Question

reflect
when you combine two or more substances called reactants, the atoms
interact, rearrange, and produce new substances called products. a
chemical reaction takes place. some chemical reactions take place
quickly, such as a burning match. others require more time, such as
chains left outside for a month exposed to weather, which causes the
iron to react with the oxygen in the air, producing a new compound
called iron hydroxide, or rust. this overall reaction can be described in
writing with the following chemical reaction equation:
4fe + 6h₂o + 3o₂ → 4fe(oh)₃
reactants products
chemical reaction - a process by which
two or more chemical substances
interact and are chemically changed,
producing different chemical substances
what do you think?
take a look at the pictures below of a smelly, rotting pumpkin; a burning campfire; and some
tarnished silverware. these images are examples of chemical reactions taking place. in each
image, how do you know a chemical reaction is taking place?
we can observe evidence of chemical reactions.
scientists confirm that a chemical reaction has occurred by determining if a new substance with
new properties was formed, sometimes using instrumentation. in most chemical reactions, there
are signs that indicate a chemical reaction has occurred. if you observe one or more of the signs,
this provides evidence that a chemical reaction may have taken place. five possible signs of a
chemical reaction are production of a gas, production of light, unexpected temperature change,
unexpected color change, and the formation of a precipitate. these signs can be helpful as long
as we remember that the only way to be certain that a chemical reaction has occurred is to identify
a new substance that was produced in the reaction. remember, not all chemical reactions will
produce one of the five signs.
evidence of chemical
reactions
color change
gas bubbles
precipitate
light formation
temperature (heat) change

Explanation:

For the smelly, rotting pumpkin: A new substance (with a bad smell, which indicates a change in properties) is formed as the pumpkin decomposes. This is a sign of a chemical reaction.
For the burning campfire: There is a production of light (and heat, which is an unexpected temperature change). These are signs of a chemical reaction (combustion).
For the tarnished silverware: There is an unexpected color change (the silverware has tarnished, which means a new substance with different color - related properties has formed on its surface). This is a sign of a chemical reaction.

Answer:

For the smelly, rotting pumpkin: A new substance (with new properties like smell) is formed. For the burning campfire: Production of light (and heat). For the tarnished silverware: Unexpected color change.