Living Environment Course

Chemical Indicators Notes

Note: A chemical indicator is a substance that causes a color change in the presence or absence of the chemical being tested. A positive test in any experiment means a color change has occurred.

Chemical Indicators

Results

Litmus paper

(yellow strip)

Changes to red in acids

Changes to blue in bases

Lugol’s solution (Iodine)

(brown/dark orange color)

Changes to black/dark purple when starch is detected

Benedict’s solution

(blue color)

Changes to orange when simple sugars (glucose) is detected

Bromothymol blue

(blue color)

Changes to yellow when CO2 and acids are detected

Phenolphthalein

(colorless)

Changes to colorless in acids

Changes to pink in bases

Visual Illustrations of Chemical Changes

Litmus Paper

Lugol’s Solution

Benedict’s Solution

Bromothymol Solution

Phenolphthalein Solution