pH and pH Indicators

pH

A measure of the concentration of hydrogen ions (H+) in an aqueous solution, determining if it is acidic, basic, or neutral.

Neutral pH

A pH value of 7, considered neutral, exemplified by pure water.

Acidic Solutions

Solutions with a pH less than 7; examples include lemons (pH 2), soda (pH 3), cherries (pH 4), and maple syrup (pH 5).

Basic Solutions

Solutions with a pH greater than 7; soap is an example with a pH of 9.5.

pH Scale

A scale that ranges from 0 to 14, with 0 being most acidic, 7 neutral, and 14 most basic.

pH Indicator

Substances used to determine the pH of a solution by changing color, indicating its acidity or basicity.

Methyl Orange

A pH indicator that is red in acidic solutions, changing to yellow in basic solutions, with color changes around pH 3.6.

Phenolphthalein

A pH indicator that is colorless in acidic solutions, turning light pink at pH 8.3, and deep fuchsia in stronger basic solutions.

Litmus Paper

Paper treated with litmus dyes used to indicate acidity (red paper stays red) or basicity (blue paper turns red in acids).

pH Meter

An electronic device that measures the pH of a solution, requiring calibration with a known pH before testing unknown samples.