Reaction
A chemical reaction is another name for a chemical change. A chemical change is the process that takes
place when one substance turns into another substance. For example, when an iron nail rusts, it
undergoes a chemical change. The iron in the nail reacts with the oxygen in the air producing a new
substance, iron oxide, which is rust.
A change in temperature is one piece of evidence that students can use to see if a chemical reaction has
taken place. Reactions can be endothermic (heat pulled in) or exothermic (heat pushed out). In an
endothermic reaction, the temperature will decrease. In an exothermic reaction, the temperature will
increase. A second piece of evidence that a chemical reaction has taken place is the production of a gas
(bubbles). A third piece of evidence is the formation of a precipitate. A precipitate is a solid substance
that forms within a liquid or even in some gases. (The solid “falls” to the bottom of the reaction.) Other
indications of a chemical reaction are the production of light or a change in color.
In the activities we will be doing, you will be examining different mixtures of chemicals. You will identify
whether a chemical reaction has taken place by looking for one of the mentioned responses – most
specifically changes in temperature or the production of a gas.
There are two possible definitions for Physical and Chemical Change:
1. A physical change is reversible; a chemical change is not. For example, the freezing of water would be
a physical change because it can be reversed, whereas the burning of wood is a chemical change - you
can not be 'unburned’.
2. A physical change is a change in which no new substance is formed; a chemical change results in the
formation of one or more new substances. Again, consider the previous examples: Freezing water into ice
just results in water molecules, which are 'stuck' together - it's still H2O. Therefore, the results of burning
wood will be ash, carbon dioxide, etc, - all new substances, which were not there when you started.
Reaction
A chemical reaction is another name for a________________________________. A chemical change is the process that
takes place when one ____________________________ turns into another substance. For example, when an iron nail
rusts, it undergoes a chemical change. The iron in the nail _________________ with the oxygen in the air producing a new
substance, iron oxide, which is rust.
A change in _________________________ is one piece of evidence that students can use to see if a chemical reaction has
taken place. Reactions can be _________________________ (heat pulled in) or _____________________________
(heat pushed out). In an endothermic reaction, the temperature will decrease. In an exothermic reaction, the temperature
will increase. A second piece of evidence that a chemical reaction has taken place is the production of a gas
(_______________________________). A third piece of evidence is the formation of
a________________________________. A precipitate is a solid substance that forms within a liquid or even in some
gases. (The solid “falls” to the bottom of the reaction.) Other indications of a chemical reaction are the production of
_________________________ or a change in ___________________________.
In the activities we will be doing, you will be examining different mixtures of chemicals. You will identify whether a chemical
reaction has taken place by looking for one of the mentioned responses – most specifically changes in temperature or the
production of a gas.
There are two possible definitions for Physical and Chemical Change:
1. A physical change is________________________________; a chemical change is not. For example, the freezing of
water would be a physical change because it can be reversed, whereas the burning of wood is a chemical change - you can
not be 'unburned’.
2. A physical change is a change in which no new substance is formed; a chemical change results in the
________________________________ of one or more new substances. Again, consider the previous examples: Freezing
water into ice just results in water molecules, which are 'stuck' together - it's still H2O. Therefore, the results of burning wood
will be ash, carbon dioxide, etc, - all new substances, which were not there when you started.
Bubbles
Chemical change
Color
Endothermic
Exothermic
Formation
Light
Precipitate
Reacts
Reversible
Substance
Temperature