Chemical Change/Formation of a New Substance

Bubbles and fizzing can be seen instantly when baking soda is mixed with vinegar.  The bubbles are evidence of which of the following?

• A gas is formed when baking soda and vinegar are mixed.
• Baking soda dissolves in vinegar when they are mixed.
• Vinegar turns into alcohol when it is mixed with baking soda.
• A precipitate is formed when baking soda and vinegar are mixed.

A granular substance is added to a liquid.  Which of the following would provide evidence to suggest a chemical change has taken place?

• The liquid gives off heat.
• The granules dissolve completely.
• The volume of the liquid increases.
• The granules seem to get smaller.

When two substances are mixed, they might form a new substance.  Which of the following would indicate that a new substance has been formed?

• The temperature of the mixture decreases.
• The volume of the mixture increases.
• The mass of the mixture increases.
• One of the substances dissolves.

Tags

NGSS.MS-PS1-2

NGSS.MS-PS1-4

A student mixes two clear liquids together.  After a few minutes, a white powder can be seen settling on the bottom of the test tube.  Which of the following is a conclusion that the student can draw based on these observations?  The two clear liquids-

• have combined to produce a new substance.
• were pure substances before they were mixed.
• are toxic and should be handled with extreme caution.
• have been stored too long and are no longer good.

Which of the following characteristics is shared by all chemical reactions?

• Produce a precipitate
• Show a color change
• Release heat energy
• Form new substances

All of the following are evidence of a chemical change EXCEPT-

• change in state of matter
• formation of a gas
• color change
• precipitate forms

Tags

NGSS.MS-PS1-2

Students combine several chemicals and record the observations in their science notebooks.  A list of the observed results is given here.
-Production of a gas (bubbles)
-Phase change (solid to liquid)
-A precipitate (solid) forms
-Change in shape
-Crystals dissovling
-Heat produced
How may of the observations are evidence that a new substance was formed?

• 3
• 4
• 5
• 6

Which of the following observations is the best indicator that a new substance has been formed?

• A solid has become a liquid.
• A substance has changed color.
• A solid has dissolved in a liquid.
• The volume of a substance increased.

Tags

NGSS.MS-PS1-2