Evidence of Chemical Changes

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

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

What piece of evidence can be seen in the chemical equation below:

SiCl₄(l) + H₂O(l) → SiO₂(s) + HCl(aq)

• Change in energy (temperature, smell, or light)

• Change in color

• Formation (creation) of a gas

• Formation (creation) of a precipitate

• Formation (creation) of water

Tags

NGSS.MS-PS1-2

What are three pieces of evidence that a chemical change is occurring?

• color change

• gas production

• ice formation

• light or heat is produced

• formation of a precipitate

Tags

NGSS.MS-PS1-2

What piece of evidence is show in the written equation,

CaCO₃(s) → CaO(s) + CO₂(g)?

• formation (creation) of a precipitate

• formation (creation) of a gas

• formation (creation) of water

• change in color

• change in energy (temperature, light, smell)

Tags

NGSS.MS-PS1-2

NGSS.MS-PS1-5

what pieces of evidence can be seen in the equation below? (Pick 2)

• formation (creation) of a gas

• formation (creation) of a precipitate

• change in energy (temperature, light, smell)

• formation (creation) of water

• change in color

Tags

NGSS.MS-PS1-2

NGSS.MS-PS1-4

What pieces of evidence are written into the chemical equation below?

8 CO(g) + 17 H₂(g) → 1 C₈H₁₈(l) + 8 H₂O(g)

• formation (creation) of a gas

• formation (creation) of a precipitate

• formation (creation) of water

• change in colorf

• change in energy (temperature, light, smell)

Tags

NGSS.MS-PS1-2

What sign of a chemical reaction is observed in the written chemical equation?

• formation (creation) of a gas

• formation (creation) of a precipitate

• formation (creation) of water

• change in color

• change in energy (temperature, light, smell)

Tags

NGSS.MS-PS1-2

What piece(s) of evidence of chemical change can be observed in the written chemical equation? Select all that apply.

• formation (creation) of a gas

• formation (creation) of a precipitate

• formation (creation) of water

• change in color

• change in energy (temperature, smell, light)

Tags

NGSS.MS-PS1-2

Four students performed four different investigations by combining different substances. Their results are shown in the table to the left. In ​ ​ (a)   , a chemical reaction took place. The other experiments ​ (b)   result in a chemical reaction.

• Experiment 1
• Experiment 2
• Experiment 3
• Experiment 4
• did not
• did

Tags

NGSS.MS-PS1-2

NGSS.MS-PS1-5