Question

1. what indicators can you use to determine if a substance is acidic or alkaline (basic)? describe what happens when each is put into an acid and when each is put into a base

Explanation:

To answer this, we use common acid - base indicators. Let's take litmus paper and phenolphthalein as examples.

• Litmus paper: Litmus is a natural indicator. In acidic substances, the hydrogen ions ($H^+$) interact with the litmus molecules. For blue litmus paper, the presence of $H^+$ causes a chemical change in the litmus dye, making it turn red. In basic substances, the hydroxide ions ($OH^-$) react with litmus, and red litmus paper turns blue.
• Phenolphthalein: Phenolphthalein is an organic compound. In acidic solutions, the concentration of $H^+$ is high. The structure of phenolphthalein does not absorb visible light in the range that would make it appear colored, so it remains colorless. In basic solutions, the $OH^-$ ions react with phenolphthalein, changing its molecular structure. This new structure absorbs light in the visible spectrum, specifically in the range that makes it appear pink (or fuschia).

We can fill the table as follows:

Indicator	When put in Acid	When put in Base
Litmus Paper (Red)	No color change	Turns Blue
Phenolphthalein	Remains Colorless	Turns Pink (or Fuschia)

(We can also use other indicators like methyl orange: in acid it's red, in base it's yellow. But litmus and phenolphthalein are common and easy to describe.)

Answer:

Here is a filled table with two common indicators:

Indicator	When put in Acid	When put in Base
Phenolphthalein	Remains Colorless	Turns Pink

(Other valid indicators and their responses can also be used, e.g., Methyl Orange: in Acid - Red, in Base - Yellow)