Chemical Changes in the Lab

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
• elemental change
• physical change
• temperature change

Tags

NGSS.MS-PS1-2

NGSS.MS-PS1-4

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

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

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.

Shredding paper is an example of a 

• physical property
• physical change
• chemical change
• chemical property

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

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

Brooke mixed two liquids that produced a precipitate. She noticed the beaker became cool to the touch as the reaction progresses. What kind of reaction was this? 

• endothermic
• exothermic
• hydrothermic
• optithermic

Tags

NGSS.HS-PS1-4

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.HS-PS1-4

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

• It was hot.
• It was a gas.
• It was magnetic.
• It was a conductor.

Tags

NGSS.MS-PS1-2