Evidence of Chemical Reactions

An experiment is performed in which a crystalline substance is added to a beaker filled with room temperature water. All of the following observations would serve as evidence that a chemical change occurred, EXCEPT –

• A. the crystals dissolve.

• B. a precipitate is formed.

• C. the bottom of the beaker feels warm to the touch.

• D. bubbles begin forming within the water.

Tags

NGSS.MS-PS1-2

NGSS.MS-PS1-5

During an experiment, a student combines a solid, metallic substance with a clear liquid in a beaker. The mixtures turns hot, produces bubbles, and sparks. Based on the observations, the student can conclude that –

• A. a phase change has occurred.

• B. atoms have been rearranged to form a new substance.

• C. the products are likely harmful to human skin.

• D. the metal substance is a poor conductor of heat.

Tags

NGSS.MS-PS1-2

NGSS.MS-PS1-5

When vinegar and baking soda are combined, bubbles begin to form. Bubbles are evidence of a chemical reaction because they -

• A. are less dense than air.

• B. form at a fast rate.

• C. released a gas

• D. have no mass.

Tags

NGSS.MS-PS1-2

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

• A. After putting liquid batter into a hot pan, the batter solidifies and begins to turn brown.

• B. After turning on a blender filled with fruits, the fruit is chopped up and mixed together.

• C. After taking a tray filled with ice cubes out of the freezer, the cubes begin to melt.

• D. After adding a spoonful of sugar to a mug of hot coffee, the sugar dissolves completely.

Tags

NGSS.MS-PS1-2

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

• A. After putting liquid batter into a hot pan, the batter solidifies and begins to turn brown.

• B. After turning on a blender filled with fruits, the fruit is chopped up and mixed together.

• C. After taking a tray filled with ice cubes out of the freezer, the cubes begin to melt.

• D. After adding a spoonful of sugar to a mug of hot coffee, the sugar dissolves completely.

Tags

NGSS.MS-PS1-2

A change in which NEW substances are formed.

• Chemical change
• Physical change
• Casual change
• Formal change

Tags

NGSS.MS-PS1-2

NGSS.MS-PS1-5

Which of the following could indicate a chemical change? 

• All of the answers could indicate Chemical Change 
• a color change has occurred 
• bubbles appear 
• identifying one or more new chemical products 

Tags

NGSS.MS-PS1-2

 Which is NOT an example of chemical change?

• production of gas.
• change in color.
• change in size.
• transfer of energy.
  

Tags

NGSS.MS-PS1-2

NGSS.MS-PS1-5

A copper penny turning greenish after a few years is an example of...

• Chemical Change
• Physical Change

Tags

NGSS.MS-PS1-2

Which of the following is a PHYSICAL change?

• Getting a haircut
• Rusty metal
• sour milk
• A compound

Tags

NGSS.MS-PS1-4