Chemical Evidence

Marie 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 Marie 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.

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

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.

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.

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

• A rock breaks into smaller pieces when it is struck with a hammer.

• Rust forms on a hammer that has been left outside to long. 

• A cup of water turns pink when a few drops of red food coloring are added. 

• A solid is formed when heat is removed from a sample of water. 

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 liquids are mixed and a solid forms as a result of a reaction, the solid is called a

• participant

• percipitate

• polypeptide

• precipitate

A change in which NEW substances are formed.

• Chemical change

• Physical change

• Casual change

• Formal change

Causes a change in odor ...

• Chemical Reaction 

• Physical Reaction