Cranberries as a natural indicator
By: Ryan Smith, Michael Such, Billy LaBud, Kyle Sardar
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)
Our indicator was a liquid so we poured it into a beaker and prepared it to be combined with out household substances.
Here we are putting our indicator into a test tube.
Our three chemicals are from left to right: sprite, white wine vinegar, and ammonia.
Colors of substances tested with natural indicator
From left to right: ammonia (dark green pH 13), white wine vinegar (pink pH 1), and sprite (light pink pH 3).
Initial color of indicator
Initial color of substances
left to right: sprite, white wine vinegar, and ammonia.
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.