-PS1-5

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

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

A scientist performed four investigations using eight different liquids. In each investigation, the scientist combined two of the liquids under a fume hood and recorded observations in the table below.In which investigation is it least likely that the liquids reacted chemically?

• 1

• 2

• 3

• 4

Tags

NGSS.MS-PS1-2

NGSS.MS-PS1-5