Cranberries as a natural indicator

By: Ryan Smith, Michael Such, Billy LaBud, Kyle Sardar


  • Purpose:

The purpose of this lab is to determine the pH value of household substances by using cranberry juice as a natural indicator.

  • What is an indicator and why do they change colors?

An indicator is a substance that changes the color of an additional substance to show a pH value. They change color is caused by the dissociation of the H+ ion from the indicator(1). Indicators are weak acids and the dissociation of a weak acid causes a solution to change color.

  • Difference between acids and bases:

Acids: pH less than 7, sour tasting, turns blue litmus paper red, and has no effect on color of phenolphthalein indicator

Bases: pH greater than 7, bitter tasting, turns red litmus paper blue, and turns phenolphthalein indicator pink

  • Household substances we will test (with prediction):

Sprite(acid), ammonia (base), and white wine vinegar (base)




We learned from using cranberry juice as a natural indicator that when it is combined with acids a pink or light pink color is produced because an acid won't change color much when combined with an acid. When the indicator was combined with a base, a dark pink color or green color was produced.

Our indicator was better at indicating the pH for bases because there was a more recognizable color change with bases.

Some problems we encountered when using our indicator was when the indicator was combined with acidic pH values the colors were very similar. If we were to do this experiment again, we would use more chemical samples. More samples would allow us to have more pH color values to compare.

Work Cited

1.Chemical indicator. (n.d.). Retrieved June 3, 2015.