Question

a student performs the following experiment.
step 1: she pours a colorless solution into a beaker that contains another colorless liquid. yellow particles appear in the liquid.
step 2: she lets the yellow particles settle in the beaker and then separates the colorless liquid by decantation.
what has most likely occurred in the beaker?
a chemical change in step 1 and a physical change in step 2
a physical change in step 1 and a chemical change in step 2
chemical changes in both step 1 and step 2
physical changes in both step 1 and step 2

Explanation:

• Step 1: When two colorless solutions are mixed and a new substance (yellow particles) is formed, this is a chemical change. A chemical change involves the formation of new substances with different chemical properties.
• Step 2: Decantation is a physical separation method. In this step, only the physical state (separating the liquid from the settled solid) is changed, and no new substances are formed.

Answer:

a chemical change in step 1 and a physical change in step 2