Evidence of a Chemical Change

Which of these observations from a burning candle are NOT evidence of a chemical change?

• The wax is melting

• Smoke is produced

• Heat is released

Tags

NGSS.MS-PS1-2

NGSS.MS-PS1-5

A change that results in the formation of new chemical substances

• chemical change

• physical change

Tags

NGSS.MS-PS1-2

NGSS.MS-PS1-5

Which of these is a result of a chemical change?

• A mixture

• A solution

• A new substance

• Melting or freezing

Tags

NGSS.MS-PS1-2

NGSS.MS-PS1-5

A student pours a glass of soda and observes the formation of clear bubbles. Has a chemical change occurred?

• Yes, because a gas was formed from a liquid.

• No, because the gas dissolved in the soda just floats to the top of the liquid.

• No, because the soda was not heated.

• Yes, because the formation of bubbles is always an indicator of chemical change.

Tags

NGSS.MS-PS1-2

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

• Physical Change

• Elemental Change

• Temperature Change

Tags

NGSS.MS-PS1-4

A student mixes two clear liquids together. After a few minutes, a white powdery solid 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-

• were pure substances before they were mixed

• are toxic and should be handled with extreme caution

• have gone through a chemical change in which a new substance called a precipitate was produced

• have been stored too long and are no longer good

Tags

NGSS.MS-PS1-2

NGSS.MS-PS1-5

A student added white crystals to a clear liquid. The crystals dissolved in the liquid. After a few seconds, the liquid became quite warm and then turned bright red in color. Indications that a chemical change was taking place could be observed when –

• the white crystals were added to the clear liquid.

• the crystals dissolved in the liquid leaving only the liquid visible

• There are no indications of chemical change

• the temperature of the liquid increased and an unexpected color change occurred.

Tags

NGSS.MS-PS1-2

A student observes some sugar as it is heated and burns. The student concludes that a chemical reaction has occurred. Which of the following observations about the burning sugar provides evidence of a chemical reaction?

• Heat is added to the sugar crystals.

• The sugar melts and becomes a liquid.

• Gas is produced as the sugar turns black.

• No evidence of chemical reaction is present.

Tags

NGSS.MS-PS1-2

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.

Tags

NGSS.MS-PS1-2

Bethany had a beaker with a small amount of baking soda. She added a few drops of pickle juice to the baking soda and observed fizzing and bubbling. Based on her observation, which of these can Bethany determine about the new substance formed by mixing the baking soda and pickle juice?

• A chemical reaction produced a solid.

• A chemical reaction produced a gas.

• No chemical reaction took place.

• Only a physical change happened.

Tags

NGSS.MS-PS1-2