Question

List 3 observations that suggest a chemical reaction has taken place.

a) Change in color, change in temperature, and formation of a precipitate.
b) No change in color, no change in temperature, and no formation of a precipitate.
c) Change in pressure, change in volume, and change in density.
d) Formation of a gas, change in shape, and formation of a solution.

Answer 1

Three observations that suggest a chemical reaction has taken place are a change in color, the formation of a gas (evidenced by bubbling), and the production of a precipitate.

Step-by-step explanation:

To determine if a chemical reaction has occurred, scientists look for specific observable changes. Three strong indications that a chemical reaction has taken place include:

A change in color, indicating that a different substance has been formed.

The formation of a gas, often seen as bubbles in the mixture.

A precipitate is produced, which is a solid that forms and settles out of a liquid mixture.

These changes suggest a chemical reaction has taken place because they involve the formation of new substances with different properties than the original reactants.